diff options
| author | J. Bruce Fields <bfields@citi.umich.edu> | 2008-04-07 16:39:38 -0400 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2008-04-11 13:21:03 -0600 |
| commit | d396c5f158547e50c2b78bc984cb4a72d76e969b (patch) | |
| tree | 78c971a29d215d0102252ddc014f5e3ee2415a5d /Documentation/sched-rt-group.txt | |
| parent | 8bcd1cc293f4e76edbfd8f422770c80a018b82d9 (diff) | |
| download | kernel-crypto-d396c5f158547e50c2b78bc984cb4a72d76e969b.tar.gz kernel-crypto-d396c5f158547e50c2b78bc984cb4a72d76e969b.tar.xz kernel-crypto-d396c5f158547e50c2b78bc984cb4a72d76e969b.zip | |
Move sched-rt-group.txt to scheduler/
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/sched-rt-group.txt')
| -rw-r--r-- | Documentation/sched-rt-group.txt | 59 |
1 files changed, 0 insertions, 59 deletions
diff --git a/Documentation/sched-rt-group.txt b/Documentation/sched-rt-group.txt deleted file mode 100644 index 1c6332f4543..00000000000 --- a/Documentation/sched-rt-group.txt +++ /dev/null @@ -1,59 +0,0 @@ - - -Real-Time group scheduling. - -The problem space: - -In order to schedule multiple groups of realtime tasks each group must -be assigned a fixed portion of the CPU time available. Without a minimum -guarantee a realtime group can obviously fall short. A fuzzy upper limit -is of no use since it cannot be relied upon. Which leaves us with just -the single fixed portion. - -CPU time is divided by means of specifying how much time can be spent -running in a given period. Say a frame fixed realtime renderer must -deliver 25 frames a second, which yields a period of 0.04s. Now say -it will also have to play some music and respond to input, leaving it -with around 80% for the graphics. We can then give this group a runtime -of 0.8 * 0.04s = 0.032s. - -This way the graphics group will have a 0.04s period with a 0.032s runtime -limit. - -Now if the audio thread needs to refill the DMA buffer every 0.005s, but -needs only about 3% CPU time to do so, it can do with a 0.03 * 0.005s -= 0.00015s. - - -The Interface: - -system wide: - -/proc/sys/kernel/sched_rt_period_ms -/proc/sys/kernel/sched_rt_runtime_us - -CONFIG_FAIR_USER_SCHED - -/sys/kernel/uids/<uid>/cpu_rt_runtime_us - -or - -CONFIG_FAIR_CGROUP_SCHED - -/cgroup/<cgroup>/cpu.rt_runtime_us - -[ time is specified in us because the interface is s32; this gives an - operating range of ~35m to 1us ] - -The period takes values in [ 1, INT_MAX ], runtime in [ -1, INT_MAX - 1 ]. - -A runtime of -1 specifies runtime == period, ie. no limit. - -New groups get the period from /proc/sys/kernel/sched_rt_period_us and -a runtime of 0. - -Settings are constrained to: - - \Sum_{i} runtime_{i} / global_period <= global_runtime / global_period - -in order to keep the configuration schedulable. |