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Date: Tue, 17 Feb 2009 21:43:10 +0200
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Subject: Re: [patch] SLQB slab allocator (try 2)
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux-foundation.org>, Mel Gorman <mel@csn.ul.ie>,
       Nick Piggin <nickpiggin@yahoo.com.au>, Nick Piggin <npiggin@suse.de>,
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       "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
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On Tue, Feb 17, 2009 at 12:05:07PM -0500, Christoph Lameter wrote:
>> Index: linux-2.6/include/linux/slub_def.h
>> ===================================================================
>> --- linux-2.6.orig/include/linux/slub_def.h   2009-02-17 10:45:51.000000000 -0600
>> +++ linux-2.6/include/linux/slub_def.h        2009-02-17 11:06:53.000000000 -0600
>> @@ -121,10 +121,21 @@
>>  #define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE)
>>
>>  /*
>> + * Maximum kmalloc object size handled by SLUB. Larger object allocations
>> + * are passed through to the page allocator. The page allocator "fastpath"
>> + * is relatively slow so we need this value sufficiently high so that
>> + * performance critical objects are allocated through the SLUB fastpath.
>> + *
>> + * This should be dropped to PAGE_SIZE / 2 once the page allocator
>> + * "fastpath" becomes competitive with the slab allocator fastpaths.
>> + */
>> +#define SLUB_MAX_SIZE (2 * PAGE_SIZE)

On Tue, Feb 17, 2009 at 8:11 PM, Johannes Weiner <hannes@cmpxchg.org> wrote:
> This relies on PAGE_SIZE being 4k.  If you want 8k, why don't you say
> so?  Pekka did this explicitely.

That could be a problem, sure. Especially for architecture that have 64 K pages.