From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755487AbZAWPGt (ORCPT ); Fri, 23 Jan 2009 10:06:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753483AbZAWPGk (ORCPT ); Fri, 23 Jan 2009 10:06:40 -0500 Received: from smtp.ultrahosting.com ([74.213.174.254]:35305 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751070AbZAWPGj (ORCPT ); Fri, 23 Jan 2009 10:06:39 -0500 Date: Fri, 23 Jan 2009 10:03:22 -0500 (EST) From: Christoph Lameter X-X-Sender: cl@qirst.com To: Nick Piggin cc: Pekka J Enberg , yanmin_zhang@linux.intel.com, Andi Kleen , Matthew Wilcox , linux-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: Re: [PATCH] SLUB: revert direct page allocator pass through In-Reply-To: <200901231952.53961.nickpiggin@yahoo.com.au> Message-ID: References: <200901231952.53961.nickpiggin@yahoo.com.au> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 23 Jan 2009, Nick Piggin wrote: > Hmm, it lists quite a number of advantages that I guess are being > reverted too? What was the test case(s) that prompted this commit > in the first place? Better ensure it doesn't slow down... The advantage was mainly memory savings and abilty to redefined kmallocs to go directly to the page allocator. Totally avoids slab allocator overhead. I thought higher order allocations were not supposed to be used in performance critical paths? Didnt you want to do everything with order-0 allocs? It seems that we currently need the slab allocators to compensate for the performance problems in the page allocator for these higher order allocs. I'd rather have the page allocator fixed but things are as they are.