Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 9 Jan 2002 13:20:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 9 Jan 2002 13:20:04 -0500 Received: from x35.xmailserver.org ([208.129.208.51]:48397 "EHLO x35.xmailserver.org") by vger.kernel.org with ESMTP id ; Wed, 9 Jan 2002 13:18:59 -0500 Date: Wed, 9 Jan 2002 10:24:14 -0800 (PST) From: Davide Libenzi X-X-Sender: davide@blue1.dev.mcafeelabs.com To: Ingo Molnar cc: Mike Kravetz , Linus Torvalds , lkml , george anzinger Subject: Re: [patch] O(1) scheduler, -D1, 2.5.2-pre9, 2.4.17 In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 9 Jan 2002, Ingo Molnar wrote: > > On Tue, 8 Jan 2002, Davide Libenzi wrote: > > > Mike can you try the patch listed below on custom pre-10 ? > > I've got 30-70% better performances with the chat_s/c test. > > i've compared this patch of yours (which changes the way interactivity is > detected and timeslices are distributed), to 2.5.2-pre10-vanilla on a > 2-way 466 MHz Celeron box: > > davide-patch-2.5.2-pre10 running at default priority: > > # ./chat_s 127.0.0.1 > # ./chat_c 127.0.0.1 10 1000 > > Average throughput : 123103 messages per second > Average throughput : 105122 messages per second > Average throughput : 112901 messages per second > > [ system is *unusable* interactively, during the whole test. ] > > davide-patch-2.5.2-pre10 running at nice level 19: > > # nice -n 19 ./chat_s 127.0.0.1 > # nice -n 19 ./chat_c 127.0.0.1 10 1000 > > Average throughput : 109337 messages per second > Average throughput : 122077 messages per second > Average throughput : 105296 messages per second > > [ system is *unusable* interactively, despite renicing. ] > > 2.5.2-pre10-vanilla running the test at the default priority level: > > # ./chat_s 127.0.0.1 > # ./chat_c 127.0.0.1 10 1000 > > Average throughput : 124676 messages per second > Average throughput : 102244 messages per second > Average throughput : 115841 messages per second > > [ system is unresponsive at the start of the test, but > once the 2.5.2-pre10 load-estimator establishes which task is > interactive and which one is not, the system becomes usable. > Load can be felt and there are frequent delays in commands. ] > > 2.5.2-pre10-vanilla running at nice level 19: > > # nice -n 19 ./chat_s 127.0.0.1 > # nice -n 19 ./chat_c 127.0.0.1 10 1000 > > Average throughput : 214626 messages per second > Average throughput : 220876 messages per second > Average throughput : 225529 messages per second > > [ system is usable from the beginning - nice levels are working as > expected. Load can be felt while executing shell commands, but the > system is usable. Load cannot be felt in truly interactive > applications like editors. > > Summary of throughput results: 2.5.2-pre10-vanilla is equivalent > throughput-wise in the test with your patched kernel, but the vanilla > kernel is about 100% faster than your patched kernel when running reniced. > > but the interactivity observations are the real showstoppers in my > opinion. With your patch applied the system became *unbearably* slow > during the test. Ingo, this is not the picture that i've got from my machine. ------------------------------------------------------------------- AMD Athlon 1GHz 256 Mb RAM, swap_cnt patch : # nice -n 19 chat_s 127.0.0.1 & # nice -n 19 chat_c 127.0.0.1 20 1000 125236 123988 128048 with : r b w swpd free buff cache si so bi bo in cs us sy id 198 0 0 1476 28996 8024 89408 0 0 0 108 812 19424 12 87 1 216 0 1 1476 32388 8024 89412 0 0 0 0 523 56344 9 91 0 134 0 1 1476 32812 8024 89412 0 0 0 0 578 32374 9 91 0 96 1 1 1476 33540 8024 89412 0 0 0 0 114 7910 13 87 0 81 0 0 1476 35412 8024 89420 0 0 0 12 657 54034 12 88 0 pre-10 : 135684 127456 132420 the niced -20 vmstat has not been run for the whole test time and the system seemed quite bad ( personal feeling, not for the whole test time but for 1-2 sec spots ) compared with the previous test. The whole point Ingo is that during the test we've had 200 tasks on the run queue with a cs 8000..50000 !!? AMD Athlon 1GHz, swap_cnt patch : # chat_s 127.0.0.1 & # chat_c 127.0.0.1 20 1000 118386 114464 117972 pre-10 : 90066 88234 92612 I was not able to identify any interactive feel difference here. ---------------------------------------------------------------------- Today i'll try the same on both my dual cpu system ( PIII 733 and PIII 1GHz ) I really fail to understand why you're asking everyone to run your test reniced ?!? > - your patch in essence makes the scheduler ignore things like nice > level +19. We *used to* ignore nice levels, but with the new load > estimator this has changed, and personally i dont think i want to go > back to the old behavior. Ingo for the duration of the test the `nice -n 20 vmstat -n 1` never run for about the 20 seconds. With the swap_cnt correction it ran for 5-6 times. > - the system i tested has a more than twice as slow CPU as yours. So i'd > suggest for you to repeat those exact tests but increase the number of > 'rooms' to something like 40 (i know you tried 20 rooms, i dont think > it's enough), and increase the number of messages sent, from 1000 to > 5000 or something like that. Ingo, with 20 rooms my system was loaded with more than 200 tasks on the run queue and was switching at 50000 times/sec. Don't you think that it's enough for a single cpu system ??!! > your patch indeed decreases the load estimation and interactivity > detection overhead and code complexity - but as the above tests have > shown, at the price of interactivity, and in some cases even at the price > of throughput. Ingo i tried to be the more impartial as possible and during the test i was not able to identify any difference in system usability. As i wrote you in private, the only spot i've had of system unusability was running with stock pre10 ( but this could be happened occasionally ). - Davide - 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/