From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757568Ab2AKOMG (ORCPT ); Wed, 11 Jan 2012 09:12:06 -0500 Received: from Mycroft.westnet.com ([216.187.52.7]:38254 "EHLO mycroft.westnet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757510Ab2AKOMB (ORCPT ); Wed, 11 Jan 2012 09:12:01 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <20237.39051.575883.450826@quad.stoffel.home> Date: Wed, 11 Jan 2012 09:11:23 -0500 From: "John Stoffel" To: KOSAKI Motohiro Cc: Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Mel Gorman , Johannes Weiner Subject: Re: [PATCH -mm] make swapin readahead skip over holes In-Reply-To: References: <20120109181023.7c81d0be@annuminas.surriel.com> <4F0B7D1F.7040802@gmail.com> <4F0BABE0.8080107@redhat.com> X-Mailer: VM 8.1.1 under 23.2.1 (x86_64-pc-linux-gnu) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>>>> "KOSAKI" == KOSAKI Motohiro writes: >> Also, I doubt current swap_cluster default is best value on nowadays. KOSAKI> I meant, current average hdd spec is, KOSAKI> - average seek time: 8.5ms KOSAKI> - sequential access performance: about 60MB/sec 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. John