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kernelOfTruth
Watchman
Joined: 20 Dec 2005
Posts: 6111
Location: Vienna, Austria; Germany; hello world :)
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 Posted: Fri Jul 10, 2015 8:26 pm Post subject: Realtime & Low-latency scheduling (Gaming, Pro-Audio, et |
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Hi guys,
[WIP]
This is mainly a stub for now and is mostly tailored towards CFS
here's a incomplete list of settings to set up to get a nice low-latency response from your system.
The intention to get this kind of behavior can be to do Gaming on Linux - either native (e.g. via Steam) or WINE (e.g. Crysis, Mass Effect 3 [with or without MultiPlayer], etc.)
or tasks that require that the system is processing load in a deadline-like fashion.
kernel-related settings:
run the kernel with
threadirqs
appended to your bootloader
For CFS (classical, vanilla) CPU scheduler
| Code: | zgrep GROUP /proc/config.gz
CONFIG_CGROUPS=y
CONFIG_CGROUP_DEBUG=y
CONFIG_CGROUP_FREEZER=y
# CONFIG_CGROUP_DEVICE is not set
CONFIG_CGROUP_CPUACCT=y
# CONFIG_CGROUP_HUGETLB is not set
CONFIG_CGROUP_PERF=y
CONFIG_CGROUP_SCHED=y
CONFIG_FAIR_GROUP_SCHED=y
CONFIG_RT_GROUP_SCHED=y
CONFIG_BLK_CGROUP=y
# CONFIG_DEBUG_BLK_CGROUP is not set
CONFIG_SCHED_AUTOGROUP=y
CONFIG_CFQ_GROUP_IOSCHED=y
CONFIG_CGROUP_BFQIO=y
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For BFS (tweaked, aka "beefy") CPU scheduler
...
fixme
Scheduler behavior related changes (general):
General scheduler changes for CFS:
| Code: | echo "6000000" > /proc/sys/kernel/sched_latency_ns
echo "100000" > /proc/sys/kernel/sched_min_granularity_ns
echo "10000" > /proc/sys/kernel/sched_wakeup_granularity_ns
echo "7000000" > /proc/sys/kernel/sched_migration_cost_ns
echo "8" > /proc/sys/kernel/sched_nr_migrate
echo "80000" > /proc/sys/kernel/sched_shares_window_ns
echo "970000" > /proc/sys/kernel/sched_rt_runtime_us
echo "1000000" > /proc/sys/kernel/sched_rt_period_us |
General scheduler changes for BFS:
| Code: | echo "4" > /proc/sys/kernel/rr_interval
echo "85" > /proc/sys/kernel/iso_cpu |
IRQ-related tweaking:
Sample:
| Code: | #!/bin/bash
# Sorted view:
# ps -eLo rtprio,cls,pid,pri,nice,cmd | grep "FF" | sort -r
# ps -eLo pid,cls,rtprio,pri,nice,cmd | grep -i "irq"
# For a non-RT kernel, use kernel option: threadirqs
# http://subversion.ffado.org/wiki/IrqPriorities
# http://alsa.opensrc.org/Rtirq
#piwl=$(pgrep "irq/.*-iwlwifi")
#[[ -n $piwl ]] && chrt -f -p 10 $piwl
#peth=$(pgrep "irq/.*-eth0")
#[[ -n $peth ]] && chrt -f -p 30 $peth
#peth=$(pgrep "irq/.*-eth1")
#[[ -n $peth ]] && chrt -f -p 30 $peth
peth=$(pgrep "irq/.*-eth")
[[ -n $peth ]] && chrt -f -p 50 $peth
# ehci instead of uhci
pmouse=$(pgrep "irq/23-ehci")
[[ -n $pmouse ]] && chrt -f -p 59 $pmouse
pmouse=$(pgrep "irq/20-ehci")
[[ -n $pmouse ]] && chrt -f -p 59 $pmouse
#pmouse=$(pgrep "irq/19-uhci")
#[[ -n $pmouse ]] && chrt -f -p 59 $pmouse
psnd=$(pgrep "irq/.*-snd_")
[[ -n $psnd ]] && chrt -f -p 85 $psnd
#pnouveau=$(pgrep "irq/.*-nouveau")
#[[ -n $pnouveau ]] && chrt -f -p 80 $pnouveau
pnvkm=$(pgrep "irq/.*-nvkm")
[[ -n $pnvkm ]] && chrt -f -p 84 $pnvkm
pnvidia=$(pgrep "irq/.*-nvidia")
[[ -n $pnvkm ]] && chrt -f -p 84 $pnvidia
#pkbd=$(pgrep "irq/.*-i8042")
## 2 of them
#for p in $pkbd ; do
# chrt -f -p 60 $p
#done
prtc=$(pgrep "irq/.*-rtc0")
[[ -n $prtc ]] && chrt -f -p 90 $prtc
#( while true ; do
# # Does not have an IRQ until Xorg is running
# pnvidia=$(pgrep "irq/.*-nvidia")
# if [[ -n $pnvidia ]] ; then
# chrt -f -p 80 $pnvidia
# break
# fi
# sleep 20
#done ) &
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priority for the nvidia kernel-module doesn't seem to get changed thus - I'll usually do it manually:
| Code: | | ps -eLo rtprio,cls,pid,pri,nice,cmd | grep "FF" | sort -r |
<-- look for nvidia
| Quote: | | 50 FF 13613 90 - [irq/39-nvidia] |
so
| Code: | | chrt -f -p 84 13613 |
software-related tweaking:
Giving the X-server some more bite:
| Code: | | chrt -a -p -r 9 `pidof X` |
check in htop or top afterwards whether priority got raised to -10
Gaming and app-related tweaking:
Running WINE ?
| Code: | | schedtool -R -p 90 $(pidof wineserver) |
and on top of that Mass Effect 3 Multiplayer ?
| Code: | | ps aux | grep MassEffect3.exe |
Does it e.g. reveal 15436 as PID ?
| Code: | | chrt -a -p -r 89 15436 |
WINE-related considerations:
Make sure to emerge WINE with the staging-USE-flag
and enable CSMT-support in winecfg
Results:
(especially)
Mass Effect 3 Multiplayer
and
Borderlands2
run way much smoother than before !
Borderlands runs flawlessly (at least the native port launched from within Steam)
and
ME3 MP runs 75-95% (in my impression) at speed.
You might need to disable dynamic shadows and AA, do a little tweaking in the GameSettings.ini
but overall it runs surprisingly well.
1920x1080 vs. 1920x1080 in Windows
Whereas previously I couldn't bear to do several rounds on Linux - so only as a occasional bite
it now could prevent me from booting into Windows 
Acknowledgements:
- PaulBredbury https://forums.gentoo.org/viewtopic-p-7153966.html#7153966
You ROCK 
- Rookie1337 http://www.overclock.net/t/1519964/experiment-overclocking-the-linux-os-through-the-sysclt-proc-sys-sys-block-and-other-settings#post_23094293
That's some sick well-documented shift 
- All Gentooligans
Ricers UNITE ! 
_________________
https://github.com/kernelOfTruth/ZFS-for-SystemRescueCD/tree/ZFS-for-SysRescCD-4.9.0
https://github.com/kernelOfTruth/pulseaudio-equalizer-ladspa
Hardcore Gentoo Linux user since 2004 |
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joe4379
n00b
Joined: 19 Jan 2015
Posts: 7
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| Posted: Thu Dec 01, 2016 4:38 pm Post subject: thanks, and a script |
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Thanks! This is huge! 
I made a script to semi-automate setting the Nvidia priority (nothing to remember at least). It has sudos and i dont care...
| Code: | GNU nano 2.7.1 File: /usr/bin/tweaks
sudo chrt -a -p -r 9 `pidof X`
#[[ -n $pnvkm ]] && chrt -f -p 84 $pnvidia
ps -eLo rtprio,cls,pid,pri,nice,cmd | grep "FF" | sort -r |grep nvidia
echo "What's the third number (PID of nVidia IRQ)?"
read -e PIDOFNVIDIA
sudo chrt -f -p 84 $PIDOFNVIDIA
chrt -p $PIDOFNVIDIA
echo "100000" | sudo tee /proc/sys/kernel/sched_latency_ns
echo "100000" | sudo tee /proc/sys/kernel/sched_min_granularity_ns
echo "1000" | sudo tee /proc/sys/kernel/sched_wakeup_granularity_ns
echo "25000" | sudo tee /proc/sys/kernel/sched_migration_cost_ns
echo "4" | sudo tee /proc/sys/kernel/sched_nr_migrate
echo 1024 | sudo tee /proc/sys/kernel/msgmax && echo 2048 | sudo tee /proc/sys/kernel/msgmnb && echo 8192 | sudo tee /proc/sys/kernel/msgmni
echo "990000" | sudo tee /proc/sys/kernel/sched_rt_runtime_us
echo "1000000" | sudo tee /proc/sys/kernel/sched_rt_period_us
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timofonic
n00b
Joined: 13 Sep 2005
Posts: 16
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| Posted: Sun Dec 11, 2016 12:59 pm Post subject: Re: thanks, and a script |
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Hello.
Nvidia proprietary support for this? Thanks a lot! My laptop will be very happy (I plan to install Gentoo on a laptop, I'll have a big workstation later).
It could be nice to standarize the process, make a github.com repository and a package and publish it in Gentoo wiki. This way, realtime and low latency could be more easily adopted. Even better, a database of tweaks for different apps could be made and including Wine software too.
Really: Why isn't realtime and low latency options part of a default Linux desktop installation? I tired it a few times and the results are amazing from my point of view, but the process is really quite cumbersome.
Kind regards.
| joe4379 wrote: | Thanks! This is huge!
I made a script to semi-automate setting the Nvidia priority (nothing to remember at least). It has sudos and i dont care...
| Code: |
sudo chrt -a -p -r 9 `pidof X`
#[[ -n $pnvkm ]] && chrt -f -p 84 $pnvidia
ps -eLo rtprio,cls,pid,pri,nice,cmd | grep "FF" | sort -r |grep nvidia
echo "What's the third number (PID of nVidia IRQ)?"
read -e PIDOFNVIDIA
sudo chrt -f -p 84 $PIDOFNVIDIA
chrt -p $PIDOFNVIDIA
echo "100000" | sudo tee /proc/sys/kernel/sched_latency_ns
echo "100000" | sudo tee /proc/sys/kernel/sched_min_granularity_ns
echo "1000" | sudo tee /proc/sys/kernel/sched_wakeup_granularity_ns
echo "25000" | sudo tee /proc/sys/kernel/sched_migration_cost_ns
echo "4" | sudo tee /proc/sys/kernel/sched_nr_migrate
echo 1024 | sudo tee /proc/sys/kernel/msgmax && echo 2048 | sudo tee /proc/sys/kernel/msgmnb && echo 8192 | sudo tee /proc/sys/kernel/msgmni
echo "990000" | sudo tee /proc/sys/kernel/sched_rt_runtime_us
echo "1000000" | sudo tee /proc/sys/kernel/sched_rt_period_us
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