From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Dilger Subject: Re: [dm-devel] [Lsf-pc] [LSF/MM TOPIC] a few storage topics Date: Tue, 24 Jan 2012 10:01:03 -0700 Message-ID: References: <20120117213648.GA9457@quack.suse.cz> <20120118225808.GA3074@tux1.beaverton.ibm.com> <20120118232200.GA22019@quack.suse.cz> <4F1758D4.9010401@panasas.com> <20120119094637.GA23442@quack.suse.cz> <4F1BFF5F.6000502@panasas.com> <20120123161857.GC28526@quack.suse.cz> <20120123175353.GD30782@redhat.com> <20120124151504.GQ4387@shiny> <20120124165631.GA8941@infradead.org> Mime-Version: 1.0 (1.0) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: Chris Mason , Jeff Moyer , Andrea Arcangeli , Jan Kara , Boaz Harrosh , Mike Snitzer , "linux-scsi@vger.kernel.org" , "neilb@suse.de" , "dm-devel@redhat.com" , "linux-fsdevel@vger.kernel.org" , "lsf-pc@lists.linux-foundation.org" , "Darrick J.Wong" To: Christoph Hellwig Return-path: Received: from mail-vw0-f46.google.com ([209.85.212.46]:63566 "EHLO mail-vw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755925Ab2AXRAu (ORCPT ); Tue, 24 Jan 2012 12:00:50 -0500 In-Reply-To: <20120124165631.GA8941@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Cheers, Andreas On 2012-01-24, at 9:56, Christoph Hellwig wrote: > On Tue, Jan 24, 2012 at 10:15:04AM -0500, Chris Mason wrote: >> https://lkml.org/lkml/2011/12/13/326 >> >> This patch is another example, although for a slight different reason. >> I really have no idea yet what the right answer is in a generic sense, >> but you don't need a 512K request to see higher latencies from merging. > > That assumes the 512k requests is created by merging. We have enough > workloads that create large I/O from the get go, and not splitting them > and eventually merging them again would be a big win. E.g. I'm > currently looking at a distributed block device which uses internal 4MB > chunks, and increasing the maximum request size to that dramatically > increases the read performance. > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html