User:Unikum/Ulatencyd

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Revision as of 09:28, 24 January 2013 by Halosghost (Talk | contribs) (Updated to reflect shift to systemd)

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Ulatency is a daemon that controls how the Linux kernel will spend it's resources on the running processes. It uses dynamic cgroups to give the kernel hints and limitations on processes.

It strongly supports the lua scripting language for writing rules and the scheduler code.

Installation

Kernel options requires:

PROC_EVENTS=y
CONFIG_CGROUPS=y
CONFIG_CGROUP_FREEZER=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CGROUP_MEM_RES_CTLR=y
CONFIG_CGROUP_MEM_RES_CTLR_SWAP=y
CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED=y
CONFIG_CGROUP_SCHED=y
CONFIG_FAIR_GROUP_SCHED=y
CONFIG_RT_GROUP_SCHED=y
CONFIG_BLK_CGROUP=y
CONFIG_CFQ_GROUP_IOSCHED=y

Install ulatencydAUR from the AUR or the ArchAudio/testing repository.

You may wish to get the latest fixes and rules from Git with ulatencyd-gitAUR.

There are some important fixes that haven't yet been merged for kernels > 3.2.0, for blkio weight:

# curl https://raw.github.com/poelzi/ulatencyd/157bb03ee39024f49416c12ae727b171f2011233/conf/scheduler/20-desktop.lua > /etc/ulatencyd/scheduler/20-desktop.lua
# curl https://raw.github.com/poelzi/ulatencyd/157bb03ee39024f49416c12ae727b171f2011233/conf/scheduler/30-game.lua > /etc/ulatencyd/scheduler/30-game.lua
# curl https://raw.github.com/poelzi/ulatencyd/157bb03ee39024f49416c12ae727b171f2011233/conf/scheduler/30-single-task.lua > /etc/ulatencyd/scheduler/30-single-task.lua

To start ulatencyd:

# systemctl start ulatencyd.service

If you want ulatencyd start on boot, enable the service file as follows:

# systemctl enable ulatencyd.service

To verify that it works:

$  ulatency tree
 /sys/fs/cgroup/cpu
 └─┬»cpu«
   ├ 2 kthreadd
   ├─┬»s_ul«
   │ └ 4975 ulatencyd
   ├─┬»sys_bg«
   │ └ 1928 cron
   ├─┬»sys_idle«
   │ └ 3036 preload
   ...

Configuration

Some settings are adjustable in /etc/ulatencyd/ulatencyd.conf and the cgroups that will be used can be changed in /etc/ulatencyd/cgroups.conf

Ulatencyd by default changes the io scheduler for all devices to cfq, to disable this behavior (for if you configure your schedulers yourself), simply edit /etc/ulatencyd/rules/io.lua and comment out the lines:

   if self.first_run == true then
     self:set_scheduler(dev, ulatency.get_config("io", "scheduler") or "cfq")
   end

See also