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Message-ID: <4692E7D4.6060909@yahoo.com.au>
Date: Tue, 10 Jul 2007 11:58:44 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Christoph Lameter <clameter@sgi.com>
CC: Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>,
       linux-kernel@vger.kernel.org, linux-mm@vger.kernel.org,
       suresh.b.siddha@intel.com, corey.d.gough@intel.com,
       Pekka Enberg <penberg@cs.helsinki.fi>, Matt Mackall <mpm@selenic.com>,
       Denis Vlasenko <vda.linux@googlemail.com>,
       Erik Andersen <andersen@codepoet.org>
Subject: Re: [patch 09/10] Remove the SLOB allocator for 2.6.23
References: <20070708034952.022985379@sgi.com> <20070708035018.074510057@sgi.com> <20070708075119.GA16631@elte.hu> <20070708110224.9cd9df5b.akpm@linux-foundation.org> <4691A415.6040208@yahoo.com.au> <Pine.LNX.4.64.0707090901410.13970@schroedinger.engr.sgi.com> <4692E3BF.9010305@yahoo.com.au> <Pine.LNX.4.64.0707091849590.2860@schroedinger.engr.sgi.com>
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Christoph Lameter wrote:
> On Tue, 10 Jul 2007, Nick Piggin wrote:
> 
> 
>>>O(n) memory savings? What is that?
>>
>>Allocate n things and your memory waste is proportional to n (well that's
>>O(n) waste, so I guess by savings I mean that SLOB's memory saving compared
>>to SLUB are proportional to n).
> 
> 
> n is the size of the object?

n things -- n number of things (n calls to kmem_cache_alloc()).

Just a fancy way of saying roughly that memory waste will increase as
the size of the system increases. But that aspect of it I think is
not really a problem for non-tiny systems anyway because the waste
tends not to be too bad (and possibly the number of active allocations
does not increase O(n) with the size of RAM either).

-- 
SUSE Labs, Novell Inc.