Messages in this thread Patch in this message | | | From | Honglei Wang <> | Subject | [PATCH v2 3/3] sched/fair: update burst feature description | Date | Wed, 8 Dec 2021 22:52:23 +0800 |
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Update the burst feature description due to the burst periods limit.
Signed-off-by: Honglei Wang <wanghonglei@didichuxing.com> --- Documentation/scheduler/sched-bwc.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/Documentation/scheduler/sched-bwc.rst b/Documentation/scheduler/sched-bwc.rst index 173c14110c85..eac39d42ebf9 100644 --- a/Documentation/scheduler/sched-bwc.rst +++ b/Documentation/scheduler/sched-bwc.rst @@ -65,6 +65,18 @@ there many cgroups or CPU is under utilized, the interference is limited. More details are shown in: https://lore.kernel.org/lkml/5371BD36-55AE-4F71-B9D7-B86DC32E3D2B@linux.alibaba.com/ +We need to limit the burst periods to 2, because we found something interesting +that with the feature, tasks have chance to get more cpu than quota in working +periods. As every task could be scheduled out or sleep, the task group can get +some more cpu for its burst workload in this way. But even if there's no burst +workload, it can use those power to do daily jobs. If the average workload of a +taskgroup is just a little bit higher than its quota, it can escape from the +throttle and using the burst power for lots of periods. + +Permitting 2 periods for the burst cpu can help aovid such kind of 'stealing' +and the task group won't lose its burst power if the periods refresh lands in +the middle of a burst workloads. + Management ---------- Quota, period and burst are managed within the cpu subsystem via cgroupfs. -- 2.14.1
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