From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753856Ab0INVAX (ORCPT ); Tue, 14 Sep 2010 17:00:23 -0400 Received: from freeflow.nu ([178.79.134.28]:52366 "EHLO freeflow.nu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752751Ab0INVAW (ORCPT ); Tue, 14 Sep 2010 17:00:22 -0400 Message-ID: <4C8FE263.5070101@kernel.org> Date: Wed, 15 Sep 2010 00:00:19 +0300 From: Pekka Enberg User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9.2.8) Gecko/20100802 Thunderbird/3.1.2 MIME-Version: 1.0 To: David Rientjes CC: Linus Torvalds , linux-kernel@vger.kernel.org, Christoph Lameter Subject: Re: [PATCH v2 2/2] SLUB: Mark merged slab caches in /proc/slabinfo References: <1284490101-2362-1-git-send-email-penberg@kernel.org> <1284490101-2362-2-git-send-email-penberg@kernel.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14.9.2010 23.56, David Rientjes wrote: >> In my not-so-humble opinion, either the merging needs to go away >> entirely, or the misleading output needs to be fixed. > Cache merging may have been advertised as a bigger performance improvement > than it actually is, and I don't do it in my own slab allocator for other > reasons, but it does lead to more effective memory use by reducing slab > fragmentation. On one of my benchmarking servers, over 60% of caches are > merged and /sys/kernel/slab/.../partial reports roughly the same percent > of fewer total partial slabs over the system in comparison to > slub_nomerge. Last time I checked (and it's been a while), it did reduce _internal fragmentation_ for the naive "memory used after boot" scenario. I don't think I ever advertised it as a performance improvement. Dunno if somebody else did. Pekka