linux-kernel - Re: [PATCH] sched/fair: sync expires_seq in distribute_cfs

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Message-ID: <CAM_iQpUA8mn_kTGsJJDKBH0gF1tErg3RnuG0bYd6amH2T_YLHw@mail.gmail.com>
Date:   Fri, 3 Aug 2018 14:56:03 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Ben Segall <bsegall@...gle.com>
Cc:     Xunlei Pang <xlpang@...ux.alibaba.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] sched/fair: sync expires_seq in distribute_cfs_runtime()

On Wed, Aug 1, 2018 at 10:17 AM <bsegall@...gle.com> wrote:
> Yes, in practice what's actually going to happen is that the
> runtime_remaining will be put to 1 by distribute, the cfs_rq will be
> unthrottled, and then when it runs it will go negative immediately and
> hit the negative check in expires, so expires_seq being wrong will not
> actually matter. In addition, the worst thing that will happen if one of
> the account_cfs_rq_runtime(cfs_rq, 0) paths is hit first is that it will
> lose 1ns of quota, which also doesn't really matter.

Ah, I see.

Thanks!