From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id D84896B003D for ; Thu, 19 Feb 2009 04:16:10 -0500 (EST) Subject: Re: [patch] SLQB slab allocator (try 2) From: Pekka Enberg In-Reply-To: <20090219085229.954A.A69D9226@jp.fujitsu.com> References: <20090218093858.8990.A69D9226@jp.fujitsu.com> <1234944569.24030.20.camel@penberg-laptop> <20090219085229.954A.A69D9226@jp.fujitsu.com> Date: Thu, 19 Feb 2009 11:16:07 +0200 Message-Id: <1235034967.29813.10.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Christoph Lameter , Johannes Weiner , Mel Gorman , Nick Piggin , Nick Piggin , Linux Memory Management List , Linux Kernel Mailing List , Andrew Morton , Lin Ming , "Zhang, Yanmin" List-ID: 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. Pekka -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org