Messages in this thread | | | Subject | Re: [PATCH 2/2] sched/fair: Advance global expiration when period timer is restarted | From | Xunlei Pang <> | Date | Tue, 19 Jun 2018 13:46:31 +0800 |
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On 6/19/18 12:36 PM, Cong Wang wrote: > On Mon, Jun 18, 2018 at 2:16 AM, Xunlei Pang <xlpang@linux.alibaba.com> wrote: >> I noticed the group frequently got throttled even it consumed >> low cpu usage, this caused some jitters on the response time >> to some of our business containers enabling cpu quota. >> >> It's very easy to reproduce: >> mkdir /sys/fs/cgroup/cpu/test >> cd /sys/fs/cgroup/cpu/test >> echo 100000 > cpu.cfs_quota_us >> echo $$ > tasks >> then repeat: >> cat cpu.stat |grep nr_throttled // nr_throttled will increase >> >> After some analysis, we found that cfs_rq::runtime_remaining will >> be cleared by expire_cfs_rq_runtime() due to two equal but stale >> "cfs_{b|q}->runtime_expires" after period timer is re-armed. >> >> The global expiration should be advanced accordingly when the >> bandwidth period timer is restarted. >> > > I observed the same problem and already sent some patches: > > https://lkml.org/lkml/2018/5/22/37 > https://lkml.org/lkml/2018/5/22/38 > https://lkml.org/lkml/2018/5/22/35 >
Looks they are related to large slice setting and unused slack under large number of cpus, the issue I described is a little different.
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