Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932220AbWBXAPX (ORCPT ); Thu, 23 Feb 2006 19:15:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932216AbWBXAPX (ORCPT ); Thu, 23 Feb 2006 19:15:23 -0500 Received: from smtp.osdl.org ([65.172.181.4]:50050 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932210AbWBXAPU (ORCPT ); Thu, 23 Feb 2006 19:15:20 -0500 Date: Thu, 23 Feb 2006 16:14:25 -0800 From: Andrew Morton To: john@johnmccutchan.com Cc: holt@sgi.com, linux-kernel@vger.kernel.org, rml@novell.com, arnd@arndb.de, hch@lst.de Subject: Re: udevd is killing file write performance. Message-Id: <20060223161425.4388540e.akpm@osdl.org> In-Reply-To: <1140651662.2985.2.camel@localhost.localdomain> References: <20060222134250.GE20786@lnx-holt.americas.sgi.com> <1140626903.13461.5.camel@localhost.localdomain> <20060222175030.GB30556@lnx-holt.americas.sgi.com> <1140648776.1729.5.camel@localhost.localdomain> <20060222151223.5c9061fd.akpm@osdl.org> <1140651662.2985.2.camel@localhost.localdomain> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1397 Lines: 40 John McCutchan wrote: > > ... > > > > I have a bad feeling about this one. It'd be nice to have an exact > > understanding of the problen source, but if it's just lots of traffic on > > ->d_lock we're kinda stuck. I don't expect we'll run off and RCUify > > d_parent or turn d_lock into a seq_lock or anything liek that. > > > > Then again, maybe making d_lock an rwlock _will_ help - if this workload is > > also hitting tree_lock (Robin?) and we're not seeing suckiness due to that > > then perhaps the rwlock is magically helping. > > > > > > > instead of your hack. > > > > It's not a terribly bad hack - it's just poor-man's hashing, and it's > > reasonably well-suited to the sorts of machines and workloads which we > > expect will hit this problem. > > > > If this is as good as it gets, here is a patch (totally untested). > > ... > @@ -538,7 +537,7 @@ > struct dentry *parent; > struct inode *inode; > > - if (!atomic_read (&inotify_watches)) > + if (!atomic_read (&dentry->d_sb->s_inotify_watches)) > return; > What happens here if we're watching a mountpoint - the parent is on a different fs? - 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/