From: Dave Chinner Subject: Re: [RFC] nfs: use 2*rsize readahead size Date: Wed, 24 Feb 2010 16:24:09 +1100 Message-ID: <20100224052409.GI16175@discord.disaster> References: <20100224024100.GA17048@localhost> <20100224032934.GF16175@discord.disaster> <20100224042414.GG16175@discord.disaster> <20100224044356.GA2007@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Trond Myklebust , "linux-nfs@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , Linux Memory Management List , LKML To: Wu Fengguang Return-path: Received: from bld-mail12.adl6.internode.on.net ([150.101.137.97]:43053 "EHLO mail.internode.on.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751148Ab0BXFYN (ORCPT ); Wed, 24 Feb 2010 00:24:13 -0500 In-Reply-To: <20100224044356.GA2007@localhost> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Feb 24, 2010 at 12:43:56PM +0800, Wu Fengguang wrote: > On Wed, Feb 24, 2010 at 12:24:14PM +0800, Dave Chinner wrote: > > On Wed, Feb 24, 2010 at 02:29:34PM +1100, Dave Chinner wrote: > > > That's doing a cached read out of the server cache, right? You > > > might find the results are different if the server has to read the > > > file from disk. I would expect reads from the server cache not > > > to require much readahead as there is no IO latency on the server > > > side for the readahead to hide.... > > > > FWIW, if you mount the client with "-o rsize=32k" or the server only > > supports rsize <= 32k then this will probably hurt throughput a lot > > because then readahead will be capped at 64k instead of 480k.... > > I should have mentioned that in changelog.. Hope the updated one > helps. Sorry, my fault for not reading the code correctly. Cheers, Dave. -- Dave Chinner david@fromorbit.com