Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 21 Feb 2003 00:16:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 21 Feb 2003 00:16:06 -0500 Received: from packet.digeo.com ([12.110.80.53]:38075 "EHLO packet.digeo.com") by vger.kernel.org with ESMTP id ; Fri, 21 Feb 2003 00:15:51 -0500 Date: Thu, 20 Feb 2003 21:27:30 -0800 From: Andrew Morton To: linux-kernel@vger.kernel.org Subject: iosched: impact of streaming write on read-many-files Message-Id: <20030220212730.29de4171.akpm@digeo.com> In-Reply-To: <20030220212304.4712fee9.akpm@digeo.com> References: <20030220212304.4712fee9.akpm@digeo.com> X-Mailer: Sylpheed version 0.8.9 (GTK+ 1.2.10; i586-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 21 Feb 2003 05:25:51.0829 (UTC) FILETIME=[B308D850:01C2D969] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3149 Lines: 68 Here we look at what affect a large streaming write has upon an operation which reads many small files from the same disk. A single streaming write was set up with: while true do dd if=/dev/zero of=foo bs=1M count=512 conv=notrunc done and we measure how long it takes to read all the files from a 2.4.19 kernel tree off the same disk with time (find kernel-tree -type f | xargs cat > /dev/null) As a reference, the time to read the kernel tree with no competing I/O is 7.9 seconds. 2.4.21-pre4: Don't know. I killed it after 15 minutes. Judging from the vmstat output it would have taken many hours. 2.5.61+hacks: 7 minutes 27 seconds r b swpd free buff cache si so bi bo in cs us sy id wa 0 8 0 2188 1200 226692 0 0 852 17664 1204 253 0 3 0 97 0 8 0 4148 1212 224804 0 0 1940 16208 1187 245 0 2 0 98 0 7 0 4260 1128 224756 0 0 324 20228 1226 298 0 3 0 97 0 8 0 4204 1048 224944 0 0 500 20856 1227 313 0 3 0 97 1 7 0 2300 1040 226840 0 0 348 20272 1227 313 0 3 0 97 0 8 0 4204 1044 224952 0 0 212 21564 1230 320 0 3 0 97 2.5.61+CFQ: 9 minutes 55 seconds r b swpd free buff cache si so bi bo in cs us sy id wa 1 2 0 4308 1028 224660 0 0 180 38368 1250 357 0 3 6 91 0 4 0 2180 1020 226852 0 0 324 25196 1266 408 0 4 1 95 0 4 0 2236 1016 226744 0 0 252 26948 1276 449 0 4 2 93 0 4 0 4196 1020 224816 0 0 380 23204 1250 454 0 3 4 93 0 3 0 4356 1036 224632 0 0 2616 25824 1271 490 0 4 0 96 0 4 0 4140 968 224996 0 0 496 29416 1304 609 0 4 0 96 0 4 0 2180 948 226972 0 0 352 29364 1300 688 0 5 0 95 0 3 0 4364 928 224796 0 0 344 22100 1281 656 0 4 22 74 (CFQ had a strange 20-second pause in which it performed no reads at all) (And a later 4-second one) (then 10 seconds..) 2.5.61+AS: 17 seconds r b swpd free buff cache si so bi bo in cs us sy id wa 0 6 0 2280 2716 226112 0 0 0 22388 1205 151 0 3 0 97 0 6 0 4296 2596 224168 0 0 0 21968 1213 148 0 3 0 97 1 6 0 3872 2516 224408 0 0 296 19552 1223 249 0 3 0 97 0 9 0 2176 2584 225324 0 0 5112 14588 1573 1424 0 5 0 94 0 8 0 3364 2668 223116 0 0 17512 8500 3059 6065 0 8 0 92 1 8 0 4156 2708 221340 0 0 12812 9560 2695 4863 0 9 0 91 0 8 0 3740 2956 221188 0 0 17216 7200 2406 4045 0 6 0 94 0 9 0 3828 2668 221192 0 0 9712 8972 1615 1540 0 5 0 94 1 6 0 2060 2924 222272 0 0 8428 17784 1713 1718 0 5 0 95 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/