From: Peter Zijlstra <peterz@infradead.org>
To: Abel Wu <wuyun.abel@bytedance.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Barry Song <21cnbao@gmail.com>,
Benjamin Segall <bsegall@google.com>,
Chen Yu <yu.c.chen@intel.com>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
"Gautham R . Shenoy" <gautham.shenoy@amd.com>,
Joel Fernandes <joel@joelfernandes.org>,
K Prateek Nayak <kprateek.nayak@amd.com>,
Mike Galbraith <efault@gmx.de>, Qais Yousef <qyousef@layalina.io>,
Tim Chen <tim.c.chen@linux.intel.com>,
Yicong Yang <yangyicong@huawei.com>,
Youssef Esmat <youssefesmat@chromium.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] sched/eevdf: Fix vruntime adjustment on reweight
Date: Tue, 7 Nov 2023 10:52:31 +0100 [thread overview]
Message-ID: <20231107095231.GS8262@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20231107090510.71322-2-wuyun.abel@bytedance.com>
On Tue, Nov 07, 2023 at 05:05:07PM +0800, Abel Wu wrote:
> vruntime of the (on_rq && !0-lag) entity needs to be adjusted when
> it gets re-weighted, and the calculations can be simplified based
> on the fact that re-weight won't change the w-average of all the
> entities. Please check the proofs in comments.
>
> But adjusting vruntime can also cause position change in RB-tree
> hence require re-queue to fix up which might be costly. This might
> be avoided by deferring adjustment to the time the entity actually
> leaves tree (dequeue/pick), but that will negatively affect task
> selection and probably not good enough either.
>
> Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy")
> Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Very good, thanks!
It's a bit sad we have to muck about with the tree now, but alas.
If only Google and FB could agree on what to do with this cgroup
nonsense, then maybe we could get rid of all this.
next prev parent reply other threads:[~2023-11-07 9:53 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-07 9:05 [PATCH 0/4] sched/eevdf: Optimize reweight and pick Abel Wu
2023-11-07 9:05 ` [PATCH 1/4] sched/eevdf: Fix vruntime adjustment on reweight Abel Wu
2023-11-07 9:52 ` Peter Zijlstra [this message]
2023-11-14 21:57 ` [tip: sched/urgent] " tip-bot2 for Abel Wu
2023-11-15 15:36 ` [PATCH 1/4] " Yiwei Lin
2023-11-16 4:48 ` Abel Wu
2023-11-16 4:59 ` Yiwei Lin
2023-11-16 9:01 ` Abel Wu
2023-11-16 5:07 ` Abel Wu
2023-11-16 6:51 ` Yiwei Lin
2023-11-16 7:11 ` Abel Wu
2024-02-29 9:24 ` Tianchen Ding
2024-02-29 14:25 ` Abel Wu
2024-03-01 6:41 ` Tianchen Ding
2024-03-01 8:30 ` Abel Wu
2024-03-01 10:04 ` Tianchen Ding
2023-11-07 9:05 ` [PATCH 2/4] sched/eevdf: Sort the rbtree by virtual deadline Abel Wu
2023-11-07 11:03 ` Peter Zijlstra
2023-11-07 11:06 ` Abel Wu
2023-11-07 23:26 ` Benjamin Segall
2023-11-08 8:51 ` Abel Wu
2023-11-07 9:05 ` [PATCH 3/4] sched/eevdf: O(1) fastpath for task selection Abel Wu
2023-11-07 10:12 ` Abel Wu
2023-11-07 10:42 ` Peter Zijlstra
2023-11-07 9:05 ` [PATCH 4/4] sched/stats: branch statistics for pick_eevdf Abel Wu
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