From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751438AbWBVUxt (ORCPT ); Wed, 22 Feb 2006 15:53:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751446AbWBVUxt (ORCPT ); Wed, 22 Feb 2006 15:53:49 -0500 Received: from master.soleranetworks.com ([67.137.28.188]:7566 "EHLO master.soleranetworks.com") by vger.kernel.org with ESMTP id S1751438AbWBVUxs (ORCPT ); Wed, 22 Feb 2006 15:53:48 -0500 Message-ID: <43FCDC88.7090602@wolfmountaingroup.com> Date: Wed, 22 Feb 2006 14:50:00 -0700 From: "Jeff V. Merkey" User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040510 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Andrew Morton Cc: Robin Holt , john@johnmccutchan.com, linux-kernel@vger.kernel.org, rml@novell.com, arnd@arndb.de, hch@lst.de Subject: Re: udevd is killing file write performance. References: <20060222134250.GE20786@lnx-holt.americas.sgi.com> <1140626903.13461.5.camel@localhost.localdomain> <20060222175030.GB30556@lnx-holt.americas.sgi.com> <20060222120547.2ae23a16.akpm@osdl.org> In-Reply-To: <20060222120547.2ae23a16.akpm@osdl.org> Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: >Robin Holt wrote: > > >>Let me reiterate, I know _VERY_ little about filesystems. Can the >> dentry->d_lock be changed to a read/write lock? >> >> > >Well, it could, but I suspect that won't help - the hold times in there >will be very short so the problem is more likely acquisition frequency. > >However it's a bit strange that this function is the bottleneck. If their >workload is doing large numbers of reads or writes from large numbers of >processes against the same file then they should be hitting heavy >contention on other locks, such as i_sem and/or tree_lock and/or lru_lock >and others. > >Can you tell us more about the kernel-visible behaviour of this app? > > I have also seen this problem, and it's hard to reproduce. What you will see is udev getting spawned multiple times as reported by top. I have found its related to intermittent failures of the hard drive and the hotpluger for some reason invoking udev multiple times in response to this. I saw it on a Compaq laptop right before my hard drive croaked, and it seems BIOS specific as well, since I have never seen it or been able to reproduce it reliably. Jeff >- >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/ > > >