diff options
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/fprobetrace.rst | 4 | ||||
| -rw-r--r-- | Documentation/trace/ftrace.rst | 2 | ||||
| -rw-r--r-- | Documentation/trace/hisi-ptt.rst | 4 | ||||
| -rw-r--r-- | Documentation/trace/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/trace/kprobes.rst | 1 | ||||
| -rw-r--r-- | Documentation/trace/kprobetrace.rst | 10 | ||||
| -rw-r--r-- | Documentation/trace/ring-buffer-map.rst | 106 | ||||
| -rw-r--r-- | Documentation/trace/tracepoints.rst | 2 |
8 files changed, 121 insertions, 9 deletions
diff --git a/Documentation/trace/fprobetrace.rst b/Documentation/trace/fprobetrace.rst index 0f187e3796..b4c2ca3d02 100644 --- a/Documentation/trace/fprobetrace.rst +++ b/Documentation/trace/fprobetrace.rst @@ -74,7 +74,7 @@ Function arguments at exit -------------------------- Function arguments can be accessed at exit probe using $arg<N> fetcharg. This is useful to record the function parameter and return value at once, and -trace the difference of structure fields (for debuging a function whether it +trace the difference of structure fields (for debugging a function whether it correctly updates the given data structure or not) See the :ref:`sample<fprobetrace_exit_args_sample>` below for how it works. @@ -248,4 +248,4 @@ mode. You can trace that changes with return probe. cat-143 [007] ...1. 1945.720616: vfs_open__entry: (vfs_open+0x4/0x40) mode=0x1 inode=0x0 cat-143 [007] ...1. 1945.728263: vfs_open__exit: (do_open+0x274/0x3d0 <- vfs_open) mode=0xa800d inode=0xffff888004ada8d8 -You can see the `file::f_mode` and `file::f_inode` are upated in `vfs_open()`. +You can see the `file::f_mode` and `file::f_inode` are updated in `vfs_open()`. diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index 7e7b8ec179..5aba74872b 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -1968,7 +1968,7 @@ wakeup One common case that people are interested in tracing is the time it takes for a task that is woken to actually wake up. Now for non Real-Time tasks, this can be arbitrary. But tracing -it none the less can be interesting. +it nonetheless can be interesting. Without function tracing:: diff --git a/Documentation/trace/hisi-ptt.rst b/Documentation/trace/hisi-ptt.rst index 989255eb56..6eef28ebb0 100644 --- a/Documentation/trace/hisi-ptt.rst +++ b/Documentation/trace/hisi-ptt.rst @@ -40,7 +40,7 @@ IO dies (SICL, Super I/O Cluster), where there's one PCIe Root Complex for each SICL. :: - /sys/devices/hisi_ptt<sicl_id>_<core_id> + /sys/bus/event_source/devices/hisi_ptt<sicl_id>_<core_id> Tune ==== @@ -53,7 +53,7 @@ Each event is presented as a file under $(PTT PMU dir)/tune, and a simple open/read/write/close cycle will be used to tune the event. :: - $ cd /sys/devices/hisi_ptt<sicl_id>_<core_id>/tune + $ cd /sys/bus/event_source/devices/hisi_ptt<sicl_id>_<core_id>/tune $ ls qos_tx_cpl qos_tx_np qos_tx_p tx_path_rx_req_alloc_buf_level diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst index 5092d6c13a..0b300901fd 100644 --- a/Documentation/trace/index.rst +++ b/Documentation/trace/index.rst @@ -29,6 +29,7 @@ Linux Tracing Technologies timerlat-tracer intel_th ring-buffer-design + ring-buffer-map stm sys-t coresight/index diff --git a/Documentation/trace/kprobes.rst b/Documentation/trace/kprobes.rst index e1636e579c..5e606730ce 100644 --- a/Documentation/trace/kprobes.rst +++ b/Documentation/trace/kprobes.rst @@ -322,6 +322,7 @@ architectures: - s390 - parisc - loongarch +- riscv Configuring Kprobes =================== diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst index a49662ccd5..3b6791c17e 100644 --- a/Documentation/trace/kprobetrace.rst +++ b/Documentation/trace/kprobetrace.rst @@ -58,8 +58,9 @@ Synopsis of kprobe_events NAME=FETCHARG : Set NAME as the argument name of FETCHARG. FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types - (x8/x16/x32/x64), "char", "string", "ustring", "symbol", "symstr" - and bitfield are supported. + (x8/x16/x32/x64), VFS layer common type(%pd/%pD), "char", + "string", "ustring", "symbol", "symstr" and bitfield are + supported. (\*1) only for the probe on function entry (offs == 0). Note, this argument access is best effort, because depending on the argument type, it may be passed on @@ -74,7 +75,7 @@ Function arguments at kretprobe ------------------------------- Function arguments can be accessed at kretprobe using $arg<N> fetcharg. This is useful to record the function parameter and return value at once, and -trace the difference of structure fields (for debuging a function whether it +trace the difference of structure fields (for debugging a function whether it correctly updates the given data structure or not). See the :ref:`sample<fprobetrace_exit_args_sample>` in fprobe event for how it works. @@ -122,6 +123,9 @@ With 'symstr' type, you can filter the event with wildcard pattern of the symbols, and you don't need to solve symbol name by yourself. For $comm, the default type is "string"; any other type is invalid. +VFS layer common type(%pd/%pD) is a special type, which fetches dentry's or +file's name from struct dentry's address or struct file's address. + .. _user_mem_access: User Memory Access diff --git a/Documentation/trace/ring-buffer-map.rst b/Documentation/trace/ring-buffer-map.rst new file mode 100644 index 0000000000..8e296bcc0d --- /dev/null +++ b/Documentation/trace/ring-buffer-map.rst @@ -0,0 +1,106 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================================== +Tracefs ring-buffer memory mapping +================================== + +:Author: Vincent Donnefort <vdonnefort@google.com> + +Overview +======== +Tracefs ring-buffer memory map provides an efficient method to stream data +as no memory copy is necessary. The application mapping the ring-buffer becomes +then a consumer for that ring-buffer, in a similar fashion to trace_pipe. + +Memory mapping setup +==================== +The mapping works with a mmap() of the trace_pipe_raw interface. + +The first system page of the mapping contains ring-buffer statistics and +description. It is referred to as the meta-page. One of the most important +fields of the meta-page is the reader. It contains the sub-buffer ID which can +be safely read by the mapper (see ring-buffer-design.rst). + +The meta-page is followed by all the sub-buffers, ordered by ascending ID. It is +therefore effortless to know where the reader starts in the mapping: + +.. code-block:: c + + reader_id = meta->reader->id; + reader_offset = meta->meta_page_size + reader_id * meta->subbuf_size; + +When the application is done with the current reader, it can get a new one using +the trace_pipe_raw ioctl() TRACE_MMAP_IOCTL_GET_READER. This ioctl also updates +the meta-page fields. + +Limitations +=========== +When a mapping is in place on a Tracefs ring-buffer, it is not possible to +either resize it (either by increasing the entire size of the ring-buffer or +each subbuf). It is also not possible to use snapshot and causes splice to copy +the ring buffer data instead of using the copyless swap from the ring buffer. + +Concurrent readers (either another application mapping that ring-buffer or the +kernel with trace_pipe) are allowed but not recommended. They will compete for +the ring-buffer and the output is unpredictable, just like concurrent readers on +trace_pipe would be. + +Example +======= + +.. code-block:: c + + #include <fcntl.h> + #include <stdio.h> + #include <stdlib.h> + #include <unistd.h> + + #include <linux/trace_mmap.h> + + #include <sys/mman.h> + #include <sys/ioctl.h> + + #define TRACE_PIPE_RAW "/sys/kernel/tracing/per_cpu/cpu0/trace_pipe_raw" + + int main(void) + { + int page_size = getpagesize(), fd, reader_id; + unsigned long meta_len, data_len; + struct trace_buffer_meta *meta; + void *map, *reader, *data; + + fd = open(TRACE_PIPE_RAW, O_RDONLY | O_NONBLOCK); + if (fd < 0) + exit(EXIT_FAILURE); + + map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0); + if (map == MAP_FAILED) + exit(EXIT_FAILURE); + + meta = (struct trace_buffer_meta *)map; + meta_len = meta->meta_page_size; + + printf("entries: %llu\n", meta->entries); + printf("overrun: %llu\n", meta->overrun); + printf("read: %llu\n", meta->read); + printf("nr_subbufs: %u\n", meta->nr_subbufs); + + data_len = meta->subbuf_size * meta->nr_subbufs; + data = mmap(NULL, data_len, PROT_READ, MAP_SHARED, fd, meta_len); + if (data == MAP_FAILED) + exit(EXIT_FAILURE); + + if (ioctl(fd, TRACE_MMAP_IOCTL_GET_READER) < 0) + exit(EXIT_FAILURE); + + reader_id = meta->reader.id; + reader = data + meta->subbuf_size * reader_id; + + printf("Current reader address: %p\n", reader); + + munmap(data, data_len); + munmap(meta, meta_len); + close (fd); + + return 0; + } diff --git a/Documentation/trace/tracepoints.rst b/Documentation/trace/tracepoints.rst index 0cb8d9ca3d..decabcc77b 100644 --- a/Documentation/trace/tracepoints.rst +++ b/Documentation/trace/tracepoints.rst @@ -27,7 +27,7 @@ the tracepoint site). You can put tracepoints at important locations in the code. They are lightweight hooks that can pass an arbitrary number of parameters, -which prototypes are described in a tracepoint declaration placed in a +whose prototypes are described in a tracepoint declaration placed in a header file. They can be used for tracing and performance accounting. |