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From: Tejun Heo <tj@kernel.org>
To: Tao Cui <cui.tao@linux.dev>
Cc: void@manifault.com, arighi@nvidia.com, changwoo@igalia.com,
	michalblk@google.com, liwanwu@kylinos.cn,
	sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org,
	bpf@vger.kernel.org, Tao Cui <cuitao@kylinos.cn>
Subject: Re: [PATCH 1/2] sched_ext: fix vtime priority queue inversion on wide vtime spread
Date: Mon, 31 Aug 2026 22:29:16 -1000	[thread overview]
Message-ID: <apaM3G2AJmYkGJW-@slm.duckdns.org> (raw)
In-Reply-To: <20260901024038.730424-2-cui.tao@linux.dev>

Hello,

On Tue, Sep 01, 2026 at 10:40:37AM +0800, Tao Cui wrote:
...
> than 2^63 apart. Unlike CFS, which enforces that invariant with
> min_vruntime clamping, sched_ext takes dsq_vtime directly from the BPF
> scheduler and cannot bound the spread. A scheduler that inserts tasks

This doesn't make any practical sense. dsq_vtime is by (implicit) definition
a rolling cursor. Please feel free to add documentation if that'd help.

Thanks.

-- 
tejun

  parent reply	other threads:[~2026-09-01  8:29 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-01  2:40 [PATCH 0/2] sched_ext: fix wraparound-unsafe vtime orderings Tao Cui
2026-09-01  2:40 ` [PATCH 1/2] sched_ext: fix vtime priority queue inversion on wide vtime spread Tao Cui
2026-09-01  2:54   ` sashiko-bot
2026-09-01  6:47   ` Andrea Righi
2026-09-01  9:44     ` Tao Cui
2026-09-01  8:29   ` Tejun Heo [this message]
2026-09-01  2:40 ` [PATCH 2/2] sched_ext/scx_flatcg: make cgv_node_less() wraparound-safe Tao Cui
2026-09-01  2:51   ` sashiko-bot
2026-09-01  3:54   ` bot+bpf-ci

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