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    SubjectRe: [PATCH] sched/fair: limit burst to zero when cfs bandwidth is toggled off
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    在 2022/9/30 16:32, zhaowenhui (A) 写道:
    >
    >
    > 在 2022/8/30 11:19, zhaowenhui (A) 写道:
    >>
    >>
    >> 在 2022/8/9 20:03, Zhao Wenhui 写道:
    >>> 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
    >>
    >> Gentle ping.
    >>
    >> Thanks,
    >> Zhao Wenhui
    >
    > Dear Maintainers,
    > Hi, this patch has been reviewed by two reviewers over a month ago.
    > So, Any more suggestions for this patch or it can be picked?
    >
    > Regards,
    > Zhao Wenhui

    Peter,
    Sorry to disturbed, for this patch is submitted long long time ago...
    And this is my first patch, so I really wonder if there is something
    to be improved for the patch.

    Looking forward to your reply.

    Thank you,
    Zhao Wenhui

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