Originally posted by Linuxxx
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Benchmarking Ubuntu's Low-Latency Kernel & Liquorix Post-Meltdown
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The 'perf' test results vary by about three tenths of a millisecond over these kernels.
I don't think that test says anything meaningful and it should be discarded as 'win' or a 'loss'.
Time accounting precision in these kernels might vary by that amount (?) - anyone care to enlighten me on that thought.
In a practical sense, 3 tenths of a ms wont keep us awake at night.
$time ls /usr/bin varies by more. Does the test really do anything but return?
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Originally posted by LuukD View PostThe 'perf' test results vary by about three tenths of a millisecond over these kernels.
I don't think that test says anything meaningful and it should be discarded as 'win' or a 'loss'.
Time accounting precision in these kernels might vary by that amount (?) - anyone care to enlighten me on that thought.
In a practical sense, 3 tenths of a ms wont keep us awake at night.
$time ls /usr/bin varies by more. Does the test really do anything but return?
I would like to see a programatic way to see if something won or loss by "an inch or a mile"
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Originally posted by Linuxxx View PostHere's how one can achieve real smoothness:
- Use openSUSE Tumbleweed, since it contains the best Linux Kernel config by default. (250Hz tick timer, PREEMPT enabled)
- Use the deadline İO scheduler.
- Use the 'performance' governor.
- Additionally, if stuck on İntel, make sure to set the 'performance-bias' to '0'!
Now enjoy your silky-smooth Linux experience!
and FYI, any desktop or mobile linux kernel is mostly going to be preempt. pretty standard stuff.
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Originally posted by Licaon View PostSpectre/Meltdown appear to (mostly) not affect games.
Or were you talking about Liquorix and kernel latency in general?
I found some results here: https://docs.google.com/spreadsheets...E-w/edit#gid=0
some examples: GTX 970 averages 34ms (23-47ms), HD5770 was worse at about 47ms (36-56ms). both on an ASUS VG248QE monitor at 120Hz and Intel G4560 CPU.
I guess this is all a bit off-topic, but the generic vs low-latency vs Liquorix comparisons got me going.
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Originally posted by RelaxTrolls View Post
using the performance governor is handy for some use cases, mainly since you'll avoid CPU scaling... but using it all the time seems like bad advice... especially on any device where you care about power-saving or temperatures ....
and FYI, any desktop or mobile linux kernel is mostly going to be preempt. pretty standard stuff.
Case in point: Even a passively cooled Notebook remains cool under normal usage.
Also, about this all being pretty standard stuff:
Go ahead and tell that to Red Hat (Fedora), Debian & Ubuntu!
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Originally posted by Spooktra View Post
How exactly do you do the above?
Code:cat << EOF | sudo tee /etc/systemd/system/performance.service [Unit] Description=CPU performance [Service] Type=oneshot ExecStart=/usr/bin/cpupower -c all frequency-set -g performance [Install] WantedBy=multi-user.target EOF
Code:cat << EOF | sudo tee /etc/systemd/system/bias.service [Unit] Description=CPU bias [Service] Type=oneshot ExecStart=/usr/bin/cpupower -c all set --perf-bias 0 [Install] WantedBy=multi-user.target EOF
Code:sudo systemctl enable performance.service sudo systemctl enable bias.service
For deadline IO scheduler, add this to your GRUB Kernel command line:
Code:elevator=deadline
Code:scsi_mod.use_blk_mq=1 elevator=bfq
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Originally posted by Linuxxx View Post
Performance governor:
Code:cat << EOF | sudo tee /etc/systemd/system/performance.service [Unit] Description=CPU performance [Service] Type=oneshot ExecStart=/usr/bin/cpupower -c all frequency-set -g performance [Install] WantedBy=multi-user.target EOF
Code:cat << EOF | sudo tee /etc/systemd/system/bias.service [Unit] Description=CPU bias [Service] Type=oneshot ExecStart=/usr/bin/cpupower -c all set --perf-bias 0 [Install] WantedBy=multi-user.target EOF
Code:sudo systemctl enable performance.service sudo systemctl enable bias.service
For deadline IO scheduler, add this to your GRUB Kernel command line:
Code:elevator=deadline
Code:scsi_mod.use_blk_mq=1 elevator=bfq
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