linux-kernel - Re: [PATCH v2 00/15] timers: Cleanup delay/sleep related mess

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Message-ID: <c794b4a6-468d-4552-a6d6-8185f49339d3@wanadoo.fr>
Date: Mon, 16 Sep 2024 22:20:15 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Frederic Weisbecker <frederic@...nel.org>,
 Thomas Gleixner <tglx@...utronix.de>, Jonathan Corbet <corbet@....net>,
 Anna-Maria Behnsen <anna-maria@...utronix.de>
Cc: linux-kernel@...r.kernel.org, Len Brown <len.brown@...el.com>,
 "Rafael J. Wysocki" <rafael@...nel.org>,
 Anna-Maria Behnsen <anna-maria@...utronix.de>,
 Andrew Morton <akpm@...ux-foundation.org>, damon@...ts.linux.dev,
 linux-mm@...ck.org, SeongJae Park <sj@...nel.org>,
 Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org,
 Heiner Kallweit <hkallweit1@...il.com>, "David S. Miller"
 <davem@...emloft.net>, Andy Whitcroft <apw@...onical.com>,
 Joe Perches <joe@...ches.com>, Dwaipayan Ray <dwaipayanray1@...il.com>,
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
 Andrew Lunn <andrew@...n.ch>, Jaroslav Kysela <perex@...ex.cz>,
 Takashi Iwai <tiwai@...e.com>, netdev@...r.kernel.org,
 linux-sound@...r.kernel.org, Michael Ellerman <mpe@...erman.id.au>,
 Nathan Lynch <nathanl@...ux.ibm.com>, linuxppc-dev@...ts.ozlabs.org,
 Mauro Carvalho Chehab <mchehab@...nel.org>, linux-media@...r.kernel.org
Subject: Re: [PATCH v2 00/15] timers: Cleanup delay/sleep related mess

Le 11/09/2024 à 07:13, Anna-Maria Behnsen a écrit :
> Hi,
> 
> a question about which sleeping function should be used in acpi_os_sleep()
> started a discussion and examination about the existing documentation and
> implementation of functions which insert a sleep/delay.
> 
> The result of the discussion was, that the documentation is outdated and
> the implemented fsleep() reflects the outdated documentation but doesn't
> help to reflect reality which in turns leads to the queue which covers the
> following things:
> 
> - Split out all timeout and sleep related functions from hrtimer.c and timer.c
>    into a separate file
> 
> - Update function descriptions of sleep related functions
> 
> - Change fsleep() to reflect reality
> 
> - Rework all comments or users which obviously rely on the outdated
>    documentation as they reference "Documentation/timers/timers-howto.rst"
> 
> - Last but not least (as there are no more references): Update the outdated
>    documentation and move it into a file with a self explaining file name
> 
> The queue is available here and applies on top of tip/timers/core:
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/anna-maria/linux-devel.git timers/misc
> 
> Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>

Hi,

not directly related to your serie, but some time ago I sent a patch to 
micro-optimize Optimize usleep_range(). (See [1])

The idea is that the 2 parameters of usleep_range() are usually 
constants and some code reordering could easily let the compiler compute 
a few things at compilation time.

There was consensus on the value of the change (see [2]), but as you are 
touching things here, maybe it makes sense now to save a few cycles at 
runtime and a few bytes of code?

CJ

[1]: 
https://lore.kernel.org/all/f0361b83a0a0b549f8ec5ab8134905001a6f2509.1659126514.git.christophe.jaillet@wanadoo.fr/

[2]: 
https://lore.kernel.org/all/03c2bbe795fe4ddcab66eb852bae3715@AcuMS.aculab.com/