From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx206.postini.com [74.125.245.206]) by kanga.kvack.org (Postfix) with SMTP id 77E706B006E for ; Wed, 11 Jan 2012 14:17:03 -0500 (EST) Date: Wed, 11 Jan 2012 13:17:00 -0600 (CST) From: Christoph Lameter Subject: Re: [PATCH -mm] make swapin readahead skip over holes In-Reply-To: <20237.39051.575883.450826@quad.stoffel.home> Message-ID: References: <20120109181023.7c81d0be@annuminas.surriel.com> <4F0B7D1F.7040802@gmail.com> <4F0BABE0.8080107@redhat.com> <20237.39051.575883.450826@quad.stoffel.home> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: John Stoffel Cc: KOSAKI Motohiro , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Mel Gorman , Johannes Weiner On Wed, 11 Jan 2012, John Stoffel wrote: > KOSAKI> so, we can eat free lunch up to 7MB ~= 60(MB/sec) * 1000 / 8.5(ms). > > What if the disk is busy doing other writeout or readin during this > time? You can't assume you have the full disk bandwidth available, > esp when you hit a swap storm like this. The assumptions by Kosaki are quite conservative. What if one did not get a disk from the garbage heap but instead has a state of the art storage cluster or simply an SSD (in particular relevant now since HDs are in short supply given the situation in Asia)? -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org