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diff --git a/collectors/ebpf.plugin/README.md b/collectors/ebpf.plugin/README.md index babcd5206..c32133b1c 100644 --- a/collectors/ebpf.plugin/README.md +++ b/collectors/ebpf.plugin/README.md @@ -8,51 +8,405 @@ sidebar_label: "eBPF" # eBPF monitoring with Netdata -eBPF consists of a wide toolchain that ultimately outputs a set of bytecode that will run inside the eBPF virtual -machine (VM) which lives inside the Linux kernel. The program in particular is executed in response to a [tracepoint -or kprobe](#probes-and-tracepoints) activation. +The Netdata Agent provides many [eBPF](https://ebpf.io/what-is-ebpf/) programs to help you troubleshoot and debug how applications interact with the Linux kernel. The `ebpf.plugin` uses [tracepoints, trampoline, and2 kprobes](#data-collection) to collect a wide array of high value data about the host that would otherwise be impossible to capture. -Netdata has written many eBPF programs, which, when compiled and integrated into the Netdata Agent, are able to collect -a wide array of data about the host that would otherwise be impossible. The data eBPF programs can collect is truly unique, -which gives the Netdata Agent access to data that is high value but normally hard to capture. +> ❗ eBPF monitoring only works on Linux systems and with specific Linux kernels, including all kernels newer than `4.11.0`, and all kernels on CentOS 7.6 or later. For kernels older than `4.11.0`, improved support is in active development. -eBPF monitoring can help you troubleshoot and debug how applications interact with the Linux kernel. See -our [guide on troubleshooting apps with eBPF metrics](/docs/guides/troubleshoot/monitor-debug-applications-ebpf.md) for -configuration and troubleshooting tips. +This document provides comprehensive details about the `ebpf.plugin`. +For hands-on configuration and troubleshooting tips see our [tutorial on troubleshooting apps with eBPF metrics](/docs/guides/troubleshoot/monitor-debug-applications-ebpf.md). <figure> <img src="https://user-images.githubusercontent.com/1153921/74746434-ad6a1e00-5222-11ea-858a-a7882617ae02.png" alt="An example of VFS charts, made possible by the eBPF collector plugin" /> - <figcaption>An example of VFS charts made possible by the eBPF collector plugin.</figcaption> + <figcaption>An example of virtual file system (VFS) charts made possible by the eBPF collector plugin.</figcaption> </figure> -## Probes and Tracepoints +<a id="data-collection"> </a> -The following two features from the Linux kernel are used by Netdata to run eBPF programs: +## How Netdata collects data using probes and tracepoints -- Kprobes and return probes (kretprobe): Probes can insert virtually into any kernel instruction. When eBPF runs in - `entry` mode, it attaches only `kprobes` for internal functions monitoring calls and some arguments every time a - function is called. The user can also change configuration to use [`return`](#global) mode, and this will allow users - to monitor return from these functions and detect possible failures. -- Tracepoints are hooks to call specific functions. Tracepoints are more stable than `kprobes` and are preferred when - both options are available. +Netdata uses the following features from the Linux kernel to run eBPF programs: -In each case, wherever a normal kprobe, kretprobe, or tracepoint would have run its hook function, an eBPF program is -run instead, performing various collection logic before letting the kernel continue its normal control flow. +- Tracepoints are hooks to call specific functions. Tracepoints are more stable than `kprobes` and are preferred when + both options are available. +- Trampolines are bridges between kernel functions, and BPF programs. Netdata uses them by default whenever available. +- Kprobes and return probes (`kretprobe`): Probes can insert virtually into any kernel instruction. When eBPF runs in `entry` mode, it attaches only `kprobes` for internal functions monitoring calls and some arguments every time a function is called. The user can also change configuration to use [`return`](#global) mode, and this will allow users to monitor return from these functions and detect possible failures. -There are more methods by which eBPF programs can be triggered but which are not currently supported, such as via uprobes -which allow hooking into arbitrary user-space functions in a similar manner to kprobes. +In each case, wherever a normal kprobe, kretprobe, or tracepoint would have run its hook function, an eBPF program is run instead, performing various collection logic before letting the kernel continue its normal control flow. -## Manually enable the collector on Linux +There are more methods to trigger eBPF programs, such as uprobes, but currently are not supported. -**The eBPF collector is installed and enabled by default on most new installations of the Agent**. The eBPF collector -does not currently work with [static build installations](/packaging/installer/methods/kickstart.md#static-builds) for kernels older -than `4.11`, but improved support is in active development. +## Configuring ebpf.plugin -eBPF monitoring only works on Linux systems and with specific Linux kernels, including all kernels newer than `4.11.0`, -and all kernels on CentOS 7.6 or later. +The eBPF collector is installed and enabled by default on most new installations of the Agent. +If your Agent is v1.22 or older, you may to enable the collector yourself. -If your Agent is v1.22 or older, you may to enable the collector yourself. See the [configuration](#configuration) -section for details. +### Enable the eBPF collector + +To enable or disable the entire eBPF collector: + +1. Navigate to the [Netdata config directory](/docs/configure/nodes.md#the-netdata-config-directory). + ```bash + cd /etc/netdata + ``` + +2. Use the [`edit-config`](/docs/configure/nodes.md#use-edit-config-to-edit-configuration-files) script to edit `netdata.conf`. + + ```bash + ./edit-config netdata.conf + ``` + +3. Enable the collector by scrolling down to the `[plugins]` section. Uncomment the line `ebpf` (not + `ebpf_process`) and set it to `yes`. + + ```conf + [plugins] + ebpf = yes + ``` + +### Configure the eBPF collector + +You can configure the eBPF collector's behavior to fine-tune which metrics you receive and [optimize performance]\(#performance opimization). + +To edit the `ebpf.d.conf`: + +1. Navigate to the [Netdata config directory](/docs/configure/nodes.md#the-netdata-config-directory). + ```bash + cd /etc/netdata + ``` +2. Use the [`edit-config`](/docs/configure/nodes.md#use-edit-config-to-edit-configuration-files) script to edit [`ebpf.d.conf`](https://github.com/netdata/netdata/blob/master/collectors/ebpf.plugin/ebpf.d.conf). + + ```bash + ./edit-config ebpf.d.conf + ``` + + You can now edit the behavior of the eBPF collector. The following sections describe each configuration option in detail. + +### `[global]` configuration options + +The `[global]` section defines settings for the whole eBPF collector. + +#### eBPF load mode + +The collector uses two different eBPF programs. These programs rely on the same functions inside the kernel, but they +monitor, process, and display different kinds of information. + +By default, this plugin uses the `entry` mode. Changing this mode can create significant overhead on your operating +system, but also offer valuable information if you are developing or debugging software. The `ebpf load mode` option +accepts the following values: + +- `entry`: This is the default mode. In this mode, the eBPF collector only monitors calls for the functions described in + the sections above, and does not show charts related to errors. +- `return`: In the `return` mode, the eBPF collector monitors the same kernel functions as `entry`, but also creates new + charts for the return of these functions, such as errors. Monitoring function returns can help in debugging software, + such as failing to close file descriptors or creating zombie processes. +- `update every`: Number of seconds used for eBPF to send data for Netdata. +- `pid table size`: Defines the maximum number of PIDs stored inside the application hash table. + +#### Integration with `apps.plugin` + +The eBPF collector also creates charts for each running application through an integration with the +[`apps.plugin`](/collectors/apps.plugin/README.md). This integration helps you understand how specific applications +interact with the Linux kernel. + +If you want to _disable_ the integration with `apps.plugin` along with the above charts, change the setting `apps` to +`no`. + +```conf +[global] + apps = yes +``` + +When the integration is enabled, eBPF collector allocates memory for each process running. The total allocated memory +has direct relationship with the kernel version. When the eBPF plugin is running on kernels newer than `4.15`, it uses +per-cpu maps to speed up the update of hash tables. This also implies storing data for the same PID for each processor +it runs. + +#### Integration with `cgroups.plugin` + +The eBPF collector also creates charts for each cgroup through an integration with the +[`cgroups.plugin`](/collectors/cgroups.plugin/README.md). This integration helps you understand how a specific cgroup +interacts with the Linux kernel. + +The integration with `cgroups.plugin` is disabled by default to avoid creating overhead on your system. If you want to +_enable_ the integration with `cgroups.plugin`, change the `cgroups` setting to `yes`. + +```conf +[global] + cgroups = yes +``` + +If you do not need to monitor specific metrics for your `cgroups`, you can enable `cgroups` inside +`ebpf.d.conf`, and then disable the plugin for a specific `thread` by following the steps in the +[Configuration](#configuration) section. + +#### Integration Dashboard Elements + +When an integration is enabled, your dashboard will also show the following cgroups and apps charts using low-level +Linux metrics: + +> Note: The parenthetical accompanying each bulleted item provides the chart name. + +- mem + - Number of processes killed due out of memory. (`oomkills`) +- process + - Number of processes created with `do_fork`. (`process_create`) + - Number of threads created with `do_fork` or `clone (2)`, depending on your system's kernel + version. (`thread_create`) + - Number of times that a process called `do_exit`. (`task_exit`) + - Number of times that a process called `release_task`. (`task_close`) + - Number of times that an error happened to create thread or process. (`task_error`) +- swap + - Number of calls to `swap_readpage`. (`swap_read_call`) + - Number of calls to `swap_writepage`. (`swap_write_call`) +- network + - Number of outbound connections using TCP/IPv4. (`outbound_conn_ipv4`) + - Number of outbound connections using TCP/IPv6. (`outbound_conn_ipv6`) + - Number of bytes sent. (`total_bandwidth_sent`) + - Number of bytes received. (`total_bandwidth_recv`) + - Number of calls to `tcp_sendmsg`. (`bandwidth_tcp_send`) + - Number of calls to `tcp_cleanup_rbuf`. (`bandwidth_tcp_recv`) + - Number of calls to `tcp_retransmit_skb`. (`bandwidth_tcp_retransmit`) + - Number of calls to `udp_sendmsg`. (`bandwidth_udp_send`) + - Number of calls to `udp_recvmsg`. (`bandwidth_udp_recv`) +- file access + - Number of calls to open files. (`file_open`) + - Number of calls to open files that returned errors. (`open_error`) + - Number of files closed. (`file_closed`) + - Number of calls to close files that returned errors. (`file_error_closed`) +- vfs + - Number of calls to `vfs_unlink`. (`file_deleted`) + - Number of calls to `vfs_write`. (`vfs_write_call`) + - Number of calls to write a file that returned errors. (`vfs_write_error`) + - Number of calls to `vfs_read`. (`vfs_read_call`) + - - Number of calls to read a file that returned errors. (`vfs_read_error`) + - Number of bytes written with `vfs_write`. (`vfs_write_bytes`) + - Number of bytes read with `vfs_read`. (`vfs_read_bytes`) + - Number of calls to `vfs_fsync`. (`vfs_fsync`) + - Number of calls to sync file that returned errors. (`vfs_fsync_error`) + - Number of calls to `vfs_open`. (`vfs_open`) + - Number of calls to open file that returned errors. (`vfs_open_error`) + - Number of calls to `vfs_create`. (`vfs_create`) + - Number of calls to open file that returned errors. (`vfs_create_error`) +- page cache + - Ratio of pages accessed. (`cachestat_ratio`) + - Number of modified pages ("dirty"). (`cachestat_dirties`) + - Number of accessed pages. (`cachestat_hits`) + - Number of pages brought from disk. (`cachestat_misses`) +- directory cache + - Ratio of files available in directory cache. (`dc_hit_ratio`) + - Number of files accessed. (`dc_reference`) + - Number of files accessed that were not in cache. (`dc_not_cache`) + - Number of files not found. (`dc_not_found`) +- ipc shm + - Number of calls to `shm_get`. (`shmget_call`) + - Number of calls to `shm_at`. (`shmat_call`) + - Number of calls to `shm_dt`. (`shmdt_call`) + - Number of calls to `shm_ctl`. (`shmctl_call`) + +### `[ebpf programs]` configuration options + +The eBPF collector enables and runs the following eBPF programs by default: + +- `fd` : This eBPF program creates charts that show information about calls to open files. +- `mount`: This eBPF program creates charts that show calls to syscalls mount(2) and umount(2). +- `shm`: This eBPF program creates charts that show calls to syscalls shmget(2), shmat(2), shmdt(2) and shmctl(2). +- `sync`: Monitor calls to syscalls sync(2), fsync(2), fdatasync(2), syncfs(2), msync(2), and sync_file_range(2). +- `network viewer`: This eBPF program creates charts with information about `TCP` and `UDP` functions, including the + bandwidth consumed by each. +- `vfs`: This eBPF program creates charts that show information about VFS (Virtual File System) functions. +- `process`: This eBPF program creates charts that show information about process life. When in `return` mode, it also + creates charts showing errors when these operations are executed. +- `hardirq`: This eBPF program creates charts that show information about time spent servicing individual hardware + interrupt requests (hard IRQs). +- `softirq`: This eBPF program creates charts that show information about time spent servicing individual software + interrupt requests (soft IRQs). +- `oomkill`: This eBPF program creates a chart that shows OOM kills for all applications recognized via + the `apps.plugin` integration. Note that this program will show application charts regardless of whether apps + integration is turned on or off. + +You can also enable the following eBPF programs: + +- `cachestat`: Netdata's eBPF data collector creates charts about the memory page cache. When the integration with + [`apps.plugin`](/collectors/apps.plugin/README.md) is enabled, this collector creates charts for the whole host _and_ + for each application. +- `dcstat` : This eBPF program creates charts that show information about file access using directory cache. It appends + `kprobes` for `lookup_fast()` and `d_lookup()` to identify if files are inside directory cache, outside and files are + not found. +- `disk` : This eBPF program creates charts that show information about disk latency independent of filesystem. +- `filesystem` : This eBPF program creates charts that show information about some filesystem latency. +- `swap` : This eBPF program creates charts that show information about swap access. +- `mdflush`: This eBPF program creates charts that show information about + multi-device software flushes. + +### Configuring eBPF threads + +You can configure each thread of the eBPF data collector. This allows you to overwrite global options defined in `/etc/netdata/ebpf.d.conf` and configure specific options for each thread. + +To configure an eBPF thread: + +1. Navigate to the [Netdata config directory](/docs/configure/nodes.md#the-netdata-config-directory). + ```bash + cd /etc/netdata + ``` +2. Use the [`edit-config`](/docs/configure/nodes.md#use-edit-config-to-edit-configuration-files) script to edit a thread configuration file. The following configuration files are available: + + - `network.conf`: Configuration for the [`network` thread](#network-configuration). This config file overwrites the global options and also + lets you specify which network the eBPF collector monitors. + - `process.conf`: Configuration for the [`process` thread](#sync-configuration). + - `cachestat.conf`: Configuration for the `cachestat` thread(#filesystem-configuration). + - `dcstat.conf`: Configuration for the `dcstat` thread. + - `disk.conf`: Configuration for the `disk` thread. + - `fd.conf`: Configuration for the `file descriptor` thread. + - `filesystem.conf`: Configuration for the `filesystem` thread. + - `hardirq.conf`: Configuration for the `hardirq` thread. + - `softirq.conf`: Configuration for the `softirq` thread. + - `sync.conf`: Configuration for the `sync` thread. + - `vfs.conf`: Configuration for the `vfs` thread. + + ```bash + ./edit-config FILE.conf + ``` + +### Network configuration + +The network configuration has specific options to configure which network(s) the eBPF collector monitors. These options +are divided in the following sections: + +#### `[network connections]` + +You can configure the information shown on `outbound` and `inbound` charts with the settings in this section. + +```conf +[network connections] + maximum dimensions = 500 + resolve hostname ips = no + ports = 1-1024 !145 !domain + hostnames = !example.com + ips = !127.0.0.1/8 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 fc00::/7 +``` + +When you define a `ports` setting, Netdata will collect network metrics for that specific port. For example, if you +write `ports = 19999`, Netdata will collect only connections for itself. The `hostnames` setting accepts +[simple patterns](/libnetdata/simple_pattern/README.md). The `ports`, and `ips` settings accept negation (`!`) to deny +specific values or asterisk alone to define all values. + +In the above example, Netdata will collect metrics for all ports between 1 and 443, with the exception of 53 (domain) +and 145. + +The following options are available: + +- `ports`: Define the destination ports for Netdata to monitor. +- `hostnames`: The list of hostnames that can be resolved to an IP address. +- `ips`: The IP or range of IPs that you want to monitor. You can use IPv4 or IPv6 addresses, use dashes to define a + range of IPs, or use CIDR values. By default, only data for private IP addresses is collected, but this can + be changed with the `ips` setting. + +By default, Netdata displays up to 500 dimensions on network connection charts. If there are more possible dimensions, +they will be bundled into the `other` dimension. You can increase the number of shown dimensions by changing +the `maximum dimensions` setting. + +The dimensions for the traffic charts are created using the destination IPs of the sockets by default. This can be +changed setting `resolve hostname ips = yes` and restarting Netdata, after this Netdata will create dimensions using +the `hostnames` every time that is possible to resolve IPs to their hostnames. + +#### `[service name]` + +Netdata uses the list of services in `/etc/services` to plot network connection charts. If this file does not contain +the name for a particular service you use in your infrastructure, you will need to add it to the `[service name]` +section. + +For example, Netdata's default port (`19999`) is not listed in `/etc/services`. To associate that port with the Netdata +service in network connection charts, and thus see the name of the service instead of its port, define it: + +```conf +[service name] + 19999 = Netdata +``` + +### Sync configuration + +The sync configuration has specific options to disable monitoring for syscalls. All syscalls are monitored by default. + +```conf +[syscalls] + sync = yes + msync = yes + fsync = yes + fdatasync = yes + syncfs = yes + sync_file_range = yes +``` + +### Filesystem configuration + +The filesystem configuration has specific options to disable monitoring for filesystems; by default, all filesystems are +monitored. + +```conf +[filesystem] + btrfsdist = yes + ext4dist = yes + nfsdist = yes + xfsdist = yes + zfsdist = yes +``` + +The ebpf program `nfsdist` monitors only `nfs` mount points. + +## Troubleshooting + +If the eBPF collector does not work, you can troubleshoot it by running the `ebpf.plugin` command and investigating its +output. + +```bash +cd /usr/libexec/netdata/plugins.d/ +sudo su -s /bin/bash ./ebpf.plugin +``` + +You can also use `grep` to search the Agent's `error.log` for messages related to eBPF monitoring. + +```bash +grep -i ebpf /var/log/netdata/error.log +``` + +### Confirm kernel compatibility + +The eBPF collector only works on Linux systems and with specific Linux kernels. We support all kernels more recent than +`4.11.0`, and all kernels on CentOS 7.6 or later. + +You can run our helper script to determine whether your system can support eBPF monitoring. If it returns no output, your system is ready to compile and run the eBPF collector. + +```bash +curl -sSL https://raw.githubusercontent.com/netdata/kernel-collector/master/tools/check-kernel-config.sh | sudo bash +``` + + +If you see a warning about a missing kernel +configuration (`KPROBES KPROBES_ON_FTRACE HAVE_KPROBES BPF BPF_SYSCALL BPF_JIT`), you will need to recompile your kernel +to support this configuration. The process of recompiling Linux kernels varies based on your distribution and version. +Read the documentation for your system's distribution to learn more about the specific workflow for recompiling the +kernel, ensuring that you set all the necessary + +- [Ubuntu](https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel) +- [Debian](https://kernel-team.pages.debian.net/kernel-handbook/ch-common-tasks.html#s-common-official) +- [Fedora](https://fedoraproject.org/wiki/Building_a_custom_kernel) +- [CentOS](https://wiki.centos.org/HowTos/Custom_Kernel) +- [Arch Linux](https://wiki.archlinux.org/index.php/Kernel/Traditional_compilation) +- [Slackware](https://docs.slackware.com/howtos:slackware_admin:kernelbuilding) + +### Mount `debugfs` and `tracefs` + +The eBPF collector also requires both the `tracefs` and `debugfs` filesystems. Try mounting the `tracefs` and `debugfs` +filesystems using the commands below: + +```bash +sudo mount -t debugfs nodev /sys/kernel/debug +sudo mount -t tracefs nodev /sys/kernel/tracing +``` + +If they are already mounted, you will see an error. You can also configure your system's `/etc/fstab` configuration to +mount these filesystems on startup. More information can be found in +the [ftrace documentation](https://www.kernel.org/doc/Documentation/trace/ftrace.txt). ## Charts @@ -64,8 +418,7 @@ collected in the previous and current seconds. ### System overview -Not all charts within the System Overview menu are enabled by default, because they add around 100ns overhead for each -function call, this number is small for a human perspective, but the functions are called many times creating an impact +Not all charts within the System Overview menu are enabled by default. Charts that rely on `kprobes` are disabled by default because they add around 100ns overhead for each function call. This is a small number from a human's perspective, but the functions are called many times and create an impact on host. See the [configuration](#configuration) section for details about how to enable them. #### Processes @@ -74,12 +427,12 @@ Internally, the Linux kernel treats both processes and threads as `tasks`. To cr system calls: `fork(2)`, `vfork(2)`, and `clone(2)`. To generate this chart, the eBPF collector uses the following `tracepoints` and `kprobe`: -- `sched/sched_process_fork`: Tracepoint called after a call for `fork (2)`, `vfork (2)` and `clone (2)`. -- `sched/sched_process_exec`: Tracepoint called after a exec-family syscall. -- `kprobe/kernel_clone`: This is the main [`fork()`](https://elixir.bootlin.com/linux/v5.10/source/kernel/fork.c#L2415) - routine since kernel `5.10.0` was released. -- `kprobe/_do_fork`: Like `kernel_clone`, but this was the main function between kernels `4.2.0` and `5.9.16` -- `kprobe/do_fork`: This was the main function before kernel `4.2.0`. +- `sched/sched_process_fork`: Tracepoint called after a call for `fork (2)`, `vfork (2)` and `clone (2)`. +- `sched/sched_process_exec`: Tracepoint called after a exec-family syscall. +- `kprobe/kernel_clone`: This is the main [`fork()`](https://elixir.bootlin.com/linux/v5.10/source/kernel/fork.c#L2415) + routine since kernel `5.10.0` was released. +- `kprobe/_do_fork`: Like `kernel_clone`, but this was the main function between kernels `4.2.0` and `5.9.16` +- `kprobe/do_fork`: This was the main function before kernel `4.2.0`. #### Process Exit @@ -88,9 +441,9 @@ system that the task is finishing its work. The second step is to release the ke function `release_task`. The difference between the two dimensions can help you discover [zombie processes](https://en.wikipedia.org/wiki/Zombie_process). To get the metrics, the collector uses: -- `sched/sched_process_exit`: Tracepoint called after a task exits. -- `kprobe/release_task`: This function is called when a process exits, as the kernel still needs to remove the process - descriptor. +- `sched/sched_process_exit`: Tracepoint called after a task exits. +- `kprobe/release_task`: This function is called when a process exits, as the kernel still needs to remove the process + descriptor. #### Task error @@ -100,7 +453,7 @@ process and thread creation only. #### Swap Inside the swap submenu the eBPF plugin creates the chart `swapcalls`; this chart is displaying when processes are -calling functions [`swap_readpage` and `swap_writepage`](https://hzliu123.github.io/linux-kernel/Page%20Cache%20in%20Linux%202.6.pdf ), +calling functions [`swap_readpage` and `swap_writepage`](https://hzliu123.github.io/linux-kernel/Page%20Cache%20in%20Linux%202.6.pdf), which are functions responsible for doing IO in swap memory. To collect the exact moment that an access to swap happens, the collector attaches `kprobes` for cited functions. @@ -108,91 +461,108 @@ the collector attaches `kprobes` for cited functions. The following `tracepoints` are used to measure time usage for soft IRQs: -- [`irq/softirq_entry`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_softirq_entry): Called - before softirq handler -- [`irq/softirq_exit`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_softirq_exit): Called when - softirq handler returns. +- [`irq/softirq_entry`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_softirq_entry): Called + before softirq handler +- [`irq/softirq_exit`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_softirq_exit): Called when + softirq handler returns. #### Hard IRQ The following tracepoints are used to measure the latency of servicing a hardware interrupt request (hard IRQ). -- [`irq/irq_handler_entry`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_irq_handler_entry): - Called immediately before the IRQ action handler. -- [`irq/irq_handler_exit`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_irq_handler_exit): - Called immediately after the IRQ action handler returns. -- `irq_vectors`: These are traces from `irq_handler_entry` and - `irq_handler_exit` when an IRQ is handled. The following elements from vector - are triggered: - - `irq_vectors/local_timer_entry` - - `irq_vectors/local_timer_exit` - - `irq_vectors/reschedule_entry` - - `irq_vectors/reschedule_exit` - - `irq_vectors/call_function_entry` - - `irq_vectors/call_function_exit` - - `irq_vectors/call_function_single_entry` - - `irq_vectors/call_function_single_xit` - - `irq_vectors/irq_work_entry` - - `irq_vectors/irq_work_exit` - - `irq_vectors/error_apic_entry` - - `irq_vectors/error_apic_exit` - - `irq_vectors/thermal_apic_entry` - - `irq_vectors/thermal_apic_exit` - - `irq_vectors/threshold_apic_entry` - - `irq_vectors/threshold_apic_exit` - - `irq_vectors/deferred_error_entry` - - `irq_vectors/deferred_error_exit` - - `irq_vectors/spurious_apic_entry` - - `irq_vectors/spurious_apic_exit` - - `irq_vectors/x86_platform_ipi_entry` - - `irq_vectors/x86_platform_ipi_exit` +- [`irq/irq_handler_entry`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_irq_handler_entry): + Called immediately before the IRQ action handler. +- [`irq/irq_handler_exit`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_irq_handler_exit): + Called immediately after the IRQ action handler returns. +- `irq_vectors`: These are traces from `irq_handler_entry` and + `irq_handler_exit` when an IRQ is handled. The following elements from vector + are triggered: + - `irq_vectors/local_timer_entry` + - `irq_vectors/local_timer_exit` + - `irq_vectors/reschedule_entry` + - `irq_vectors/reschedule_exit` + - `irq_vectors/call_function_entry` + - `irq_vectors/call_function_exit` + - `irq_vectors/call_function_single_entry` + - `irq_vectors/call_function_single_xit` + - `irq_vectors/irq_work_entry` + - `irq_vectors/irq_work_exit` + - `irq_vectors/error_apic_entry` + - `irq_vectors/error_apic_exit` + - `irq_vectors/thermal_apic_entry` + - `irq_vectors/thermal_apic_exit` + - `irq_vectors/threshold_apic_entry` + - `irq_vectors/threshold_apic_exit` + - `irq_vectors/deferred_error_entry` + - `irq_vectors/deferred_error_exit` + - `irq_vectors/spurious_apic_entry` + - `irq_vectors/spurious_apic_exit` + - `irq_vectors/x86_platform_ipi_entry` + - `irq_vectors/x86_platform_ipi_exit` #### IPC shared memory -To monitor shared memory system call counts, the following `kprobes` are used: +To monitor shared memory system call counts, Netdata attaches tracing in the following functions: -- `shmget`: Runs when [`shmget`](https://man7.org/linux/man-pages/man2/shmget.2.html) is called. -- `shmat`: Runs when [`shmat`](https://man7.org/linux/man-pages/man2/shmat.2.html) is called. -- `shmdt`: Runs when [`shmdt`](https://man7.org/linux/man-pages/man2/shmat.2.html) is called. -- `shmctl`: Runs when [`shmctl`](https://man7.org/linux/man-pages/man2/shmctl.2.html) is called. +- `shmget`: Runs when [`shmget`](https://man7.org/linux/man-pages/man2/shmget.2.html) is called. +- `shmat`: Runs when [`shmat`](https://man7.org/linux/man-pages/man2/shmat.2.html) is called. +- `shmdt`: Runs when [`shmdt`](https://man7.org/linux/man-pages/man2/shmat.2.html) is called. +- `shmctl`: Runs when [`shmctl`](https://man7.org/linux/man-pages/man2/shmctl.2.html) is called. ### Memory In the memory submenu the eBPF plugin creates two submenus **page cache** and **synchronization** with the following organization: -* Page Cache - * Page cache ratio - * Dirty pages - * Page cache hits - * Page cache misses -* Synchronization - * File sync - * Memory map sync - * File system sync - * File range sync +- Page Cache + - Page cache ratio + - Dirty pages + - Page cache hits + - Page cache misses +- Synchronization + - File sync + - Memory map sync + - File system sync + - File range sync -#### Page cache ratio +#### Page cache hits -The chart `cachestat_ratio` shows how processes are accessing page cache. In a normal scenario, we expect values around -100%, which means that the majority of the work on the machine is processed in memory. To calculate the ratio, Netdata -attaches `kprobes` for kernel functions: +When the processor needs to read or write a location in main memory, it checks for a corresponding entry in the page cache. + If the entry is there, a page cache hit has occurred and the read is from the cache. -- `add_to_page_cache_lru`: Page addition. -- `mark_page_accessed`: Access to cache. -- `account_page_dirtied`: Dirty (modified) pages. -- `mark_buffer_dirty`: Writes to page cache. +A page cache hit is when the page cache is successfully accessed with a read operation. We do not count pages that were +added relatively recently. #### Dirty pages +A "dirty page" is a page in the page cache that was modified after being created. Since non-dirty pages in the page cache + have identical copies in secondary storage (e.g. hard disk drive or solid-state drive), discarding and reusing their space + is much quicker than paging out application memory, and is often preferred over flushing the dirty pages into secondary storage + and reusing their space. + On `cachestat_dirties` Netdata demonstrates the number of pages that were modified. This chart shows the number of calls to the function `mark_buffer_dirty`. -#### Page cache hits +#### Page cache ratio -A page cache hit is when the page cache is successfully accessed with a read operation. We do not count pages that were -added relatively recently. +When the processor needs to read or write in a specific memory address, it checks for a corresponding entry in the page cache. +If the processor hits a page cache (`page cache hit`), it reads the entry from the cache. If there is no entry (`page cache miss`), + the kernel allocates a new entry and copies data from the disk. Netdata calculates the percentage of accessed files that are cached on + memory. The ratio is calculated counting the accessed cached pages + (without counting [dirty pages](#dirty-pages) and pages added because of read misses) divided by total access without dirty pages. + +> \_\_**\_\_\_\_**<ins>Number of accessed cached pages</ins>\***\*\_\_\*\***<br/> +> Number of total accessed pages - dirty pages - missed pages + +The chart `cachestat_ratio` shows how processes are accessing page cache. In a normal scenario, we expect values around +100%, which means that the majority of the work on the machine is processed in memory. To calculate the ratio, Netdata +attaches `kprobes` for kernel functions: + +- `add_to_page_cache_lru`: Page addition. +- `mark_page_accessed`: Access to cache. +- `account_page_dirtied`: Dirty (modified) pages. +- `mark_buffer_dirty`: Writes to page cache. #### Page cache misses @@ -213,7 +583,7 @@ changes to a file that was mapped into memory using [`mmap(2)`](https://man7.org #### File system sync -This chart monitors calls demonstrating commits from filesystem caches to disk. Netdata attaches `kprobes` for +This chart monitors calls demonstrating commits from filesystem caches to disk. Netdata attaches `tracing` for [`sync(2)`](https://man7.org/linux/man-pages/man2/sync.2.html), and [`syncfs(2)`](https://man7.org/linux/man-pages/man2/sync.2.html). #### File range sync @@ -240,23 +610,35 @@ By default, MD flush is disabled. To enable it, configure your To collect data related to Linux multi-device (MD) flushing, the following kprobe is used: -- `kprobe/md_flush_request`: called whenever a request for flushing multi-device data is made. +- `kprobe/md_flush_request`: called whenever a request for flushing multi-device data is made. ### Disk -The eBPF plugin also shows a chart in the Disk section when the `disk` thread is enabled. This will create the -chart `disk_latency_io` for each disk on the host. The following tracepoints are used: +The eBPF plugin also shows a chart in the Disk section when the `disk` thread is enabled. + +#### Disk Latency + +This will create the chart `disk_latency_io` for each disk on the host. The following tracepoints are used: -- [`block/block_rq_issue`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_block_rq_issue): - IO request operation to a device drive. -- [`block/block_rq_complete`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_block_rq_complete): - IO operation completed by device. +- [`block/block_rq_issue`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_block_rq_issue): + IO request operation to a device drive. +- [`block/block_rq_complete`](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html#c.trace_block_rq_complete): + IO operation completed by device. + +Disk Latency is the single most important metric to focus on when it comes to storage performance, under most circumstances. +For hard drives, an average latency somewhere between 10 to 20 ms can be considered acceptable. For SSD (Solid State Drives), +in most cases, workloads experience less than 1 ms latency numbers, but workloads should never reach higher than 3 ms. +The dimensions refer to time intervals. ### Filesystem -This group has charts demonstrating how applications interact with the Linux -kernel to open and close file descriptors. It also brings latency charts for -several different filesystems. +This group has charts demonstrating how applications interact with the Linux kernel to open and close file descriptors. +It also brings latency charts for several different filesystems. + +#### Latency Algorithm + +We calculate the difference between the calling and return times, spanning disk I/O, file system operations (lock, I/O), +run queue latency and all events related to the monitored action. #### ext4 @@ -265,10 +647,10 @@ To measure the latency of executing some actions in an collector needs to attach `kprobes` and `kretprobes` for each of the following functions: -- `ext4_file_read_iter`: Function used to measure read latency. -- `ext4_file_write_iter`: Function used to measure write latency. -- `ext4_file_open`: Function used to measure open latency. -- `ext4_sync_file`: Function used to measure sync latency. +- `ext4_file_read_iter`: Function used to measure read latency. +- `ext4_file_write_iter`: Function used to measure write latency. +- `ext4_file_open`: Function used to measure open latency. +- `ext4_sync_file`: Function used to measure sync latency. #### ZFS @@ -276,10 +658,10 @@ To measure the latency of executing some actions in a zfs filesystem, the collector needs to attach `kprobes` and `kretprobes` for each of the following functions: -- `zpl_iter_read`: Function used to measure read latency. -- `zpl_iter_write`: Function used to measure write latency. -- `zpl_open`: Function used to measure open latency. -- `zpl_fsync`: Function used to measure sync latency. +- `zpl_iter_read`: Function used to measure read latency. +- `zpl_iter_write`: Function used to measure write latency. +- `zpl_open`: Function used to measure open latency. +- `zpl_fsync`: Function used to measure sync latency. #### XFS @@ -288,10 +670,10 @@ To measure the latency of executing some actions in an collector needs to attach `kprobes` and `kretprobes` for each of the following functions: -- `xfs_file_read_iter`: Function used to measure read latency. -- `xfs_file_write_iter`: Function used to measure write latency. -- `xfs_file_open`: Function used to measure open latency. -- `xfs_file_fsync`: Function used to measure sync latency. +- `xfs_file_read_iter`: Function used to measure read latency. +- `xfs_file_write_iter`: Function used to measure write latency. +- `xfs_file_open`: Function used to measure open latency. +- `xfs_file_fsync`: Function used to measure sync latency. #### NFS @@ -300,11 +682,11 @@ To measure the latency of executing some actions in an collector needs to attach `kprobes` and `kretprobes` for each of the following functions: -- `nfs_file_read`: Function used to measure read latency. -- `nfs_file_write`: Function used to measure write latency. -- `nfs_file_open`: Functions used to measure open latency. -- `nfs4_file_open`: Functions used to measure open latency for NFS v4. -- `nfs_getattr`: Function used to measure sync latency. +- `nfs_file_read`: Function used to measure read latency. +- `nfs_file_write`: Function used to measure write latency. +- `nfs_file_open`: Functions used to measure open latency. +- `nfs4_file_open`: Functions used to measure open latency for NFS v4. +- `nfs_getattr`: Function used to measure sync latency. #### btrfs @@ -312,26 +694,26 @@ To measure the latency of executing some actions in a [btrfs](https://elixir.boo filesystem, the collector needs to attach `kprobes` and `kretprobes` for each of the following functions: > Note: We are listing two functions used to measure `read` latency, but we use either `btrfs_file_read_iter` or -`generic_file_read_iter`, depending on kernel version. +> `generic_file_read_iter`, depending on kernel version. -- `btrfs_file_read_iter`: Function used to measure read latency since kernel `5.10.0`. -- `generic_file_read_iter`: Like `btrfs_file_read_iter`, but this function was used before kernel `5.10.0`. -- `btrfs_file_write_iter`: Function used to write data. -- `btrfs_file_open`: Function used to open files. -- `btrfs_sync_file`: Function used to synchronize data to filesystem. +- `btrfs_file_read_iter`: Function used to measure read latency since kernel `5.10.0`. +- `generic_file_read_iter`: Like `btrfs_file_read_iter`, but this function was used before kernel `5.10.0`. +- `btrfs_file_write_iter`: Function used to write data. +- `btrfs_file_open`: Function used to open files. +- `btrfs_sync_file`: Function used to synchronize data to filesystem. #### File descriptor To give metrics related to `open` and `close` events, instead of attaching kprobes for each syscall used to do these events, the collector attaches `kprobes` for the common function used for syscalls: -- [`do_sys_open`](https://0xax.gitbooks.io/linux-insides/content/SysCall/linux-syscall-5.html ): Internal function used to - open files. -- [`do_sys_openat2`](https://elixir.bootlin.com/linux/v5.6/source/fs/open.c#L1162): - Function called from `do_sys_open` since version `5.6.0`. -- [`close_fd`](https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2271761.html): Function used to close file - descriptor since kernel `5.11.0`. -- `__close_fd`: Function used to close files before version `5.11.0`. +- [`do_sys_open`](https://0xax.gitbooks.io/linux-insides/content/SysCall/linux-syscall-5.html): Internal function used to + open files. +- [`do_sys_openat2`](https://elixir.bootlin.com/linux/v5.6/source/fs/open.c#L1162): + Function called from `do_sys_open` since version `5.6.0`. +- [`close_fd`](https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2271761.html): Function used to close file + descriptor since kernel `5.11.0`. +- `__close_fd`: Function used to close files before version `5.11.0`. #### File error @@ -351,22 +733,22 @@ To measure the latency and total quantity of executing some VFS-level functions, ebpf.plugin needs to attach kprobes and kretprobes for each of the following functions: -- `vfs_write`: Function used monitoring the number of successful & failed - filesystem write calls, as well as the total number of written bytes. -- `vfs_writev`: Same function as `vfs_write` but for vector writes (i.e. a - single write operation using a group of buffers rather than 1). -- `vfs_read`: Function used for monitoring the number of successful & failed - filesystem read calls, as well as the total number of read bytes. -- `vfs_readv` Same function as `vfs_read` but for vector reads (i.e. a single - read operation using a group of buffers rather than 1). -- `vfs_unlink`: Function used for monitoring the number of successful & failed - filesystem unlink calls. -- `vfs_fsync`: Function used for monitoring the number of successful & failed - filesystem fsync calls. -- `vfs_open`: Function used for monitoring the number of successful & failed - filesystem open calls. -- `vfs_create`: Function used for monitoring the number of successful & failed - filesystem create calls. +- `vfs_write`: Function used monitoring the number of successful & failed + filesystem write calls, as well as the total number of written bytes. +- `vfs_writev`: Same function as `vfs_write` but for vector writes (i.e. a + single write operation using a group of buffers rather than 1). +- `vfs_read`: Function used for monitoring the number of successful & failed + filesystem read calls, as well as the total number of read bytes. +- `vfs_readv` Same function as `vfs_read` but for vector reads (i.e. a single + read operation using a group of buffers rather than 1). +- `vfs_unlink`: Function used for monitoring the number of successful & failed + filesystem unlink calls. +- `vfs_fsync`: Function used for monitoring the number of successful & failed + filesystem fsync calls. +- `vfs_open`: Function used for monitoring the number of successful & failed + filesystem open calls. +- `vfs_create`: Function used for monitoring the number of successful & failed + filesystem create calls. ##### VFS Deleted objects @@ -406,30 +788,49 @@ Metrics for directory cache are collected using kprobe for `lookup_fast`, becaus times this function is accessed. On the other hand, for `d_lookup` we are not only interested in the number of times it is accessed, but also in possible errors, so we need to attach a `kretprobe`. For this reason, the following is used: -- [`lookup_fast`](https://lwn.net/Articles/649115/): Called to look at data inside the directory cache. -- [`d_lookup`](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/dcache.c?id=052b398a43a7de8c68c13e7fa05d6b3d16ce6801#n2223): - Called when the desired file is not inside the directory cache. +- [`lookup_fast`](https://lwn.net/Articles/649115/): Called to look at data inside the directory cache. +- [`d_lookup`](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/dcache.c?id=052b398a43a7de8c68c13e7fa05d6b3d16ce6801#n2223): + Called when the desired file is not inside the directory cache. + +##### Directory Cache Interpretation + +When directory cache is showing 100% that means that every accessed file was present in the directory cache. +If files are not present in the directory cache, they are either not present in the file system or the files were not +accessed before. ### Mount Points -The following `kprobes` are used to collect `mount` & `unmount` call counts: +The following `tracing` are used to collect `mount` & `unmount` call counts: -- [`mount`](https://man7.org/linux/man-pages/man2/mount.2.html): mount filesystem on host. -- [`umount`](https://man7.org/linux/man-pages/man2/umount.2.html): umount filesystem on host. +- [`mount`](https://man7.org/linux/man-pages/man2/mount.2.html): mount filesystem on host. +- [`umount`](https://man7.org/linux/man-pages/man2/umount.2.html): umount filesystem on host. ### Networking Stack -Netdata monitors socket bandwidth attaching `kprobes` for internal functions. +Netdata monitors socket bandwidth attaching `tracing` for internal functions. + +#### TCP outbound connections + +This chart demonstrates calls to `tcp_v4_connection` and `tcp_v6_connection` that start connections for IPV4 and IPV6, respectively. -#### TCP functions +#### TCP inbound connections + +This chart demonstrates TCP and UDP connections that the host receives. +To collect this information, netdata attaches a tracing to `inet_csk_accept`. + +#### TCP bandwidth functions This chart demonstrates calls to functions `tcp_sendmsg`, `tcp_cleanup_rbuf`, and `tcp_close`; these functions are used to send & receive data and to close connections when `TCP` protocol is used. #### TCP bandwidth -Like the previous chart, this one also monitors `tcp_sendmsg` and `tcp_cleanup_rbuf`, but instead of showing the number -of calls, it demonstrates the number of bytes sent and received. +This chart demonstrates calls to functions: + +- `tcp_sendmsg`: Function responsible to send data for a specified destination. +- `tcp_cleanup_rbuf`: We use this function instead of `tcp_recvmsg`, because the last one misses `tcp_read_sock` traffic + and we would also need to add more `tracing` to get the socket and package size. +- `tcp_close`: Function responsible to close connection. #### TCP retransmit @@ -452,359 +853,11 @@ calls, it monitors the number of bytes sent and received. These are tracepoints related to [OOM](https://en.wikipedia.org/wiki/Out_of_memory) killing processes. -- `oom/mark_victim`: Monitors when an oomkill event happens. - -## Configuration - -Enable or disable the entire eBPF collector by editing `netdata.conf`. - -```bash -cd /etc/netdata/ # Replace with your Netdata configuration directory, if not /etc/netdata/ -./edit-config netdata.conf -``` - -To enable the collector, scroll down to the `[plugins]` section ensure the relevant line references `ebpf` (not -`ebpf_process`), is uncommented, and is set to `yes`. - -```conf -[plugins] - ebpf = yes -``` - -You can also configure the eBPF collector's behavior by editing `ebpf.d.conf`. - -```bash -cd /etc/netdata/ # Replace with your Netdata configuration directory, if not /etc/netdata/ -./edit-config ebpf.d.conf -``` - -### `[global]` - -The `[global]` section defines settings for the whole eBPF collector. - -#### eBPF load mode - -The collector has two different eBPF programs. These programs monitor the same functions inside the kernel, but they -monitor, process, and display different kinds of information. - -By default, this plugin uses the `entry` mode. Changing this mode can create significant overhead on your operating -system, but also offer valuable information if you are developing or debugging software. The `ebpf load mode` option -accepts the following values: - -- `entry`: This is the default mode. In this mode, the eBPF collector only monitors calls for the functions described in - the sections above, and does not show charts related to errors. -- `return`: In the `return` mode, the eBPF collector monitors the same kernel functions as `entry`, but also creates new - charts for the return of these functions, such as errors. Monitoring function returns can help in debugging software, - such as failing to close file descriptors or creating zombie processes. -- `update every`: Number of seconds used for eBPF to send data for Netdata. -- `pid table size`: Defines the maximum number of PIDs stored inside the application hash table. - -#### Integration with `apps.plugin` - -The eBPF collector also creates charts for each running application through an integration with the -[`apps.plugin`](/collectors/apps.plugin/README.md). This integration helps you understand how specific applications -interact with the Linux kernel. - -If you want to _disable_ the integration with `apps.plugin` along with the above charts, change the setting `apps` to -`no`. - -```conf -[global] - apps = yes -``` - -When the integration is enabled, eBPF collector allocates memory for each process running. The total allocated memory -has direct relationship with the kernel version. When the eBPF plugin is running on kernels newer than `4.15`, it uses -per-cpu maps to speed up the update of hash tables. This also implies storing data for the same PID for each processor -it runs. - -#### Integration with `cgroups.plugin` - -The eBPF collector also creates charts for each cgroup through an integration with the -[`cgroups.plugin`](/collectors/cgroups.plugin/README.md). This integration helps you understand how a specific cgroup -interacts with the Linux kernel. - -The integration with `cgroups.plugin` is disabled by default to avoid creating overhead on your system. If you want to -_enable_ the integration with `cgroups.plugin`, change the `cgroups` setting to `yes`. - -```conf -[global] - cgroups = yes -``` - -If you do not need to monitor specific metrics for your `cgroups`, you can enable `cgroups` inside -`ebpf.d.conf`, and then disable the plugin for a specific `thread` by following the steps in the -[Configuration](#configuration) section. - -#### Integration Dashboard Elements - -When an integration is enabled, your dashboard will also show the following cgroups and apps charts using low-level -Linux metrics: - -> Note: The parenthetical accompanying each bulleted item provides the chart name. - -- mem - - Number of processes killed due out of memory. (`oomkills`) -- process - - Number of processes created with `do_fork`. (`process_create`) - - Number of threads created with `do_fork` or `clone (2)`, depending on your system's kernel - version. (`thread_create`) - - Number of times that a process called `do_exit`. (`task_exit`) - - Number of times that a process called `release_task`. (`task_close`) - - Number of times that an error happened to create thread or process. (`task_error`) -- swap - - Number of calls to `swap_readpage`. (`swap_read_call`) - - Number of calls to `swap_writepage`. (`swap_write_call`) -- network - - Number of bytes sent. (`total_bandwidth_sent`) - - Number of bytes received. (`total_bandwidth_recv`) - - Number of calls to `tcp_sendmsg`. (`bandwidth_tcp_send`) - - Number of calls to `tcp_cleanup_rbuf`. (`bandwidth_tcp_recv`) - - Number of calls to `tcp_retransmit_skb`. (`bandwidth_tcp_retransmit`) - - Number of calls to `udp_sendmsg`. (`bandwidth_udp_send`) - - Number of calls to `udp_recvmsg`. (`bandwidth_udp_recv`) -- file access - - Number of calls to open files. (`file_open`) - - Number of calls to open files that returned errors. (`open_error`) - - Number of files closed. (`file_closed`) - - Number of calls to close files that returned errors. (`file_error_closed`) -- vfs - - Number of calls to `vfs_unlink`. (`file_deleted`) - - Number of calls to `vfs_write`. (`vfs_write_call`) - - Number of calls to write a file that returned errors. (`vfs_write_error`) - - Number of calls to `vfs_read`. (`vfs_read_call`) - - Number of bytes written with `vfs_write`. (`vfs_write_bytes`) - - Number of bytes read with `vfs_read`. (`vfs_read_bytes`) - - Number of calls to read a file that returned errors. (`vfs_read_error`) - - Number of calls to `vfs_fsync`. (`vfs_fsync`) - - Number of calls to sync file that returned errors. (`vfs_fsync_error`) - - Number of calls to `vfs_open`. (`vfs_open`) - - Number of calls to open file that returned errors. (`vfs_open_error`) - - Number of calls to `vfs_create`. (`vfs_create`) - - Number of calls to open file that returned errors. (`vfs_create_error`) -- page cache - - Ratio of pages accessed. (`cachestat_ratio`) - - Number of modified pages ("dirty"). (`cachestat_dirties`) - - Number of accessed pages. (`cachestat_hits`) - - Number of pages brought from disk. (`cachestat_misses`) -- directory cache - - Ratio of files available in directory cache. (`dc_hit_ratio`) - - Number of files accessed. (`dc_reference`) - - Number of files accessed that were not in cache. (`dc_not_cache`) - - Number of files not found. (`dc_not_found`) -- ipc shm - - Number of calls to `shm_get`. (`shmget_call`) - - Number of calls to `shm_at`. (`shmat_call`) - - Number of calls to `shm_dt`. (`shmdt_call`) - - Number of calls to `shm_ctl`. (`shmctl_call`) - -### `[ebpf programs]` - -The eBPF collector enables and runs the following eBPF programs by default: - -- `fd` : This eBPF program creates charts that show information about calls to open files. -- `mount`: This eBPF program creates charts that show calls to syscalls mount(2) and umount(2). -- `shm`: This eBPF program creates charts that show calls to syscalls shmget(2), shmat(2), shmdt(2) and shmctl(2). -- `sync`: Monitor calls to syscalls sync(2), fsync(2), fdatasync(2), syncfs(2), msync(2), and sync_file_range(2). -- `network viewer`: This eBPF program creates charts with information about `TCP` and `UDP` functions, including the - bandwidth consumed by each. -- `vfs`: This eBPF program creates charts that show information about VFS (Virtual File System) functions. -- `process`: This eBPF program creates charts that show information about process life. When in `return` mode, it also - creates charts showing errors when these operations are executed. -- `hardirq`: This eBPF program creates charts that show information about time spent servicing individual hardware - interrupt requests (hard IRQs). -- `softirq`: This eBPF program creates charts that show information about time spent servicing individual software - interrupt requests (soft IRQs). -- `oomkill`: This eBPF program creates a chart that shows OOM kills for all applications recognized via - the `apps.plugin` integration. Note that this program will show application charts regardless of whether apps - integration is turned on or off. - -You can also enable the following eBPF programs: - -- `cachestat`: Netdata's eBPF data collector creates charts about the memory page cache. When the integration with - [`apps.plugin`](/collectors/apps.plugin/README.md) is enabled, this collector creates charts for the whole host _and_ - for each application. -- `dcstat` : This eBPF program creates charts that show information about file access using directory cache. It appends - `kprobes` for `lookup_fast()` and `d_lookup()` to identify if files are inside directory cache, outside and files are - not found. -- `disk` : This eBPF program creates charts that show information about disk latency independent of filesystem. -- `filesystem` : This eBPF program creates charts that show information about some filesystem latency. -- `swap` : This eBPF program creates charts that show information about swap access. -- `mdflush`: This eBPF program creates charts that show information about - multi-device software flushes. - -## Thread configuration - -You can configure each thread of the eBPF data collector by editing either the `cachestat.conf`, `process.conf`, -or `network.conf` files. Use [`edit-config`](/docs/configure/nodes.md) from your Netdata config directory: - -```bash -cd /etc/netdata/ # Replace with your Netdata configuration directory, if not /etc/netdata/ -./edit-config ebpf.d/process.conf -``` - -### Configuration files - -The following configuration files are available: - -- `cachestat.conf`: Configuration for the `cachestat` thread. -- `dcstat.conf`: Configuration for the `dcstat` thread. -- `disk.conf`: Configuration for the `disk` thread. -- `fd.conf`: Configuration for the `file descriptor` thread. -- `filesystem.conf`: Configuration for the `filesystem` thread. -- `hardirq.conf`: Configuration for the `hardirq` thread. -- `process.conf`: Configuration for the `process` thread. -- `network.conf`: Configuration for the `network viewer` thread. This config file overwrites the global options and also - lets you specify which network the eBPF collector monitors. -- `softirq.conf`: Configuration for the `softirq` thread. -- `sync.conf`: Configuration for the `sync` thread. -- `vfs.conf`: Configuration for the `vfs` thread. - -### Network configuration - -The network configuration has specific options to configure which network(s) the eBPF collector monitors. These options -are divided in the following sections: - -#### `[network connections]` - -You can configure the information shown on `outbound` and `inbound` charts with the settings in this section. - -```conf -[network connections] - maximum dimensions = 500 - resolve hostname ips = no - ports = 1-1024 !145 !domain - hostnames = !example.com - ips = !127.0.0.1/8 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 fc00::/7 -``` - -When you define a `ports` setting, Netdata will collect network metrics for that specific port. For example, if you -write `ports = 19999`, Netdata will collect only connections for itself. The `hostnames` setting accepts -[simple patterns](/libnetdata/simple_pattern/README.md). The `ports`, and `ips` settings accept negation (`!`) to deny -specific values or asterisk alone to define all values. - -In the above example, Netdata will collect metrics for all ports between 1 and 443, with the exception of 53 (domain) -and 145. - -The following options are available: - -- `ports`: Define the destination ports for Netdata to monitor. -- `hostnames`: The list of hostnames that can be resolved to an IP address. -- `ips`: The IP or range of IPs that you want to monitor. You can use IPv4 or IPv6 addresses, use dashes to define a - range of IPs, or use CIDR values. The default behavior is to only collect data for private IP addresses, but this can - be changed with the `ips` setting. - -By default, Netdata displays up to 500 dimensions on network connection charts. If there are more possible dimensions, -they will be bundled into the `other` dimension. You can increase the number of shown dimensions by changing -the `maximum dimensions` setting. - -The dimensions for the traffic charts are created using the destination IPs of the sockets by default. This can be -changed setting `resolve hostname ips = yes` and restarting Netdata, after this Netdata will create dimensions using -the `hostnames` every time that is possible to resolve IPs to their hostnames. - -#### `[service name]` - -Netdata uses the list of services in `/etc/services` to plot network connection charts. If this file does not contain -the name for a particular service you use in your infrastructure, you will need to add it to the `[service name]` -section. - -For example, Netdata's default port (`19999`) is not listed in `/etc/services`. To associate that port with the Netdata -service in network connection charts, and thus see the name of the service instead of its port, define it: - -```conf -[service name] - 19999 = Netdata -``` - -### Sync configuration - -The sync configuration has specific options to disable monitoring for syscalls, as default option all syscalls are -monitored. - -```conf -[syscalls] - sync = yes - msync = yes - fsync = yes - fdatasync = yes - syncfs = yes - sync_file_range = yes -``` - -### Filesystem configuration - -The filesystem configuration has specific options to disable monitoring for filesystems, by default all filesystems are -monitored. - -```conf -[filesystem] - btrfsdist = yes - ext4dist = yes - nfsdist = yes - xfsdist = yes - zfsdist = yes -``` - -The ebpf program `nfsdist` monitors only `nfs` mount points. - -## Troubleshooting - -If the eBPF collector does not work, you can troubleshoot it by running the `ebpf.plugin` command and investigating its -output. - -```bash -cd /usr/libexec/netdata/plugins.d/ -sudo su -s /bin/bash netdata -./ebpf.plugin -``` - -You can also use `grep` to search the Agent's `error.log` for messages related to eBPF monitoring. - -```bash -grep -i ebpf /var/log/netdata/error.log -``` +- `oom/mark_victim`: Monitors when an oomkill event happens. -### Confirm kernel compatibility +## Known issues -The eBPF collector only works on Linux systems and with specific Linux kernels. We support all kernels more recent than -`4.11.0`, and all kernels on CentOS 7.6 or later. - -You can run our helper script to determine whether your system can support eBPF monitoring. - -```bash -curl -sSL https://raw.githubusercontent.com/netdata/kernel-collector/master/tools/check-kernel-config.sh | sudo bash -``` - -If this script returns no output, your system is ready to compile and run the eBPF collector. - -If you see a warning about a missing kernel -configuration (`KPROBES KPROBES_ON_FTRACE HAVE_KPROBES BPF BPF_SYSCALL BPF_JIT`), you will need to recompile your kernel -to support this configuration. The process of recompiling Linux kernels varies based on your distribution and version. -Read the documentation for your system's distribution to learn more about the specific workflow for recompiling the -kernel, ensuring that you set all the necessary - -- [Ubuntu](https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel) -- [Debian](https://kernel-team.pages.debian.net/kernel-handbook/ch-common-tasks.html#s-common-official) -- [Fedora](https://fedoraproject.org/wiki/Building_a_custom_kernel) -- [CentOS](https://wiki.centos.org/HowTos/Custom_Kernel) -- [Arch Linux](https://wiki.archlinux.org/index.php/Kernel/Traditional_compilation) -- [Slackware](https://docs.slackware.com/howtos:slackware_admin:kernelbuilding) - -### Mount `debugfs` and `tracefs` - -The eBPF collector also requires both the `tracefs` and `debugfs` filesystems. Try mounting the `tracefs` and `debugfs` -filesystems using the commands below: - -```bash -sudo mount -t debugfs nodev /sys/kernel/debug -sudo mount -t tracefs nodev /sys/kernel/tracing -``` - -If they are already mounted, you will see an error. You can also configure your system's `/etc/fstab` configuration to -mount these filesystems on startup. More information can be found in -the [ftrace documentation](https://www.kernel.org/doc/Documentation/trace/ftrace.txt). - -## Performance +### Performance opimization eBPF monitoring is complex and produces a large volume of metrics. We've discovered scenarios where the eBPF plugin significantly increases kernel memory usage by several hundred MB. @@ -817,7 +870,7 @@ usage (see the `system.ram` chart) has dropped significantly. Beginning with `v1.31`, kernel memory usage is configurable via the [`pid table size` setting](#ebpf-load-mode) in `ebpf.conf`. -## SELinux +### SELinux When [SELinux](https://www.redhat.com/en/topics/linux/what-is-selinux) is enabled, it may prevent `ebpf.plugin` from starting correctly. Check the Agent's `error.log` file for errors like the ones below: @@ -837,7 +890,7 @@ ess.pl" exe="/usr/libexec/netdata/plugins.d/ebpf.plugin" subj=system_u:system_r: If you see similar errors, you will have to adjust SELinux's policies to enable the eBPF collector. -### Creation of bpf policies +#### Creation of bpf policies To enable `ebpf.plugin` to run on a distribution with SELinux enabled, it will be necessary to take the following actions. @@ -883,14 +936,14 @@ Finally, you can load the new policy and start the Netdata agent again: # systemctl start netdata ``` -## Lockdown +### Linux kernel lockdown Beginning with [version 5.4](https://www.zdnet.com/article/linux-to-get-kernel-lockdown-feature/), the Linux kernel has a feature called "lockdown," which may affect `ebpf.plugin` depending how the kernel was compiled. The following table shows how the lockdown module impacts `ebpf.plugin` based on the selected options: | Enforcing kernel lockdown | Enable lockdown LSM early in init | Default lockdown mode | Can `ebpf.plugin` run with this? | -|:------------------------- |:--------------------------------- |:--------------------- |:-------------------------------- | +| :------------------------ | :-------------------------------- | :-------------------- | :------------------------------- | | YES | NO | NO | YES | | YES | Yes | None | YES | | YES | Yes | Integrity | YES | @@ -898,5 +951,3 @@ shows how the lockdown module impacts `ebpf.plugin` based on the selected option If you or your distribution compiled the kernel with the last combination, your system cannot load shared libraries required to run `ebpf.plugin`. - -[](<>) |