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Subject: Re: [patch 3/7] mm: make page writeback obey cpuset constraints
From: Peter Zijlstra <peterz@infradead.org>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Christoph Lameter <cl@linux-foundation.org>,
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       Derek Fults <dfults@sgi.com>, linux-kernel@vger.kernel.org
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Date: Thu, 30 Oct 2008 09:42:00 +0100
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On Tue, 2008-10-28 at 12:18 -0700, David Rientjes wrote:
> On Tue, 28 Oct 2008, Peter Zijlstra wrote:
> 
> > > +	is_subset = cpuset_populate_dirty_limits(dl, &dirtyable_memory,
> > > +						 &nr_mapped, nodes);
> > > +	if (!is_subset) {
> > > +		dl->nr_dirty = global_page_state(NR_FILE_DIRTY);
> > > +		dl->nr_unstable = global_page_state(NR_UNSTABLE_NFS);
> > > +		dl->nr_writeback = global_page_state(NR_WRITEBACK);
> > > +		dirtyable_memory = determine_dirtyable_memory();
> > > +		nr_mapped = global_page_state(NR_FILE_MAPPED) +
> > > +			global_page_state(NR_ANON_PAGES);
> > > +	} else
> > > +		dirtyable_memory -= highmem_dirtyable_memory(nodes,
> > > +							dirtyable_memory);
> > 
> > Why not fold that all into cpuset_populate_dirty_limits() ?
> > 
> 
> cpuset_populate_dirty_limits() is a no-op on !CONFIG_CPUSETS kernels.

Right, humm. Maybe introduce a populate_dirty_limits() and differentiate
that between CONFIG_CPUSETS and not, and make it do everything.

That would get rid of this fudge I think, no?