Return-Path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:54793 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751275Ab1FIGI3 (ORCPT ); Thu, 9 Jun 2011 02:08:29 -0400 Received: by pwi15 with SMTP id 15so587944pwi.19 for ; Wed, 08 Jun 2011 23:08:29 -0700 (PDT) Message-ID: <4DF0635B.9050004@panasas.com> Date: Thu, 09 Jun 2011 02:08:27 -0400 From: Benny Halevy To: Peng Tao CC: Jim Rees , linux-nfs@vger.kernel.org, peter honeyman Subject: Re: [PATCH 87/88] Add configurable prefetch size for layoutget References: <09142112ff0115f7f22124a69ead7b9bb5e0958f.1307464382.git.rees@umich.edu> <4DEED80A.4000102@panasas.com> <20110608021852.GA20998@merit.edu> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On 2011-06-08 03:15, Peng Tao wrote: > On 6/8/11, Jim Rees wrote: >> Benny Halevy wrote: >> >> NAK. >> This affects all layout types. In particular it is undesired >> for write layouts that extend the file with the objects layout. >> The server can extend the layout segments range >> over what the client requested so why would the client >> ask for artificially large layouts? >> >> This has actually been the subject of some debate over Thursday night >> beers. The problem we're trying to solve is that the client is spending 98% >> of its time in layoutget. This patch gives us something like a 10x >> speedup. But many of us think it's not the right fix. I suggest we discuss >> next week. >> Sure. >> But note that this patch doesn't change anything unless you set the sysctl. > there is a default value of 2M. maybe we can set it to page size by > default so other layout are not affected and block layout can let > users set it by hand if they care about performance. does this make > sense? If doing it at all why use a sysctl rather than a mount option? Or maybe coding the logic for prefetching the layout iff sequential access is detected is the right thing to do. Benny >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > >