On 21/08/14 14:46, Ingo Molnar wrote: > * Juri Lelli <juri.lelli@xxxxxxx> wrote: > >> Section 4 intro was still describing the old interface. Rewrite it. >> >> Signed-off-by: Juri Lelli <juri.lelli@xxxxxxx> >> Signed-off-by: Luca Abeni <luca.abeni@xxxxxxxx> >> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> >> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> >> Cc: Ingo Molnar <mingo@xxxxxxxxxx> >> Cc: Henrik Austad <henrik@xxxxxxxxx> >> Cc: Dario Faggioli <raistlin@xxxxxxxx> >> Cc: Juri Lelli <juri.lelli@xxxxxxxxx> >> Cc: linux-doc@xxxxxxxxxxxxxxx >> Cc: linux-kernel@xxxxxxxxxxxxxxx >> --- >> Documentation/scheduler/sched-deadline.txt | 49 +++++++++++++++--------------- >> 1 file changed, 24 insertions(+), 25 deletions(-) >> >> diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt >> index dce6d63..8372c3d 100644 >> --- a/Documentation/scheduler/sched-deadline.txt >> +++ b/Documentation/scheduler/sched-deadline.txt >> @@ -165,39 +165,38 @@ CONTENTS >> >> In order for the -deadline scheduling to be effective and useful, it is >> important to have some method to keep the allocation of the available CPU >> - bandwidth to the tasks under control. >> - This is usually called "admission control" and if it is not performed at all, >> - no guarantee can be given on the actual scheduling of the -deadline tasks. >> - >> - Since when RT-throttling has been introduced each task group has a bandwidth >> - associated, calculated as a certain amount of runtime over a period. >> - Moreover, to make it possible to manipulate such bandwidth, readable/writable >> - controls have been added to both procfs (for system wide settings) and cgroupfs >> - (for per-group settings). >> - Therefore, the same interface is being used for controlling the bandwidth >> - distrubution to -deadline tasks. >> - >> - However, more discussion is needed in order to figure out how we want to manage >> - SCHED_DEADLINE bandwidth at the task group level. Therefore, SCHED_DEADLINE >> - uses (for now) a less sophisticated, but actually very sensible, mechanism to >> - ensure that a certain utilization cap is not overcome per each root_domain. >> - >> - Another main difference between deadline bandwidth management and RT-throttling >> + bandwidth to the tasks under control. This is usually called "admission >> + control" and if it is not performed at all, no guarantee can be given on >> + the actual scheduling of the -deadline tasks. >> + >> + The interface used to control the fraction of CPU bandwidth that can be >> + allocated to -deadline tasks is similar to the one already used for -rt >> + tasks with real-time group scheduling (a.k.a. RT-throttling - see >> + Documentation/scheduler/sched-rt-group.txt), and is based on readable/ >> + writable control files located in procfs (for system wide settings). >> + Notice that per-group settings (controlled through cgroupfs) are still not >> + defined for -deadline tasks, because more discussion is needed in order to >> + figure out how we want to manage SCHED_DEADLINE bandwidth at the task group >> + level. >> + >> + A main difference between deadline bandwidth management and RT-throttling >> is that -deadline tasks have bandwidth on their own (while -rt ones don't!), >> and thus we don't need an higher level throttling mechanism to enforce the > > s/an higher/a higher > >> - desired bandwidth. >> + desired bandwidth. Therefore, using this simple interface, we can put a cap > > s/interface, we/interface we > >> + on total utilization of -deadline tasks (i.e., \Sum (runtime_i / period_i) < >> + some_desired_value). > Fixed. Thanks a lot, - Juri -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
