From: Peter Zijlstra <peterz@infradead.org>
To: Huaixin Chang <changhuaixin@linux.alibaba.com>
Cc: bsegall@google.com, dietmar.eggemann@arm.com,
juri.lelli@redhat.com, khlebnikov@yandex-team.ru,
linux-kernel@vger.kernel.org, mgorman@suse.de, mingo@redhat.com,
odin@uged.al, odin@ugedal.com, pauld@redhead.com, pjt@google.com,
rostedt@goodmis.org, shanpeic@linux.alibaba.com, tj@kernel.org,
vincent.guittot@linaro.org, xiyou.wangcong@gmail.com
Subject: Re: [PATCH v4 1/4] sched/fair: Introduce primitives for CFS bandwidth burst
Date: Tue, 16 Mar 2021 10:54:37 +0100 [thread overview]
Message-ID: <YFCAXeZj6sXBI5Ls@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210316044931.39733-2-changhuaixin@linux.alibaba.com>
On Tue, Mar 16, 2021 at 12:49:28PM +0800, Huaixin Chang wrote:
> @@ -8982,6 +8983,12 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
> if (quota != RUNTIME_INF && quota > max_cfs_runtime)
> return -EINVAL;
>
> + /*
> + * Bound burst to defend burst against overflow during bandwidth shift.
> + */
> + if (burst > max_cfs_runtime)
> + return -EINVAL;
Why do you allow such a large burst? I would expect something like:
if (burst > quote)
return -EINVAL;
That limits the variance in the system. Allowing super long bursts seems
to defeat the entire purpose of bandwidth control.
next prev parent reply other threads:[~2021-03-16 9:56 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 4:49 [PATCH v4 0/4] sched/fair: Burstable CFS bandwidth controller Huaixin Chang
2021-03-16 4:49 ` [PATCH v4 1/4] sched/fair: Introduce primitives for CFS bandwidth burst Huaixin Chang
2021-03-16 9:27 ` Peter Zijlstra
2021-03-16 9:41 ` Peter Zijlstra
2021-03-16 9:54 ` Peter Zijlstra [this message]
2021-03-17 7:16 ` changhuaixin
2021-03-17 8:06 ` Peter Zijlstra
2021-03-18 1:26 ` changhuaixin
2021-03-18 12:59 ` Phil Auld
2021-03-18 15:10 ` Peter Zijlstra
2021-04-19 8:18 ` changhuaixin
2021-03-19 12:51 ` changhuaixin
2021-03-18 15:05 ` Peter Zijlstra
2021-03-19 12:39 ` changhuaixin
2021-03-20 2:06 ` changhuaixin
2021-05-12 12:41 ` changhuaixin
2021-03-16 10:40 ` Peter Zijlstra
2021-03-16 4:49 ` [PATCH v4 2/4] sched/fair: Make CFS bandwidth controller burstable Huaixin Chang
2021-03-16 9:52 ` Peter Zijlstra
2021-03-16 4:49 ` [PATCH v4 3/4] sched/fair: Add cfs bandwidth burst statistics Huaixin Chang
2021-03-16 4:49 ` [PATCH v4 4/4] sched/fair: Add document for burstable CFS bandwidth control Huaixin Chang
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