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

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Message-ID: <CAOtvUMd8Z_jbs__+cVG2+ZkPZLqGkJGym402RMRYGDDjT73bkg@mail.gmail.com>
Date:	Sat, 29 Oct 2011 17:29:41 +0200
From:	Gilad Ben-Yossef <gilad@...yossef.com>
To:	Rik van Riel <riel@...hat.com>
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,
	Christoph Lameter <cl@...ux-foundation.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 6:07 PM, Rik van Riel <riel@...hat.com> wrote:
> On 10/23/2011 11:56 AM, Gilad Ben-Yossef wrote:
>>
>> Use a cpumask to track CPUs with per-cpu pages in any zone
>> and only send an IPI requesting CPUs to drain these pages
>> to the buddy allocator if they actually have pages.
>
>> +/* Which CPUs have per cpu pages  */
>> +cpumask_var_t cpus_with_pcp;
>> +static DEFINE_PER_CPU(unsigned long, total_cpu_pcp_count);
>
> Does the flushing happen so frequently that it is worth keeping this
> state on a per-cpu basis, or would it be better to check each CPU's
> pcp info and assemble a cpumask at flush time like done in patch 5?
>

No, I don't  believe it is frequent at all. I will try to re-work the
patch as suggested.

Thanks,
Gilad

>

>
> --
> All rights reversed
>



-- 
Gilad Ben-Yossef
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gilad@...yossef.com
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