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From: Oleg Nesterov <oleg@tv-sign.ru>
To: Jarek Poplawski <jarkao2@o2.pl>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	David Howells <dhowells@redhat.com>,
	David Miller <davem@davemloft.net>, Ingo Molnar <mingo@elte.hu>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] cancel_delayed_work: use del_timer() instead of del_timer_sync()
Date: Wed, 25 Apr 2007 16:52:14 +0400	[thread overview]
Message-ID: <20070425125214.GB94@tv-sign.ru> (raw)
In-Reply-To: <20070425130246.GA4086@ff.dom.local>

On 04/25, Jarek Poplawski wrote:
>
> On Wed, Apr 25, 2007 at 01:50:34AM +0400, Oleg Nesterov wrote:
> > del_timer_sync() buys nothing for cancel_delayed_work(), but it is less
> > efficient since it locks the timer unconditionally, and may wait for the
> > completion of the delayed_work_timer_fn().
> 
> I'm not sure what is the main aim of this patch.

optimization

>                                                  It seems this
> change cannot do any harm, but anyway it could change a few
> things, e.g. with current version of cancel_rearming_delayed_work
> some flush_workqueue could be done needlessly, before the work
> is queued from timer.

I don't think so... Could you clarify?

>                       It's not a big deal here, but if anybody
> did something like this without loop - it could matter.
> 
> So, probably a lot of current code should be checked, before
> applying and I doubt the gain is worth of this. Maybe, for
> safety, make this with new name as an alternative and
> deprecate the current version?

This change should not make any visible difference for the callers,
otherwise it is buggy.

Oleg.


  reply	other threads:[~2007-04-25 13:47 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-24 21:50 Oleg Nesterov
2007-04-25 10:04 ` David Howells
2007-04-25 13:02 ` Jarek Poplawski
2007-04-25 12:52   ` Oleg Nesterov [this message]
2007-04-26 14:29     ` Jarek Poplawski
2007-04-26 15:29       ` Oleg Nesterov
2007-04-27  6:15         ` Jarek Poplawski
2007-04-27  7:23           ` Oleg Nesterov

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