Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261914AbVC3OvM (ORCPT ); Wed, 30 Mar 2005 09:51:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261920AbVC3OvM (ORCPT ); Wed, 30 Mar 2005 09:51:12 -0500 Received: from pat.uio.no ([129.240.130.16]:31206 "EHLO pat.uio.no") by vger.kernel.org with ESMTP id S261914AbVC3OvI (ORCPT ); Wed, 30 Mar 2005 09:51:08 -0500 Subject: Re: NFS client latencies From: Trond Myklebust To: Lee Revell Cc: Ingo Molnar , linux-kernel In-Reply-To: <1112192778.17365.2.camel@mindpipe> References: <1112137487.5386.33.camel@mindpipe> <1112138283.11346.2.camel@lade.trondhjem.org> <1112192778.17365.2.camel@mindpipe> Content-Type: text/plain Date: Wed, 30 Mar 2005 09:50:56 -0500 Message-Id: <1112194256.10634.35.camel@lade.trondhjem.org> Mime-Version: 1.0 X-Mailer: Evolution 2.0.4 Content-Transfer-Encoding: 7bit X-UiO-Spam-info: not spam, SpamAssassin (score=-3.407, required 12, autolearn=disabled, AWL 1.54, FORGED_RCVD_HELO 0.05, UIO_MAIL_IS_INTERNAL -5.00) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1176 Lines: 31 on den 30.03.2005 Klokka 09:26 (-0500) skreiv Lee Revell: > On Tue, 2005-03-29 at 18:18 -0500, Trond Myklebust wrote: > > ty den 29.03.2005 Klokka 18:04 (-0500) skreiv Lee Revell: > > > I am seeing long latencies in the NFS client code. Attached is a ~1.9 > > > ms latency trace. > > > > What kind of workload are you using to produce these numbers? > > > > Here is the other long latency I am seeing in the NFS client. I posted > this before, but did not cc: the correct people. > > It looks like nfs_wait_on_requests is doing thousands of > radix_tree_gang_lookups while holding some lock. That's normal and cannot be avoided: when writing, we have to look for the existence of old nfs_page requests. The reason is that if one does exist, we must either coalesce our new dirty area into it or if we can't, we must flush the old request out to the server. Cheers, Trond -- Trond Myklebust - 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/