From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f48.google.com (mail-wg0-f48.google.com [74.125.82.48]) by kanga.kvack.org (Postfix) with ESMTP id 2B3096B0031 for ; Fri, 24 Jan 2014 06:09:32 -0500 (EST) Received: by mail-wg0-f48.google.com with SMTP id x13so2815620wgg.27 for ; Fri, 24 Jan 2014 03:09:31 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id ka5si346332wjc.46.2014.01.24.03.09.31 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Fri, 24 Jan 2014 03:09:31 -0800 (PST) Date: Fri, 24 Jan 2014 11:09:28 +0000 From: Mel Gorman Subject: Re: [Lsf-pc] [LSF/MM TOPIC] really large storage sectors - going beyond 4096 bytes Message-ID: <20140124110928.GR4963@suse.de> References: <20131220093022.GV11295@suse.de> <52DF353D.6050300@redhat.com> <20140122093435.GS4963@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Ric Wheeler , linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, lsf-pc@lists.linux-foundation.org, linux-kernel@vger.kernel.org On Thu, Jan 23, 2014 at 02:47:10PM -0600, Christoph Lameter wrote: > On Wed, 22 Jan 2014, Mel Gorman wrote: > > > Large block support was proposed years ago by Christoph Lameter > > (http://lwn.net/Articles/232757/). I think I was just getting started > > in the community at the time so I do not recall any of the details. I do > > believe it motivated an alternative by Nick Piggin called fsblock though > > (http://lwn.net/Articles/321390/). At the very least it would be nice to > > know why neither were never merged for those of us that were not around > > at the time and who may not have the chance to dive through mailing list > > archives between now and March. > > It was rejected first because of the necessity of higher order page > allocations. Nick and I then added ways to virtually map higher order > pages if the page allocator could no longe provide those. > That'd be okish for 64-bit at least although it would show up as degraded performance in some cases when virtually contiguous buffers were used. Aside from the higher setup, access costs and teardown costs of a virtual contiguous buffer, the underlying storage would no longer gets a single buffer as part of the IO request. Would that not offset many of the advantages? -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org