Messages in this thread Patch in this message | | | From | Zhao Wenhui <> | Subject | [PATCH] sched/fair: limit burst to zero when cfs bandwidth is toggled off | Date | Tue, 9 Aug 2022 20:03:20 +0800 |
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When the quota value in CFS bandwidth is set to -1, that imples the cfs bandwidth is toggled off. So the burst feature is supposed to be disable as well.
Currently, when quota is -1, burst will not be check, so that it can be set to almost arbitery value. Examples: mkdir /sys/fs/cgroup/cpu/test echo -1 > /sys/fs/cgroup/cpu/test/cpu.cfs_quota_us echo 10000000000000000 > /sys/fs/cgroup/cpu/test/cpu.cfs_burst_us
Moreover, after the burst modified by this way, quota can't be set to any value: echo 100000 > cpu.cfs_quota_us -bash: echo: write error: Invalid argument
This patch can ensure the burst value being zero and unalterable, when quota is set to -1.
Fixes: f4183717b370 ("sched/fair: Introduce the burstable CFS controller") Reported-by: Zhao Gongyi <zhaogongyi@huawei.com> Signed-off-by: Zhao Wenhui <zhaowenhui8@huawei.com> --- kernel/sched/core.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ee28253c9ac0..4c1fc01d8c68 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -10584,6 +10584,12 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota, burst + quota > max_cfs_runtime)) return -EINVAL; + /* + * Ensure burst equals to zero when quota is -1. + */ + if (quota == RUNTIME_INF && burst) + return -EINVAL; + /* * Prevent race between setting of cfs_rq->runtime_enabled and * unthrottle_offline_cfs_rqs(). @@ -10643,8 +10649,10 @@ static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) period = ktime_to_ns(tg->cfs_bandwidth.period); burst = tg->cfs_bandwidth.burst; - if (cfs_quota_us < 0) + if (cfs_quota_us < 0) { quota = RUNTIME_INF; + burst = 0; + } else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC) quota = (u64)cfs_quota_us * NSEC_PER_USEC; else -- 2.17.1
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