From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758925AbYEHDf1 (ORCPT ); Wed, 7 May 2008 23:35:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755164AbYEHDfF (ORCPT ); Wed, 7 May 2008 23:35:05 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:37723 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754809AbYEHDfB (ORCPT ); Wed, 7 May 2008 23:35:01 -0400 Date: Wed, 7 May 2008 20:34:40 -0700 (PDT) From: Linus Torvalds To: "Zhang, Yanmin" cc: Matthew Wilcox , Ingo Molnar , "J. Bruce Fields" , LKML , Alexander Viro , Andrew Morton , linux-fsdevel@vger.kernel.org Subject: Re: AIM7 40% regression with 2.6.26-rc1 In-Reply-To: <1210217099.3453.92.camel@ymzhang> Message-ID: References: <1210052904.3453.30.camel@ymzhang> <20080506114449.GC32591@elte.hu> <20080506120934.GH19219@parisc-linux.org> <20080506162332.GI19219@parisc-linux.org> <1210217099.3453.92.camel@ymzhang> User-Agent: Alpine 1.10 (LFD 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 Thu, 8 May 2008, Zhang, Yanmin wrote: > > On Tue, 2008-05-06 at 10:23 -0600, Matthew Wilcox wrote: > > On Tue, May 06, 2008 at 06:09:34AM -0600, Matthew Wilcox wrote: > > > So the only likely things I can see are: > > > > > > - file locks > > > - fasync > > > > I've wanted to fix file locks for a while. Here's a first attempt. > > It was done quickly, so I concede that it may well have bugs in it. > > I found (and fixed) one with LTP. > > > > It takes *no account* of nfsd, nor remote filesystems. We need to have > > a serious discussion about their requirements. > > I tested it on 8-core stoakley. aim7 result becomes 23% worse than the one of > pure 2.6.26-rc1. Ouch. That's really odd. The BKL->spinlock conversion looks really obvious, so it shouldn't be that noticeably slower. The *one* difference is that the BKL has the whole "you can take it recursively and you can sleep without dropping it because the scheduler will drop it for you" thing. The spinlock conversion changed all of that into explicit "drop and retake" locks, and maybe that causes some issues. But 23% worse? That sounds really odd/extreme. Can you do a oprofile run or something? Linus