Difference between revisions of "Gaming"

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[[Category:Gaming (English)]]
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[[Category:Gaming]]
{{i18n|Gaming}}
+
[[da:Games]]
 
+
[[it:Games]]
 +
[[lt:Games]]
 +
[[ru:Gaming]]
 
{{Article summary start}}
 
{{Article summary start}}
 
{{Article summary text|Provides information about running games and related system configuration tips.}}
 
{{Article summary text|Provides information about running games and related system configuration tips.}}
 
{{Article summary heading|Related}}
 
{{Article summary heading|Related}}
{{Article summary wiki|Common Applications/Games}}
+
{{Article summary wiki|List of Applications/Games}}
 
{{Article summary wiki|Netbook Games}}
 
{{Article summary wiki|Netbook Games}}
 
{{Article summary wiki|Xorg}}
 
{{Article summary wiki|Xorg}}
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{{Article summary end}}
 
{{Article summary end}}
  
This page only contains information about running games and related system configuration tips. For lists of popular games for GNU/Linux see [[Common Applications/Games]] and [[Netbook Games]].
+
This page only contains information about running games and related system configuration tips. For lists of popular games for GNU/Linux see [[List of Applications/Games]] and [[Netbook Games]].
  
 
== Game Environments ==
 
== Game Environments ==
Line 18: Line 20:
  
 
* Native – Games written for Linux (usually Free & Open Source).
 
* Native – Games written for Linux (usually Free & Open Source).
* Browser – you need only browser and Internet connection to play this games.
+
* Browser – you need only browser and Internet connection to play these types of games.
 
** Plugin-based – you need to install plugin to play.
 
** Plugin-based – you need to install plugin to play.
*** [[Java]] Webstart – to install cross-platform games very easily.
+
*** [[Java]] Webstart – used to install cross-platform games very easily.
 
*** [[Flash]] games are very common on the Web.
 
*** [[Flash]] games are very common on the Web.
*** Unity – specialized plugin for browser, currently works only in [[Google Chrome]]. Most games are commercial.
+
*** Unity – specialized game plugin for browsers. Currently works only in Google Chrome. Most games are commercial and/or closed-source.
 
** '''HTML 5''' games use brand new canvas and WebGL technologies and work in all modern browsers but can be '''very''' slow on weak machines.
 
** '''HTML 5''' games use brand new canvas and WebGL technologies and work in all modern browsers but can be '''very''' slow on weak machines.
* Specialized environments (software emulators) – you should first install emulator, then find games yourself (most are protected by Copyright!)
+
* Specialized environments (software emulators) – – Required for running software designed for other architectures or systems (Heed the copyright laws of your country!)
** [[Wine]] – allows running of some Windows games.
+
** [[Wine]] – allows running of some Windows games, as well as a large amount of Windows software.
** [http://www.codeweavers.com/ Crossover Games] - members of the Codeweavers team are prime supporters of Wine. Using Crossover Games makes the installation & setting up of some games easier, more reliable & even possible, when compared to using other methods.  Crossover is an inexpensive commercial product, which also provides a [http://www.codeweavers.com/support/forums/ forum] where the developers are very much involved in the community.   
+
** [http://www.codeweavers.com/ Crossover Games] – members of the Codeweavers team are prime supporters of Wine. Using Crossover Games makes the installation & setting up of some games easier, more reliable & even possible, when compared to using other methods.  Crossover is a paid commercial product, which also provides a [http://www.codeweavers.com/support/forums/ forum] where the developers are very much involved in the community.   
 
** [[Cedega]] – game-oriented Wine derivative. Its packaged version is not free of charge unlike its CVS version.
 
** [[Cedega]] – game-oriented Wine derivative. Its packaged version is not free of charge unlike its CVS version.
** [[DosBox]] – DOS games
+
** [[DosBox]] – DOS emulator
** [[ScummVM]] – lots of old adventure games
+
** {{Pkg|scummvm}} – emulates games based on the [[Wikipedia:SCUMM|SCUMM game engine]], which ran many classic adventure games.
 
* Hardware emulators – emulate the whole device instead of software environment. The same thing about Copyright here.
 
* Hardware emulators – emulate the whole device instead of software environment. The same thing about Copyright here.
  
 
== Getting games ==
 
== Getting games ==
 
=== Native ===
 
=== Native ===
A good number are available in the [[Official repositories]] or in the [[AUR]].  [[Loki]] provides installers for several games. [[Desura]] can be considered good source of games (if you don't care about security and bugs too much).
+
A good number are available in the [[Official repositories]] or in the [[AUR]].  [http://liflg.org/ Loki] provides installers for several games. [http://desura.com Desura] can be considered good source of games (if you don't care about security and bugs too much).
  
 
=== Wine ===
 
=== Wine ===
* Centralized source of information about running games (and other applications) in Wine is [http://appdb.winehq.org/%7CWine AppDB].
+
* Centralized source of information about running games (and other applications) in Wine is [http://appdb.winehq.org/ Wine AppDB].
* See also [[Category:Wine_(English)]].
+
* See also [[:Category:Wine]].
  
 
=== Flash ===
 
=== Flash ===
Line 56: Line 58:
  
 
=== Multi-screen setups ===
 
=== Multi-screen setups ===
Running a multi-screen setup may lead to problems with fullscreen games. In such a case, [[#Starting_games_in_a_seperate_X_server|running a second X server]] is one possible solution. Another solution may be found in the [[NVIDIA#Gaming_using_Twinview|NVIDIA article]] (may also apply to non-NVIDIA users).
+
Running a multi-screen setup may lead to problems with fullscreen games. In such a case, [[#Starting games in a separate X server|running a second X server]] is one possible solution. Another solution may be found in the [[NVIDIA#Gaming_using_Twinview|NVIDIA article]] (may also apply to non-NVIDIA users).
  
 
=== Keyboard Grabbing ===
 
=== Keyboard Grabbing ===
Some games grab the keyboard, noticeably preventing you from switching windows (also known as alt-tabbing). Download [http://aur.archlinux.org/packages.php?ID=23052 sdl-nokeyboardgrab] to gain the ability to use keyboard commands while in SDL games. If you wish to turn it up to 11, you can disable keyboard grabbing at X11 level using [http://aur.archlinux.org/packages.php?ID=39351 libx11-nokeyboardgrab].
+
Many games grab the keyboard, noticeably preventing you from switching windows (also known as alt-tabbing). Download {{AUR|sdl-nokeyboardgrab}} to gain the ability to use keyboard commands while in SDL games. If you wish to turn it up to 11, you can disable keyboard grabbing at X11 level using {{AUR|libx11-nokeyboardgrab}}, or with more fine-grained control with {{AUR|libx11-ldpreloadnograb}} using the LD_PRELOAD environment variable to run applications with particular grab prevention. Wine/lib32 users should also look at the respective lib32 libraries.
  
 
{{Note | SDL is known to sometimes not be able to grab the input system. In such a case, it may succeed in grabbing it after a few seconds of waiting.}}
 
{{Note | SDL is known to sometimes not be able to grab the input system. In such a case, it may succeed in grabbing it after a few seconds of waiting.}}
  
 
=== Starting games in a separate X server ===
 
=== Starting games in a separate X server ===
In some cases like those mentioned above, it may be necessary or desired to run a second X server. Running a second X server has multiple advantages such as better performance, the ability to "tab" our of your game by using CTRL-ALT-F7 / CTRL-ALT-F8, no crashing your primary X session (which may have open work) in case a game conflicts with the graphics driver. To start a second X server (using [http://alientrap.org/nexuiz/ Nexuiz] as an example) you can simply do:  
+
In some cases like those mentioned above, it may be necessary or desired to run a second X server. Running a second X server has multiple advantages such as better performance, the ability to "tab" out of your game by using CTRL-ALT-F7 / CTRL-ALT-F8, no crashing your primary X session (which may have open work on) in case a game conflicts with the graphics driver. To start a second X server (using [http://alientrap.org/nexuiz/ Nexuiz] as an example) you can simply do:  
 
  xinit /usr/bin/nexuiz-glx -- :1
 
  xinit /usr/bin/nexuiz-glx -- :1
 
This can further be spiced up by using a seperate X configuration file:
 
This can further be spiced up by using a seperate X configuration file:
Line 90: Line 92:
 
For games that require exceptional amount of mouse skill, adjusting the response rate can help improve accuracy.  Read more [[Mouse_Polling_Rate|here]].
 
For games that require exceptional amount of mouse skill, adjusting the response rate can help improve accuracy.  Read more [[Mouse_Polling_Rate|here]].
  
== Performance on netbooks ==
+
=== HRTF filters with OpenAL ===
{{accuracy|Talk:Netbook Games}}
+
For games using OpenAL, if you use headphones you may get much better positional audio using OpenAL's HRTF filters. To enable, edit {{ic|/etc/openal/alsoft.conf}} (Or copy the example configuration file if it doesn't exist) and change:
 +
#hrtf = false
 +
to
 +
hrtf = true
 +
 
 +
=== Tuning Pulseaudio ===
 +
If you're using [[Pulseaudio]], you may wish to tweak some default settings to make sure it's running optimally.
 +
==== Enabling realtime priority and negative nice level ====
 +
Pulseaudio is built to be run with realtime priority, being an audio daemon. However, because of security risks of it locking up the system, it's scheduled as a regular thread by default. To adjust this, first make sure you're in the '''audio''' group. Then, uncomment and edit the following lines in {{ic|/etc/pulse/daemon.conf}}:
 +
high-priority = yes
 +
nice-level = -11
 +
 
 +
realtime-scheduling = yes
 +
realtime-priority = 5
 +
and restart pulseaudio.
 +
==== Using higher quality remixing for better sound ====
 +
Pulseaudio on Arch uses speex-float-0 by default to remix channels, which is considered a 'medium-low' quality remixing. If your system can handle the extra load, you may benefit from setting it to one of the following instead:
 +
resample-method = speex-float-10
 +
resample-method = src-sinc-best-quality
 +
==== Matching hardware buffers to Pulse's buffering ====
 +
Matching the buffers can reduce stuttering and increase performance marginally. See [http://forums.linuxmint.com/viewtopic.php?f=42&t=44862 here] for more details.
 +
 
 +
=== Cgroups ===
 +
 
 +
Cgroups are a kernel adjustment that allows processes to be grouped together and prioritized in userspace, allowing for minimum latency. They adjust several factors, such as IO prioritization and CPU prioritization.
 +
 
 +
==== Option 1 - Systemd (Recommended) ====
 +
 
 +
[[Systemd]] is able to handle Cgroups less specifically by itself, in order to make the system run smoothly with any number of threads running.
 +
 
 +
Simply install it to take advantage of this improvement.
 +
 
 +
==== Option 2 - Ulatencyd ====
 +
{{Note|Ulatencyd seems to sometimes over-prioritize, especially when it comes to block IO, which can often starve other threads from the same process or process group. [[Systemd]] provides a much more lightweight approach.}}
 +
 
 +
[[Ulatencyd]] is a daemon which uses dynamic cgroups to give the kernel hints to reduce latency in the system. It comes with a number of configs, and is extensively helpful in prioritizing disk I/O. Installing it will again increase responsiveness and reduce input lag. To use, simply install and add to your DAEMONS in rc.conf.
 +
 
 +
In addition, Ulatencyd has it's own method for specifically reducing latency in games, by focusing in on that one individual process. To take advantage of this, add entries into {{ic|/etc/ulatencyd/simple.d/games.conf}}:
 +
bit.trip.runner user.game
 +
hl2.exe        user.game
 +
/opt/cogs/*    user.game inherit=1
 +
 
 +
If you are using an SSD or simply have changed the default scheduler for any block devices, it may be advisable to edit the default settings, as [[Ulatencyd]] reverts the default scheduler back to cfq.
 +
 
 +
However, CFQ does seem to be best at load balancing when multiple threads are involved, which is a very common arrangement for games. It's best to try all available schedulers before settling on any particular one.
 +
 
 +
=== Double check your CPU frequency scaling settings ===
 +
 
 +
If your system is currently configured to properly insert its own cpu frequency scaling driver, the system sets the default governor to Ondemand. By default, this governor only adjusts the clock if the system is utilizing 95% of its CPU, and then only for a very short period of time. This saves power and reduces heat, but has a noticeable impact on performance. You can instead only have the system downclock when it is idle, by tuning the system governor. To do so, see [[Cpufrequtils#Improving_on-demand_performance]].
 +
 
 +
== Improving framerates and responsiveness with scheduling policies ==
 +
Most every game can benefit if given the correct scheduling policies for the kernel to prioritize the task. However, without the help of a daemon, this rescheduling would have to be carried out manually or through the use of several daemons for each policy. These policies should ideally be set per-thread by the application itself, but not all developers implement these policies. There are several methods for getting them to work anyway:
 +
 
 +
=== For Wine programs ===
 +
 
 +
{{AUR|wine-rt}} is a patched version of WINE that implements scheduling policies on a per-thread basis, using the equivalent of what the Windows developers had intended the threads to be run at. The default patch is more oriented towards professional audio users, and tends to be too heavy-handed of an approach for gaming. You may instead wish to use [http://pastebin.com/D9GBzBBv this patch], which also includes nice levels and uses more than one policy decision. Be warned that it uses SCHED_ISO, which is only properly implemented on [[Linux-ck]], and will simply renice THREAD_PRIORITY_ABOVE_NORMAL threads if your system does not support it.
 +
 +
=== For everything else ===
 +
 
 +
For programs which do not implement scheduling policies on their own, one tool known as '''schedtool''', and it's associated daemon '''schedtoold''' (available on the [https://aur.archlinux.org/packages.php?ID=5556 AUR]) can handle many of these tasks automatically.
 +
To edit what programs relieve what policies, simply edit /etc/schedtoold.conf and add the program followed by the schedtool arguments desired.
 +
 
 +
==== Policies ====
 +
First and foremost, setting the scheduling policy to SCHED_ISO will not only allow the process to use a maximum of 80 percent of the CPU, but will attempt to reduce latency and stuttering wherever possible.
 +
SCHED_ISO requires [[Linux-ck]] to operate, as it has only been implemented in that kernel. [[Linux-ck]] itself provides a hefty latency reduction, and should ideally be installed
 +
Most if not all games will benefit from this:
 +
bit.trip.runner -I
 +
For users not using [[Linux-ck]], SCHED_FIFO provides an alternative, that can even work better. You should test to see if your applications run more smoothly with SCHED_FIFO, in which case by all means use it instead. Be warned though, as SCHED_FIFO runs the risk of starving the system! Use this in cases where -I is used below:
 +
bit.trip.runner -F -p 15
 +
 
 +
==== Nice levels ====
 +
Secondly, the nice level sets which tasks are processed first, in ascending order. A nice level of -4 is reccommended for most multimedia tasks, including games:
 +
bit.trip.runner -n -4
 +
 
 +
==== Core affinity ====
 +
There is some confusion in development as to whether the driver should be multithreading, or the program. In any case where they both attempt it, it causes drops in framerate and crashes. Examples of this include a number of modern games, and any WINE program which is running without GLSL disabled. To select a single core and allow only the driver to handle this process, simply use the -a 0x# flag:
 +
bit.trip.runner -a 0x1 #Use cores 1
 +
Some CPUs are hyperthreaded and have only 2 or 4 cores but show up as 4 or 8, and are best accounted for:
 +
bit.trip.runner -a 0x5 #Use virtual cores 0101, or 1 and 3
 +
 
 +
==== General case ====
 +
For most games which require high framerates and low latency, usage of all of these flags seems to work best. Affinity should be checked per-program, however, as most native games can understand the correct usage.
 +
For a general case:
 +
bit.trip.runner -I -n -4
 +
Amnesia.bin64 -I -n -4
 +
hl2.exe -I -n -4 -a 0x1 #Wine with GLSL enabled
 +
etc, etc.
 +
 
 +
==== Optimus, and other helping programs ====
 +
As a general rule, any other process which the game requires to operate should be reniced to a level above that of the game itself. Strangely, Wine has a problem known as 'reverse scheduling', it can often have benefits when the more important processes are set to a higher nice level. Wineserver also seems unconditionally to benefit from SCHED_FIFO, since rarely consumes the whole CPU and needs higher prioritization when possible.
 +
optirun -I -n -5
 +
wineserver -F -p 20 -n 19
 +
steam.exe -I -n -5
 +
 
 +
== Using alternate kernels ==
 +
 
 +
The stock ARCH kernel provides a very good baseline for general usage. However, if your system has less than 16 cores and is intended for use primarily as a workstation, you can sacrifice a small amount of throughput on batch workloads and gain a significant boost to interactivity by using [[Linux-ck]]. If you prefer not to compile your own kernel, you can instead add [[Repo-ck]] and use one of their kernels. Using a pre-optimized kernel will most definitely offset any loss of throughput that may have occurred as a result, so be sure to select the appropriate kernel for your architecture.
 +
 
 +
=== Using BFQ ===
  
Most games will benefit from a RAM upgrade, especially to 2GB (the max supported in most current netbooks). They will often also benefit from overclocking the Intel Atom processor, especially a 24% overclock, that is possible with a bios upgrade in the MSI Wind U100, and possibly others.
+
BFQ is an io-scheduler that comes as a feature of [[Linux-ck]], and is optimized to be much more simplistic, but provides better interactivity and throughput for non-server workloads. To enable, see [[Linux-ck#How_to_Enable_the_BFQ_I.2FO_Scheduler]]. It is important to note that although most guides recommend using either '''noop''' or '''deadline''' for SSDs for their raw throughput, they are actually detrimental to interactivity when more than one thread is attempting to access the device. It's best to use '''bfq''' unless you desperately need the throughput advantage.
  
 
== See also ==
 
== See also ==
* [http://www.freegamer.blogspot.com/ Free Games] - Excellent blog about FOSS games
 
 
* [http://www.linuxgames.com/ LinuxGames] - News on linux games
 
* [http://www.linuxgames.com/ LinuxGames] - News on linux games
 
* [http://freegamer.blogspot.com/ Free Gamer] - Open source games blog
 
* [http://freegamer.blogspot.com/ Free Gamer] - Open source games blog
 
* [http://forum.freegamedev.net/ FreeGameDev] - Free/open source game development community
 
* [http://forum.freegamedev.net/ FreeGameDev] - Free/open source game development community
* [http://libregamewiki.org/ Libregamewiki] - Free software games wiki
 
 
* [https://fedoraproject.org/wiki/SIGs/Games#Gaming_News_sites SIG/Games] - OS/Linux gaming news sites and lists at Fedora's wiki
 
* [https://fedoraproject.org/wiki/SIGs/Games#Gaming_News_sites SIG/Games] - OS/Linux gaming news sites and lists at Fedora's wiki
 
* [http://live.linux-gamers.net live.linux-gamers] - Arch-based live gaming distro
 
* [http://live.linux-gamers.net live.linux-gamers] - Arch-based live gaming distro
 +
* [http://www.gamesonlinux.com Games on Linux] - Commercial Games On Linux
 +
* [http://www.gamingonlinux.com/ Gaming on Linux] - An active Linux gaming news and editorial source and community

Revision as of 15:52, 11 June 2013

Template:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary wiki Template:Article summary wiki Template:Article summary wiki Template:Article summary wiki Template:Article summary end

This page only contains information about running games and related system configuration tips. For lists of popular games for GNU/Linux see List of Applications/Games and Netbook Games.

Game Environments

Different environments exist to play games in Linux:

  • Native – Games written for Linux (usually Free & Open Source).
  • Browser – you need only browser and Internet connection to play these types of games.
    • Plugin-based – you need to install plugin to play.
      • Java Webstart – used to install cross-platform games very easily.
      • Flash games are very common on the Web.
      • Unity – specialized game plugin for browsers. Currently works only in Google Chrome. Most games are commercial and/or closed-source.
    • HTML 5 games use brand new canvas and WebGL technologies and work in all modern browsers but can be very slow on weak machines.
  • Specialized environments (software emulators) – – Required for running software designed for other architectures or systems (Heed the copyright laws of your country!)
    • Wine – allows running of some Windows games, as well as a large amount of Windows software.
    • Crossover Games – members of the Codeweavers team are prime supporters of Wine. Using Crossover Games makes the installation & setting up of some games easier, more reliable & even possible, when compared to using other methods. Crossover is a paid commercial product, which also provides a forum where the developers are very much involved in the community.
    • Cedega – game-oriented Wine derivative. Its packaged version is not free of charge unlike its CVS version.
    • DosBox – DOS emulator
    • scummvm – emulates games based on the SCUMM game engine, which ran many classic adventure games.
  • Hardware emulators – emulate the whole device instead of software environment. The same thing about Copyright here.

Getting games

Native

A good number are available in the Official repositories or in the AUR. Loki provides installers for several games. Desura can be considered good source of games (if you don't care about security and bugs too much).

Wine

  • Centralized source of information about running games (and other applications) in Wine is Wine AppDB.
  • See also Category:Wine.

Flash

Several huge flash games portals exists, among them are:

Java

Running games in Arch

Certain games or game types may need special configuration to run or to run as expected. For the most part, games will work right out of the box in Arch Linux with possibly better performance than on other distributions due to compile time optimizations. However, some special setups may require a bit of configuration or scripting to make games run as smoothly as desired.

Multi-screen setups

Running a multi-screen setup may lead to problems with fullscreen games. In such a case, running a second X server is one possible solution. Another solution may be found in the NVIDIA article (may also apply to non-NVIDIA users).

Keyboard Grabbing

Many games grab the keyboard, noticeably preventing you from switching windows (also known as alt-tabbing). Download sdl-nokeyboardgrabAUR to gain the ability to use keyboard commands while in SDL games. If you wish to turn it up to 11, you can disable keyboard grabbing at X11 level using libx11-nokeyboardgrabAUR, or with more fine-grained control with libx11-ldpreloadnograbAUR using the LD_PRELOAD environment variable to run applications with particular grab prevention. Wine/lib32 users should also look at the respective lib32 libraries.

Note: SDL is known to sometimes not be able to grab the input system. In such a case, it may succeed in grabbing it after a few seconds of waiting.

Starting games in a separate X server

In some cases like those mentioned above, it may be necessary or desired to run a second X server. Running a second X server has multiple advantages such as better performance, the ability to "tab" out of your game by using CTRL-ALT-F7 / CTRL-ALT-F8, no crashing your primary X session (which may have open work on) in case a game conflicts with the graphics driver. To start a second X server (using Nexuiz as an example) you can simply do:

xinit /usr/bin/nexuiz-glx -- :1

This can further be spiced up by using a seperate X configuration file:

xinit /usr/bin/nexuiz-glx -- :1 -xf86config xorg-game.conf 

A good reason to provide an alternative xorg.conf here may be that your primary configuration makes use of NVIDIA's Twinview which would render your 3D games like Nexuiz in the middle of your multiscreen setup, spanned across all screens. This is undesirable, thus starting a second X with an alternative config where the second screen is disabled is advised.

A game starting script making use of Openbox for your home directory or /usr/local/bin may look like this:

$ cat ~/game.sh
if [ $# -ge 1 ]; then
  game="`which $1`"
  openbox="`which openbox`"
  tmpgame="/tmp/tmpgame.sh"
  DISPLAY=:1.0
  echo -e "${openbox} &\n${game}" > ${tmpgame}
  echo "starting ${game}"
  xinit ${tmpgame} -- :1 -xf86config xorg-game.conf || exit 1
else
  echo "not a valid argument"
fi

So after a chmod +x you would be able to use this script like:

$ ~/game.sh nexuiz-glx

Adjusting mouse detections

For games that require exceptional amount of mouse skill, adjusting the response rate can help improve accuracy. Read more here.

HRTF filters with OpenAL

For games using OpenAL, if you use headphones you may get much better positional audio using OpenAL's HRTF filters. To enable, edit /etc/openal/alsoft.conf (Or copy the example configuration file if it doesn't exist) and change:

#hrtf = false

to

hrtf = true

Tuning Pulseaudio

If you're using Pulseaudio, you may wish to tweak some default settings to make sure it's running optimally.

Enabling realtime priority and negative nice level

Pulseaudio is built to be run with realtime priority, being an audio daemon. However, because of security risks of it locking up the system, it's scheduled as a regular thread by default. To adjust this, first make sure you're in the audio group. Then, uncomment and edit the following lines in /etc/pulse/daemon.conf:

high-priority = yes
nice-level = -11
realtime-scheduling = yes
realtime-priority = 5

and restart pulseaudio.

Using higher quality remixing for better sound

Pulseaudio on Arch uses speex-float-0 by default to remix channels, which is considered a 'medium-low' quality remixing. If your system can handle the extra load, you may benefit from setting it to one of the following instead:

resample-method = speex-float-10
resample-method = src-sinc-best-quality

Matching hardware buffers to Pulse's buffering

Matching the buffers can reduce stuttering and increase performance marginally. See here for more details.

Cgroups

Cgroups are a kernel adjustment that allows processes to be grouped together and prioritized in userspace, allowing for minimum latency. They adjust several factors, such as IO prioritization and CPU prioritization.

Option 1 - Systemd (Recommended)

Systemd is able to handle Cgroups less specifically by itself, in order to make the system run smoothly with any number of threads running.

Simply install it to take advantage of this improvement.

Option 2 - Ulatencyd

Note: Ulatencyd seems to sometimes over-prioritize, especially when it comes to block IO, which can often starve other threads from the same process or process group. Systemd provides a much more lightweight approach.

Ulatencyd is a daemon which uses dynamic cgroups to give the kernel hints to reduce latency in the system. It comes with a number of configs, and is extensively helpful in prioritizing disk I/O. Installing it will again increase responsiveness and reduce input lag. To use, simply install and add to your DAEMONS in rc.conf.

In addition, Ulatencyd has it's own method for specifically reducing latency in games, by focusing in on that one individual process. To take advantage of this, add entries into /etc/ulatencyd/simple.d/games.conf:

bit.trip.runner user.game
hl2.exe         user.game
/opt/cogs/*     user.game inherit=1

If you are using an SSD or simply have changed the default scheduler for any block devices, it may be advisable to edit the default settings, as Ulatencyd reverts the default scheduler back to cfq.

However, CFQ does seem to be best at load balancing when multiple threads are involved, which is a very common arrangement for games. It's best to try all available schedulers before settling on any particular one.

Double check your CPU frequency scaling settings

If your system is currently configured to properly insert its own cpu frequency scaling driver, the system sets the default governor to Ondemand. By default, this governor only adjusts the clock if the system is utilizing 95% of its CPU, and then only for a very short period of time. This saves power and reduces heat, but has a noticeable impact on performance. You can instead only have the system downclock when it is idle, by tuning the system governor. To do so, see Cpufrequtils#Improving_on-demand_performance.

Improving framerates and responsiveness with scheduling policies

Most every game can benefit if given the correct scheduling policies for the kernel to prioritize the task. However, without the help of a daemon, this rescheduling would have to be carried out manually or through the use of several daemons for each policy. These policies should ideally be set per-thread by the application itself, but not all developers implement these policies. There are several methods for getting them to work anyway:

For Wine programs

wine-rtAUR is a patched version of WINE that implements scheduling policies on a per-thread basis, using the equivalent of what the Windows developers had intended the threads to be run at. The default patch is more oriented towards professional audio users, and tends to be too heavy-handed of an approach for gaming. You may instead wish to use this patch, which also includes nice levels and uses more than one policy decision. Be warned that it uses SCHED_ISO, which is only properly implemented on Linux-ck, and will simply renice THREAD_PRIORITY_ABOVE_NORMAL threads if your system does not support it.

For everything else

For programs which do not implement scheduling policies on their own, one tool known as schedtool, and it's associated daemon schedtoold (available on the AUR) can handle many of these tasks automatically. To edit what programs relieve what policies, simply edit /etc/schedtoold.conf and add the program followed by the schedtool arguments desired.

Policies

First and foremost, setting the scheduling policy to SCHED_ISO will not only allow the process to use a maximum of 80 percent of the CPU, but will attempt to reduce latency and stuttering wherever possible. SCHED_ISO requires Linux-ck to operate, as it has only been implemented in that kernel. Linux-ck itself provides a hefty latency reduction, and should ideally be installed Most if not all games will benefit from this:

bit.trip.runner -I

For users not using Linux-ck, SCHED_FIFO provides an alternative, that can even work better. You should test to see if your applications run more smoothly with SCHED_FIFO, in which case by all means use it instead. Be warned though, as SCHED_FIFO runs the risk of starving the system! Use this in cases where -I is used below:

bit.trip.runner -F -p 15

Nice levels

Secondly, the nice level sets which tasks are processed first, in ascending order. A nice level of -4 is reccommended for most multimedia tasks, including games:

bit.trip.runner -n -4

Core affinity

There is some confusion in development as to whether the driver should be multithreading, or the program. In any case where they both attempt it, it causes drops in framerate and crashes. Examples of this include a number of modern games, and any WINE program which is running without GLSL disabled. To select a single core and allow only the driver to handle this process, simply use the -a 0x# flag:

bit.trip.runner -a 0x1 #Use cores 1

Some CPUs are hyperthreaded and have only 2 or 4 cores but show up as 4 or 8, and are best accounted for:

bit.trip.runner -a 0x5 #Use virtual cores 0101, or 1 and 3

General case

For most games which require high framerates and low latency, usage of all of these flags seems to work best. Affinity should be checked per-program, however, as most native games can understand the correct usage. For a general case:

bit.trip.runner -I -n -4
Amnesia.bin64 -I -n -4
hl2.exe -I -n -4 -a 0x1 #Wine with GLSL enabled

etc, etc.

Optimus, and other helping programs

As a general rule, any other process which the game requires to operate should be reniced to a level above that of the game itself. Strangely, Wine has a problem known as 'reverse scheduling', it can often have benefits when the more important processes are set to a higher nice level. Wineserver also seems unconditionally to benefit from SCHED_FIFO, since rarely consumes the whole CPU and needs higher prioritization when possible.

optirun -I -n -5
wineserver -F -p 20 -n 19
steam.exe -I -n -5

Using alternate kernels

The stock ARCH kernel provides a very good baseline for general usage. However, if your system has less than 16 cores and is intended for use primarily as a workstation, you can sacrifice a small amount of throughput on batch workloads and gain a significant boost to interactivity by using Linux-ck. If you prefer not to compile your own kernel, you can instead add Repo-ck and use one of their kernels. Using a pre-optimized kernel will most definitely offset any loss of throughput that may have occurred as a result, so be sure to select the appropriate kernel for your architecture.

Using BFQ

BFQ is an io-scheduler that comes as a feature of Linux-ck, and is optimized to be much more simplistic, but provides better interactivity and throughput for non-server workloads. To enable, see Linux-ck#How_to_Enable_the_BFQ_I.2FO_Scheduler. It is important to note that although most guides recommend using either noop or deadline for SSDs for their raw throughput, they are actually detrimental to interactivity when more than one thread is attempting to access the device. It's best to use bfq unless you desperately need the throughput advantage.

See also