linux-kernel - Re: [PATCH] Move memory controller allocations to their own slabs (v2)

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Message-ID: <47D66865.1080508@linux.vnet.ibm.com>
Date:	Tue, 11 Mar 2008 16:39:25 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Pavel Emelyanov <xemul@...nvz.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hugh@...itas.com>,
	Sudhir Kumar <skumar@...ux.vnet.ibm.com>,
	YAMAMOTO Takashi <yamamoto@...inux.co.jp>,
	Paul Menage <menage@...gle.com>, lizf@...fujitsu.com,
	linux-kernel@...r.kernel.org, taka@...inux.co.jp,
	linux-mm@...ck.org, David Rientjes <rientjes@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH] Move memory controller allocations to their own slabs
 (v2)

Pavel Emelyanov wrote:
> Balbir Singh wrote:
>> Pavel Emelyanov wrote:
>>> Balbir Singh wrote:
>>>> Move the memory controller data structure page_cgroup to its own slab cache.
>>>> It saves space on the system, allocations are not necessarily pushed to order
>>>> of 2 and should provide performance benefits. Users who disable the memory
>>>> controller can also double check that the memory controller is not allocating
>>>> page_cgroup's.
>>> Can you, please, check how many objects-per-page we have with and 
>>> without this patch for SLAB and SLUB?
>>>
>>> Thanks.
>> I can for objects-per-page with this patch for SLUB and SLAB. I am not sure
>> about what to check for without this patch. The machine is temporarily busy,
> 
> Well, the objects-per-page without the patch is objects-per-page for
> according kmalloc cache :)
> 

OK, so here is the data

On my 64 bit powerpc system (structure size could be different on other systems)

1. sizeof page_cgroup is 40 bytes
   which means kmalloc will allocate 64 bytes
2. With 4K pagesize SLAB with HWCACHE_ALIGN, 59 objects are packed per slab
3. With SLUB the value is 102 per slab



-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL
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