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Date: Thu, 19 Feb 2009 21:51:48 +0900
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Message-ID: <2f11576a0902190451w294aa2fan29b61fa3619f459b@mail.gmail.com>
Subject: Re: [patch] SLQB slab allocator (try 2)
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <cl@linux-foundation.org>,
       Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mel@csn.ul.ie>,
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       Linux Memory Management List <linux-mm@kvack.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Lin Ming <ming.m.lin@intel.com>,
       "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
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2009/2/19 Pekka Enberg <penberg@cs.helsinki.fi>:
> On Wed, 2009-02-18 at 09:48 +0900, KOSAKI Motohiro wrote:
>> > > In addition, if pekka patch (SLAB_LIMIT = 8K) run on ia64, 16K allocation
>> > > always fallback to page allocator and using 64K (4 times memory consumption!).
>> >
>> > Yes, correct, but SLUB does that already by passing all allocations over
>> > 4K to the page allocator.
>>
>> hmhm
>> OK. my mail was pointless.
>>
>> but why? In my understanding, slab framework mainly exist for efficient
>> sub-page allocation.
>> the fallbacking of 4K allocation in 64K page-sized architecture seems
>> inefficient.
>
> I don't think any of the slab allocators are known for memory
> efficiency. That said, the original patch description sums up the
> rationale for page allocator pass-through:
>
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=aadb4bc4a1f9108c1d0fbd121827c936c2ed4217
>
> Interesting enough, there seems to be some performance gain from it as
> well as seen by Mel Gorman's recent slab allocator benchmarks.

Honestly, I'm bit confusing.
above url's patch use PAGE_SIZE, but not 4K nor architecture independent value.
Your 4K mean PAGE_SIZE?