linux-kernel - Re: [PATCH v2 4/6] mm: Only IPI CPUs to drain local pages if they exist

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Date:	Fri, 28 Oct 2011 10:43:31 +0200
From:	Gilad Ben-Yossef <gilad@...yossef.com>
To:	Christoph Lameter <cl@...two.org>
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Russell King <linux@....linux.org.uk>, linux-mm@...ck.org,
	Pekka Enberg <penberg@...nel.org>,
	Matt Mackall <mpm@...enic.com>,
	Sasha Levin <levinsasha928@...il.com>
Subject: Re: [PATCH v2 4/6] mm: Only IPI CPUs to drain local pages if they exist

On Fri, Oct 28, 2011 at 6:10 AM, Christoph Lameter <cl@...two.org> wrote:
> On Sun, 23 Oct 2011, Gilad Ben-Yossef wrote:
>
>> +/* Which CPUs have per cpu pages  */
>> +cpumask_var_t cpus_with_pcp;
>> +static DEFINE_PER_CPU(unsigned long, total_cpu_pcp_count);
>
> This increases the cache footprint of a hot vm path. Is it possible to do
> the same than what you did for slub? Run a loop over all zones when
> draining to check for remaining pcp pages and build the set of cpus
> needing IPIs temporarily while draining?
>

Sounds like a good idea. I will give it a shot.

Thanks,
Gilad




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