diff options
Diffstat (limited to 'health/guides/ipc')
| -rw-r--r-- | health/guides/ipc/semaphore_arrays_used.md | 46 | ||||
| -rw-r--r-- | health/guides/ipc/semaphores_used.md | 48 |
2 files changed, 94 insertions, 0 deletions
diff --git a/health/guides/ipc/semaphore_arrays_used.md b/health/guides/ipc/semaphore_arrays_used.md new file mode 100644 index 000000000..d12dacd47 --- /dev/null +++ b/health/guides/ipc/semaphore_arrays_used.md @@ -0,0 +1,46 @@ +### Understand the alert + +This alarm monitors the percentage of used `System V IPC semaphore arrays (sets)`. If you receive this alert, it means that your system has a high utilization of `IPC semaphore arrays`, which can affect application performance. + +### Troubleshoot the alert + +1. Check the current usage of semaphore arrays + + Use the `ipcs -u` command to display a summary of the current usage of semaphore arrays on your system. Look for the "allocated semaphores" section, which indicates the number of semaphore arrays being used. + + ``` + ipcs -u + ``` + +2. Identify processes using semaphore arrays + + Use the `ipcs -s` command to list all active semaphore arrays and their associated process IDs (PIDs). This information can help you identify which processes are using semaphore arrays. + + ``` + ipcs -s + ``` + +3. Investigate and optimize processes using semaphore arrays + + Based on the information from the previous step, investigate the processes that are using semaphore arrays. If any of these processes can be optimized or terminated to free up semaphore arrays, do so carefully after ensuring that they are not critical to your system. + +4. Adjust the semaphore limit on your system + + If the semaphore array usage is still high after optimizing processes, you may need to increase the semaphore limit on your system. As mentioned earlier, you can adjust the limit in the `/proc/sys/kernel/sem` file. + + ``` + vi /proc/sys/kernel/sem + ``` + + Edit the fourth field to increase the max semaphores limit. Save the file and exit. To apply the changes, run: + + ``` + sysctl -p + ``` + + Please note that increasing the limit might consume more system resources. Monitor your system closely to ensure that it remains stable after making these changes. + +### Useful resources + +1. [Interprocess Communication](https://docs.oracle.com/cd/E19455-01/806-4750/6jdqdfltn/index.html) +2. [IPC: Semaphores](https://users.cs.cf.ac.uk/Dave.Marshall/C/node26.html) diff --git a/health/guides/ipc/semaphores_used.md b/health/guides/ipc/semaphores_used.md new file mode 100644 index 000000000..145ef0ad4 --- /dev/null +++ b/health/guides/ipc/semaphores_used.md @@ -0,0 +1,48 @@ +### Understand the alert + +This alert monitors the percentage of allocated `System V IPC semaphores`. If you receive this alert, it means that your system is experiencing high IPC semaphore utilization, and a lack of available semaphores can affect application performance. + +### Troubleshoot the alert + +1. Identify processes using IPC semaphores + + You can use the `ipcs` command to display information about allocated semaphores. Run the following command to display a list of active semaphores: + + ``` + ipcs -s + ``` + + The output will show the key, ID, owner's UID, permissions, and other related information for each semaphore. + +2. Analyze process usage of IPC semaphores + + You can use `ps` or `top` commands to analyze which processes are using the IPC semaphores. This can help you identify if any process is causing high semaphore usage. + + ``` + ps -eo pid,cmd | grep [process-name] + ``` + + Replace `[process-name]` with the name of the process you suspect is related to the semaphore usage. + +3. Adjust semaphore limits if necessary + + If you determine that the high semaphore usage is a result of an inadequately configured limit, you can update the limits using the following steps: + + - Check the current semaphore limits as mentioned earlier, using the `ipcs -ls` command. + - To increase the limit to a more appropriate value, edit the `/proc/sys/kernel/sem` file. The second field in the file represents the maximum number of semaphores that can be allocated per array. + + ``` + echo "32000 64000 1024000000 500" > /proc/sys/kernel/sem + ``` + + This command doubles the number of semaphores per array. Make sure to adjust the value according to your system requirements. + +4. Monitor semaphore usage after changes + + After making the necessary changes, continue to monitor semaphore usage to ensure that the changes were effective in resolving the issue. If the issue persists, further investigation may be required to identify the root cause. + +### Useful resources + +1. [Interprocess Communication](https://docs.oracle.com/cd/E19455-01/806-4750/6jdqdfltn/index.html) +2. [IPC: Semaphores](https://users.cs.cf.ac.uk/Dave.Marshall/C/node26.html) +3. [Linux Kernel Documentation - IPC Semaphores](https://www.kernel.org/doc/Documentation/ipc/semaphore.txt)
\ No newline at end of file |