From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964790AbWFHI2b (ORCPT ); Thu, 8 Jun 2006 04:28:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932561AbWFHI2b (ORCPT ); Thu, 8 Jun 2006 04:28:31 -0400 Received: from pne-smtpout2-sn1.fre.skanova.net ([81.228.11.159]:3775 "EHLO pne-smtpout2-sn1.fre.skanova.net") by vger.kernel.org with ESMTP id S932560AbWFHI2a (ORCPT ); Thu, 8 Jun 2006 04:28:30 -0400 Date: Thu, 8 Jun 2006 10:28:02 +0200 From: Voluspa To: Fengguang Wu Cc: akpm@osdl.org, arjan@infradead.org, Valdis.Kletnieks@vt.edu, diegocg@gmail.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] readahead: initial method - expected read size - fix fastcall Message-Id: <20060608102802.6e07b148.lista1@comhem.se> In-Reply-To: <349754431.09938@ustc.edu.cn> References: <349406446.10828@ustc.edu.cn> <20060604020738.31f43cb0.akpm@osdl.org> <1149413103.3109.90.camel@laptopd505.fenrus.org> <20060605031720.0017ae5e.lista1@comhem.se> <349562623.17723@ustc.edu.cn> <20060608094356.5c1272cc.lista1@comhem.se> <349754431.09938@ustc.edu.cn> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 8 Jun 2006 16:13:52 +0800 Fengguang Wu wrote: > It's interesting that copying of sparse file is more efficient with small > readahead size :) I get the same conclusion, though with smaller differences: How on earth can you copy the file without overwriting the target /dev/null? As you saw, I could just "cat" the file. Size was: root:sleipner:~# dd if=/dev/zero of=sparse bs=1M seek=5000 count=1 1+0 records in 1+0 records out root:sleipner:~# ls -l sparse 1040 -rw-r--r-- 1 root root 5243928576 Jun 8 10:26 sparse 5.2 fake GBs... Mvh Mats Johannesson --