From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754140AbZC3HLr (ORCPT ); Mon, 30 Mar 2009 03:11:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752323AbZC3HLf (ORCPT ); Mon, 30 Mar 2009 03:11:35 -0400 Received: from courier.cs.helsinki.fi ([128.214.9.1]:44975 "EHLO mail.cs.helsinki.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751013AbZC3HLf (ORCPT ); Mon, 30 Mar 2009 03:11:35 -0400 Subject: Re: [patch 1/3] slub: add per-cache slab thrash ratio From: Pekka Enberg To: David Rientjes Cc: Christoph Lameter , Nick Piggin , Martin Bligh , linux-kernel@vger.kernel.org, Mel Gorman In-Reply-To: References: Date: Mon, 30 Mar 2009 10:11:31 +0300 Message-Id: <1238397091.26742.35.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit X-Mailer: Evolution 2.22.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2009-03-29 at 22:43 -0700, David Rientjes wrote: > The slab_thrash_ratio for each cache do not have non-zero defaults > (yet?). If we're going to merge this code, I think it would be better to put a non-zero default there; otherwise we won't be able to hit potential performance regressions or bugs. Furthermore, the optimization is not very useful on large scale if people need to enable it themselves. Maybe stick 20 there and run tbench, sysbench, et al to see if it makes a difference? I'm cc'ing Mel in case he has some suggestions how to test it. Pekka