Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934297AbZJMUQn (ORCPT ); Tue, 13 Oct 2009 16:16:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755959AbZJMUQn (ORCPT ); Tue, 13 Oct 2009 16:16:43 -0400 Received: from smtp-out.google.com ([216.239.45.13]:35230 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751780AbZJMUQm (ORCPT ); Tue, 13 Oct 2009 16:16:42 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=WSEQKH43ACZFPlyzZxk6curmyrQu5Ld5fRs6Q+Wqksy8q0BXecs7YoWoQi01mNyDj ax3H1hBgWc8wAQ/H9jtuw== Date: Tue, 13 Oct 2009 13:15:27 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Christoph Lameter cc: Pekka Enberg , Tejun Heo , linux-kernel@vger.kernel.org, Mathieu Desnoyers , Mel Gorman , Zhang Yanmin Subject: Re: [this_cpu_xx V6 7/7] this_cpu: slub aggressive use of this_cpu operations in the hotpaths In-Reply-To: Message-ID: References: <20091007211024.442168959@gentwo.org> <20091007211053.378634196@gentwo.org> <4AD307A5.105@kernel.org> <84144f020910120614r529d8e4em9babe83a90e9371f@mail.gmail.com> <4AD4D8B6.6010700@cs.helsinki.fi> User-Agent: Alpine 1.00 (DEB 882 2007-12-20) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1245 Lines: 30 On Tue, 13 Oct 2009, Christoph Lameter wrote: > > I wonder how reliable these numbers are. We did similar testing a while back > > because we thought kmalloc-96 caches had weird cache behavior but finally > > figured out the anomaly was explained by the order of the tests run, not cache > > size. > > Well you need to look behind these numbers to see when the allocator uses > the fastpath or slow path. Only the fast path is optimized here. > With the netperf -t TCP_RR -l 60 benchmark I ran, CONFIG_SLUB_STATS shows the allocation fastpath is utilized quite a bit for a couple of key caches: cache ALLOC_FASTPATH ALLOC_SLOWPATH kmalloc-256 98125871 31585955 kmalloc-2048 77243698 52347453 For an optimized fastpath, I'd expect such a workload would result in at least a slightly higher transfer rate. I'll try the irqless patch, but this particular benchmark may not appropriately demonstrate any performance gain because of the added code in the also significantly-used slowpath. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/