linux-kernel - Re: [PATCH 19/39] sched_ext: Print sched

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Date: Mon, 24 Jun 2024 10:25:00 -0400
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Tejun Heo <tj@...nel.org>, mingo@...hat.com, juri.lelli@...hat.com, 
	vincent.guittot@...aro.org, dietmar.eggemann@....com, rostedt@...dmis.org, 
	bsegall@...gle.com, mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com, 
	ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	martin.lau@...nel.org, joshdon@...gle.com, brho@...gle.com, pjt@...gle.com, 
	derkling@...gle.com, haoluo@...gle.com, dvernet@...a.com, 
	dschatzberg@...a.com, dskarlat@...cmu.edu, riel@...riel.com, 
	changwoo@...lia.com, himadrics@...ia.fr, memxor@...il.com, 
	andrea.righi@...onical.com, joel@...lfernandes.org, 
	linux-kernel@...r.kernel.org, bpf@...r.kernel.org, kernel-team@...a.com, 
	David Vernet <void@...ifault.com>
Subject: Re: [PATCH 19/39] sched_ext: Print sched_ext info when dumping stack

On Mon, 24 Jun 2024 at 08:46, Peter Zijlstra <peterz@...radead.org> wrote:
>
> Also, if we consider 2s complement, does the above actually make sense?

jiffies_to_msecs() does not work on 2s complement. It just takes
'unsigned long', and just considers large positive numbers to be
exactly that - not a negative jiffy.

We have a separate jiffies_delta_to_msecs(), but that clamps to zero.
So again, it doesn't actually work for negative jiffies.

Side note: jiffies_to_msecs() seems to return an "unsigned int". That
seems a bit odd.

             Linus