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From: David Rientjes <rientjes@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@linux-foundation.org>,
	Nick Piggin <npiggin@suse.de>, Paul Menage <menage@google.com>,
	Derek Fults <dfults@sgi.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [patch 6/7] cpusets: per cpuset dirty ratios
Date: Thu, 30 Oct 2008 02:03:14 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.00.0810300154040.29917@chino.kir.corp.google.com> (raw)
In-Reply-To: <1225356285.7803.7.camel@twins>

On Thu, 30 Oct 2008, Peter Zijlstra wrote:

> On Tue, 2008-10-28 at 09:08 -0700, David Rientjes wrote:
> 
> > +/*
> > + * Determine the dirty ratios for the currently active cpuset
> > + */
> > +void cpuset_get_current_dirty_ratios(int *background, int *throttle)
> > +{
> > +	mutex_lock(&callback_mutex);
> > +	task_lock(current);
> > +	*background = task_cs(current)->dirty_background_ratio;
> > +	*throttle = task_cs(current)->cpuset_dirty_ratio;
> > +	task_unlock(current);
> > +	mutex_unlock(&callback_mutex);
> > +
> > +	if (*background == -1)
> > +		*background = dirty_background_ratio;
> > +	if (*throttle == -1)
> > +		*throttle = vm_dirty_ratio;
> > +}
> 
> That's rather an awful lot of locking to read just two integers.
> 

As far as I know, task_lock(current) is required to dereference 
task_cs(current) and callback_mutex is required to ensure its the same 
cpuset.

  reply	other threads:[~2008-10-30  9:04 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-28 16:08 [patch 1/7] cpusets: add dirty map to struct address_space David Rientjes
2008-10-28 16:08 ` [patch 2/7] pdflush: allow the passing of a nodemask parameter David Rientjes
2008-10-28 16:08 ` [patch 3/7] mm: make page writeback obey cpuset constraints David Rientjes
2008-10-28 17:31   ` Peter Zijlstra
2008-10-28 19:16     ` David Rientjes
2008-10-28 17:32   ` Peter Zijlstra
2008-10-28 19:18     ` David Rientjes
2008-10-30  8:42       ` Peter Zijlstra
2008-10-30  9:10         ` David Rientjes
2008-10-30  9:34           ` Peter Zijlstra
2008-10-28 16:08 ` [patch 4/7] mm: cpuset aware reclaim writeout David Rientjes
2008-10-28 16:08 ` [patch 5/7] mm: throttle writeout with cpuset awareness David Rientjes
2008-10-28 16:08 ` [patch 6/7] cpusets: per cpuset dirty ratios David Rientjes
2008-10-30  6:59   ` Paul Menage
2008-10-30  8:48     ` David Rientjes
2008-10-30 15:28     ` Christoph Lameter
2008-10-30  8:44   ` Peter Zijlstra
2008-10-30  9:03     ` David Rientjes [this message]
2008-10-30  9:34       ` Peter Zijlstra
2008-10-30 10:02         ` David Rientjes
2008-10-28 16:08 ` [patch 7/7] cpusets: update documentation for writeback throttling David Rientjes
2008-10-30 16:06   ` Christoph Lameter
2008-10-28 17:37 ` [patch 1/7] cpusets: add dirty map to struct address_space Peter Zijlstra
2008-10-28 20:48   ` David Rientjes
2008-10-29  1:13     ` David Rientjes
2008-10-29  2:24       ` David Rientjes
2008-10-30  8:38       ` Peter Zijlstra
2008-10-28 17:46 ` Peter Zijlstra
2008-10-28 19:19   ` David Rientjes
2008-10-30 19:23 [patch 0/7] cpuset writeback throttling David Rientjes
2008-10-30 19:23 ` [patch 6/7] cpusets: per cpuset dirty ratios David Rientjes

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