From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: Massive slowdown when re-querying large nfs dir Date: Tue, 6 Nov 2007 22:19:39 -0800 Message-ID: <20071106221939.cfa79f9e.akpm@linux-foundation.org> References: <200711050758.38090.a1426z@gawab.com> <200711061428.11453.a1426z@gawab.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Neil Brown To: Al Boldi Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:59953 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755884AbXKGGTs (ORCPT ); Wed, 7 Nov 2007 01:19:48 -0500 In-Reply-To: <200711061428.11453.a1426z@gawab.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org > On Tue, 6 Nov 2007 14:28:11 +0300 Al Boldi wrote: > Al Boldi wrote: > > There is a massive (3-18x) slowdown when re-querying a large nfs dir (2k+ > > entries) using a simple ls -l. > > > > On 2.6.23 client and server running userland rpc.nfs.V2: > > first try: time -p ls -l <2k+ entry dir> in ~2.5sec > > more tries: time -p ls -l <2k+ entry dir> in ~8sec > > > > first try: time -p ls -l <5k+ entry dir> in ~9sec > > more tries: time -p ls -l <5k+ entry dir> in ~180sec > > > > On 2.6.23 client and 2.4.31 server running userland rpc.nfs.V2: > > first try: time -p ls -l <2k+ entry dir> in ~2.5sec > > more tries: time -p ls -l <2k+ entry dir> in ~7sec > > > > first try: time -p ls -l <5k+ entry dir> in ~8sec > > more tries: time -p ls -l <5k+ entry dir> in ~43sec > > > > Remounting the nfs-dir on the client resets the problem. > > > > Any ideas? > > Ok, I played some more with this, and it turns out that nfsV3 is a lot > faster. But, this does not explain why the 2.4.31 kernel is still over > 4-times faster than 2.6.23. > > Can anybody explain what's going on? > Sure, Neil can! ;)