linux-kernel - Re: [PATCH v4 4/5] slub: Only IPI CPUs that have per cpu obj to flush

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Date:	Wed, 23 Nov 2011 09:52:47 +0200
From:	Gilad Ben-Yossef <gilad@...yossef.com>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Chris Metcalf <cmetcalf@...era.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Russell King <linux@....linux.org.uk>, linux-mm@...ck.org,
	Matt Mackall <mpm@...enic.com>,
	Sasha Levin <levinsasha928@...il.com>,
	Rik van Riel <riel@...hat.com>,
	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v4 4/5] slub: Only IPI CPUs that have per cpu obj to flush

On Wed, Nov 23, 2011 at 8:57 AM, Pekka Enberg <penberg@...nel.org> wrote:
> On Wed, Nov 23, 2011 at 8:23 AM, Pekka Enberg <penberg@...nel.org> wrote:
>> On Tue, 22 Nov 2011, Gilad Ben-Yossef wrote:
>>>
>>> static void flush_all(struct kmem_cache *s)
>>> {
>>> -       on_each_cpu(flush_cpu_slab, s, 1);
>>> +       cpumask_var_t cpus;
>>> +       struct kmem_cache_cpu *c;
>>> +       int cpu;
>>> +
>>> +       if (likely(zalloc_cpumask_var(&cpus, GFP_ATOMIC))) {
>>
>> __GFP_NOWARN too maybe?
>>

Right, the allocation failure here is harmless. I should probably do
the same for the page_alloc.c case as well.

>>> +               for_each_online_cpu(cpu) {
>>> +                       c = per_cpu_ptr(s->cpu_slab, cpu);
>>> +                       if (c->page)
>>> +                               cpumask_set_cpu(cpu, cpus);
>>> +               }
>>> +               on_each_cpu_mask(cpus, flush_cpu_slab, s, 1);
>>> +               free_cpumask_var(cpus);
>>> +       } else
>>> +               on_each_cpu(flush_cpu_slab, s, 1);
>>> }
>>
>> Acked-by: Pekka Enberg <penberg@...nel.org>
>>
>> I can't take the patch because it depends on a new API introduced in the
>> first patch.
>>
>> I'm CC'ing Andrew.

Thanks!

There's a git tree of these over at: git://github.com/gby/linux.git
branch ipi_noise_v4 in case that helps.

I will send v5 (and create a new git branch for it) with the above
changes and the Arm patch  description update once I get an Ack from
Russel K.

Cheers,
Gilad

>



-- 
Gilad Ben-Yossef
Chief Coffee Drinker
gilad@...yossef.com
Israel Cell: +972-52-8260388
US Cell: +1-973-8260388
http://benyossef.com

"Unfortunately, cache misses are an equal opportunity pain provider."
-- Mike Galbraith, LKML
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