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| wiki:system_configuration [2022/05/18 17:51] – [The kernel] autostatic | wiki:system_configuration [2022/06/05 11:46] – [cyclictest] autostatic |
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| Setting the ''noatime'' parameter in your ''/etc/fstab'' file reduces the amount of disk IO (the inode access times are not updated each time a file is read) which could improve the overall performance of your system. | Setting the ''noatime'' parameter in your ''/etc/fstab'' file reduces the amount of disk IO (the inode access times are not updated each time a file is read) which could improve the overall performance of your system. |
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| ''/dev/sdax / ext4 noatime,errors=remount-ro 0 1'' | /dev/sdax / ext4 noatime,errors=remount-ro 0 1 |
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| Most modern distributions use either ''atime'' or ''relatime''. See the mount manpage for more information on these parameters. | Most modern distributions use either ''atime'' or ''relatime''. See the mount manpage for more information on these parameters. |
| According to this thread [[http://comments.gmane.org/gmane.comp.file-systems.ext4/26720|High latency with ext4 / jbd2 kernel thread]] on the ext4 mailing list, the ''nobarrier'' parameter, with an ext4 filesystem, can reduce the amount of work made by the background kernel thread jbd2 and increase write speeds. However, this is an unsafe parameter, making your filesystem less resistant to power failures. | According to this thread [[http://comments.gmane.org/gmane.comp.file-systems.ext4/26720|High latency with ext4 / jbd2 kernel thread]] on the ext4 mailing list, the ''nobarrier'' parameter, with an ext4 filesystem, can reduce the amount of work made by the background kernel thread jbd2 and increase write speeds. However, this is an unsafe parameter, making your filesystem less resistant to power failures. |
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| ''/dev/sdax / ext4 nobarrier,errors=remount-ro 0 1'' | /dev/sdax / ext4 nobarrier,errors=remount-ro 0 1 |
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| Ext3 filesystem doesn't enable barrier by default, ext4 does. See the mount manpage for more information on these parameters. | Ext3 filesystem doesn't enable barrier by default, ext4 does. See the mount manpage for more information on these parameters. |
| ==== audio group ==== | ==== audio group ==== |
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| It is generally good practice to have an 'audio' group, and add any users that should be allowed to perform audio tasks to this group. This prevents some interference from non-audio-processes with audio tasks. To verify you're in the 'audio' group, run the ''groups'' command. Remember, after adding yourself to new groups, you need to log out and back in again. Be careful when adding an 'audio' group to your system: most systems come with a pre-configured 'audio' group, and do not warn you when you add another group with the same name, leading to much confusion. | It is generally good practice to have an ''audio'' group, and add any users that should be allowed to perform audio tasks to this group. This prevents some interference from non-audio-processes with audio tasks. To verify you're in the ''audio'' group, run the ''groups'' command. Remember, after adding yourself to new groups, you need to log out and back in again. Be careful when adding an ''audio'' group to your system: most systems come with a pre-configured ''audio'' group, and do not warn you when you add another group with the same name, leading to much confusion. When using Arch Linux the above is valid too except that Arch uses a different group name, i.e. ''realtime''((https://wiki.archlinux.org/title/Realtime_process_management#Configuring_PAM)). |
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| ==== Timers ==== | ==== Timers ==== |
| ==== cyclictest ==== | ==== cyclictest ==== |
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| Just as ''latencytop'' measures system latencies, ''[[https://rt.wiki.kernel.org/index.php/Cyclictest|cyclictest]]'' measures kernel latencies. ''cyclictest'' has quite some options but one of the most used ways to run the command is: | Just as ''latencytop'' measures system latencies, ''[[https://wiki.linuxfoundation.org/realtime/documentation/howto/tools/cyclictest/start|cyclictest]]'' measures kernel latencies. ''cyclictest'' has quite some options but one of the most used ways to run the command is: |
| # cyclictest -t1 -p 80 -n -i 10000 -l 10000 -m | # cyclictest -t1 -p 80 -n -i 10000 -l 10000 -m |
| One single thread (''-t1''), priority of 80 (''-p 80''), use clock_nanosleep (''-n''), use 10000 us base interval of thread (''-i 1000''), use 1000 loops and then exit (''-l 10000''), lock current and future memory allocations (''-m''). More on clock_nanosleep can be found in its manpage (''man clock_nanosleep''). | One single thread (''-t1''), priority of 80 (''-p 80''), use clock_nanosleep (''-n''), use 10000 us base interval of thread (''-i 1000''), use 1000 loops and then exit (''-l 10000''), lock current and future memory allocations (''-m''). More on clock_nanosleep can be found in its manpage (''man clock_nanosleep''). |
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| Other examples of the usage of ''cyclictest'': | Other examples of the usage of ''cyclictest'': |
| * http://code.goto10.org/projects/puredyne-old/wiki/KernelAndSystemOptimization#TestingandBenchmarking | * https://web.archive.org/web/20130727095507/http://code.goto10.org/projects/puredyne-old/wiki/KernelAndSystemOptimization#TestingandBenchmarking |
| * https://rt.wiki.kernel.org/index.php/Cyclictest#Expected_Results | * https://wiki.linuxfoundation.org/realtime/documentation/howto/tools/cyclictest/result-examples |
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| ===== TODO ===== | ===== TODO ===== |
