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From: Arjan van de Ven <arjan@infradead.org>
To: Roman Zippel <zippel@linux-m68k.org>
Cc: Jonathan Corbet <corbet@lwn.net>,
	linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	akpm@linux-foundation.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] msleep() with hrtimers
Date: Tue, 07 Aug 2007 21:15:12 -0700	[thread overview]
Message-ID: <1186546512.2862.3.camel@laptopd505.fenrus.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0708071417200.1817@scrub.home>

On Tue, 2007-08-07 at 14:45 +0200, Roman Zippel wrote:
> Hi,
> 
> On Mon, 6 Aug 2007, Arjan van de Ven wrote:
> 
> > So, let me ask a direct question: What do you think is specifically
> > wrong about changing the msleep() implementation as is done here? The
> > behavior is clearly an improvement, so what is your objection on the
> > flipside?
> 
> Again, we have two different timer APIs for a reason

yes because we have different usage patterns for timers. (exact/course
or expiring/not-typically-expiring; I know you have some other opinion
here than other people).

For this case it's relatively simple imo: The existing implementation
has a *typical* behavior which is 100% to 2000% worse than what the user
of the API asks for. And that is totally unneeded to be so crappy; it
can be much more exact easily as shown by this patch.

You keep claiming that hrtimers are so incredibly expensive; but for
msleep()... which is mostly called during driver init ... I really don't
buy that it's really expensive. We're not doing this a gazilion times
per second obviously...

-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org


  reply	other threads:[~2007-08-08  4:17 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-03 18:37 [PATCH] msleep() with hrtimers Jonathan Corbet
2007-08-03 18:54 ` Ingo Molnar
2007-08-03 19:19 ` Roman Zippel
2007-08-03 19:46   ` Arjan van de Ven
2007-08-03 19:58     ` Roman Zippel
2007-08-03 23:53       ` Arjan van de Ven
2007-08-04  3:00         ` Roman Zippel
2007-08-04 19:19           ` Arjan van de Ven
2007-08-06  0:09             ` Roman Zippel
2007-08-06  0:43               ` Arjan van de Ven
2007-08-06  1:03                 ` Roman Zippel
2007-08-06  5:39                   ` Arjan van de Ven
2007-08-06 10:03                     ` Roman Zippel
2007-08-06 10:20                       ` Manu Abraham
2007-08-06 15:53                       ` Arjan van de Ven
2007-08-07 10:40                         ` Manu Abraham
2007-08-07 12:45                         ` Roman Zippel
2007-08-08  4:15                           ` Arjan van de Ven [this message]
2007-08-09 19:31                             ` Denis Vlasenko
2007-08-09 20:01                               ` Denis Vlasenko
2007-08-07 19:40 ` Andrew Morton
2007-08-07 23:16   ` Roman Zippel
2007-08-07 23:29     ` Andrew Morton
2007-08-08  3:47       ` Roman Zippel
2007-08-08  4:14         ` Andrew Morton
2007-08-09 22:31           ` Roman Zippel
2007-08-08 11:55   ` Andi Kleen
2007-08-08 11:09     ` Manu Abraham
2007-08-08 11:52       ` Andi Kleen
2007-08-08 11:59         ` Manu Abraham
2007-08-09  7:16 ` Andrew Morton
2007-08-09 15:08   ` [linux-usb-devel] " Alan Stern
2007-11-28 10:29 ` Andrew Morton

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