From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: AIM7 40% regression with 2.6.26-rc1 Date: Tue, 6 May 2008 10:21:53 -0700 Message-ID: <20080506102153.5484c6ac.akpm@linux-foundation.org> References: <1210052904.3453.30.camel@ymzhang> <20080506114449.GC32591@elte.hu> <20080506120934.GH19219@parisc-linux.org> <20080506162332.GI19219@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Ingo Molnar , "J. Bruce Fields" , "Zhang, Yanmin" , LKML , Alexander Viro , Linus Torvalds , linux-fsdevel@vger.kernel.org To: Matthew Wilcox Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:38139 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755906AbYEFRWl (ORCPT ); Tue, 6 May 2008 13:22:41 -0400 In-Reply-To: <20080506162332.GI19219@parisc-linux.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, 6 May 2008 10:23:32 -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. Do we actually know that the locks code is implicated in this regression? I'd initially thought "lseek" but afaict tmpfs doesn't hit default_llseek() or remote_llseek(). tmpfs tends to do weird stuff - it would be interesting to know if the regression is also present on ramfs or ext2/ext3/xfs/etc. It would be interesting to see if the context switch rate has increased. Finally: how come we regressed by swapping the semaphore implementation anyway? We went from one sleeping lock implementation to another - I'd have expected performance to be pretty much the same. down(), down_interruptible() and down_try() should use spin_lock_irq(), not irqsave. up() seems to be doing wake-one, FIFO which is nice. Did the implementation which we just removed also do that? Was it perhaps accidentally doing LIFO or something like that?