From: Ezequiel Garcia <elezegarcia@gmail.com>
To: Tim Bird <tim.bird@am.sony.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
David Rientjes <rientjes@google.com>,
Andi Kleen <andi@firstfloor.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"celinux-dev@lists.celinuxforum.org"
<celinux-dev@lists.celinuxforum.org>
Subject: Re: [Q] Default SLAB allocator
Date: Tue, 16 Oct 2012 15:36:44 -0300 [thread overview]
Message-ID: <CALF0-+XLXAh3=OScQ=V0F80ZcnTGjHox68SApOwPUYVvmjdqPw@mail.gmail.com> (raw)
In-Reply-To: <507DA245.9050709@am.sony.com>
On Tue, Oct 16, 2012 at 3:07 PM, Tim Bird <tim.bird@am.sony.com> wrote:
> On 10/16/2012 05:56 AM, Eric Dumazet wrote:
>> On Tue, 2012-10-16 at 09:35 -0300, Ezequiel Garcia wrote:
>>
>>> Now, returning to the fragmentation. The problem with SLAB is that
>>> its smaller cache available for kmalloced objects is 32 bytes;
>>> while SLUB allows 8, 16, 24 ...
>>>
>>> Perhaps adding smaller caches to SLAB might make sense?
>>> Is there any strong reason for NOT doing this?
>>
>> I would remove small kmalloc-XX caches, as sharing a cache line
>> is sometime dangerous for performance, because of false sharing.
>>
>> They make sense only for very small hosts.
>
> That's interesting...
>
> It would be good to measure the performance/size tradeoff here.
> I'm interested in very small systems, and it might be worth
> the tradeoff, depending on how bad the performance is. Maybe
> a new config option would be useful (I can hear the groans now... :-)
>
It might be worth reminding that very small systems can use SLOB
allocator, which does not suffer from this kind of fragmentation.
Ezequiel
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next prev parent reply other threads:[~2012-10-16 18:36 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-11 14:19 Ezequiel Garcia
2012-10-11 22:42 ` Andi Kleen
2012-10-11 22:59 ` David Rientjes
2012-10-11 23:10 ` Andi Kleen
2012-10-12 12:07 ` Ezequiel Garcia
2012-10-13 9:54 ` David Rientjes
2012-10-13 12:44 ` Ezequiel Garcia
2012-10-16 0:46 ` David Rientjes
2012-10-16 12:35 ` Ezequiel Garcia
2012-10-16 12:56 ` Eric Dumazet
2012-10-16 18:07 ` Tim Bird
2012-10-16 18:27 ` Ezequiel Garcia
2012-10-16 18:44 ` Tim Bird
2012-10-16 18:49 ` Ezequiel Garcia
2012-10-16 19:16 ` Eric Dumazet
2012-10-17 18:45 ` Tim Bird
2012-10-17 19:13 ` Eric Dumazet
2012-10-17 19:20 ` Shentino
2012-10-17 20:33 ` Tim Bird
2012-10-18 0:46 ` Shentino
2012-10-17 20:58 ` Tim Bird
2012-10-17 21:05 ` Ezequiel Garcia
2012-10-16 18:36 ` Ezequiel Garcia [this message]
2012-10-16 18:54 ` Christoph Lameter
2012-10-13 9:51 ` David Rientjes
2012-10-13 15:10 ` Eric Dumazet
2012-10-16 1:28 ` JoonSoo Kim
2012-10-16 7:23 ` Eric Dumazet
2012-10-19 0:03 ` JoonSoo Kim
2012-10-19 7:01 ` Eric Dumazet
2012-10-16 0:45 ` David Rientjes
2012-10-16 18:53 ` Christoph Lameter
2012-10-16 19:02 ` Christoph Lameter
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