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Date:   Wed, 15 Nov 2023 13:20:27 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Cruz Zhao <CruzZhao@linux.alibaba.com>
Cc:     mingo@redhat.com, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com, vschneid@redhat.com, joel@joelfernandes.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] sched/fair: introduce core_vruntime and
 core_min_vruntime
Message-ID: <20231115122027.GZ8262@noisy.programming.kicks-ass.net>
References: <20231115113341.13261-1-CruzZhao@linux.alibaba.com>
 <20231115113341.13261-4-CruzZhao@linux.alibaba.com>
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In-Reply-To: <20231115113341.13261-4-CruzZhao@linux.alibaba.com>
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On Wed, Nov 15, 2023 at 07:33:40PM +0800, Cruz Zhao wrote:
> To compare the priority of sched_entity from different cpus of a core,
> we introduce core_vruntime to struct sched_entity and core_min_vruntime
> to struct cfs_rq.
> 
> cfs_rq->core->core_min_vruntime records the min vruntime of the cfs_rqs
> of the same task_group among the core, and se->core_vruntime is the
> vruntime relative to se->cfs_rq->core->core_min_vruntime.

But that makes absolutely no sense. vruntime of different RQs can
advance at wildly different rates. Not to mention there's this random
offset between them.

No, this cannot be.