From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263618AbUACR4a (ORCPT ); Sat, 3 Jan 2004 12:56:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263620AbUACR4a (ORCPT ); Sat, 3 Jan 2004 12:56:30 -0500 Received: from host-64-65-253-246.alb.choiceone.net ([64.65.253.246]:37267 "EHLO gaimboi.tmr.com") by vger.kernel.org with ESMTP id S263618AbUACR41 (ORCPT ); Sat, 3 Jan 2004 12:56:27 -0500 Message-ID: <3FF70241.1030307@tmr.com> Date: Sat, 03 Jan 2004 12:56:17 -0500 From: Bill Davidsen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6b) Gecko/20031208 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Con Kolivas CC: linux kernel mailing list , Nick Piggin , Ingo Molnar Subject: Re: HT schedulers' performance on single HT processor References: <200312130157.36843.kernel@kolivas.org> In-Reply-To: <200312130157.36843.kernel@kolivas.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Con Kolivas wrote: > I set out to find how the hyper-thread schedulers would affect the all > important kernel compile benchmark on machines that most of us are likely to > encounter soon. The single processor HT machine. > > Usual benchmark precautions taken; best of five runs (curiously the fastest > was almost always the second run). Although for confirmation I really did > this twice. > > Tested a kernel compile with make vmlinux, make -j2 and make -j8. > > make vmlinux - tests to ensure the sequential single threaded make doesn't > suffer as a result of these tweaks > > make -j2 vmlinux - tests to see how well wasted idle time is avoided > > make -j8 vmlinux - maximum throughput test (4x nr_cpus seems to be ceiling for > this). > > Hardware: P4 HT 3.066 > > Legend: > UP - Uniprocessor 2.6.0-test11 kernel > SMP - SMP kernel > C1 - With Ingo's C1 hyperthread patch > w26 - With Nick's w26 sched-rollup (hyperthread included) > > make vmlinux > kernel time > UP 65.96 > SMP 65.80 > C1 66.54 > w26 66.25 > > I was concerned this might happen and indeed the sequential single threaded > compile is slightly worse on both HT schedulers. (1) > > make -j2 vmlinux > kernel time > UP 65.17 > SMP 57.77 > C1 66.01 > w26 57.94 > > Shows the smp kernel nicely utilises HT whereas the UP kernel doesn't. The C1 > result was very repeatable and I was unable to get it lower than this.(2) > > make -j8 vmlinux > kernel time > UP 65.00 > SMP 57.85 > C1 58.25 > w26 57.94 If you could make one more test, do the compile with -pipe set in the top level Makefile. I don't have play access to a HT uni, the only machines available to me at the moment are SMP and production at that. I did try it just for grins on a non-HT uni and saw this: opt real user sys idle -j1 406.2 308.1 19.0 79.1 -j1 -pipe 398.6 308.2 19.0 71.4 -j3 391.6 308.3 19.0 64.3 -j3 -pipe 388.7 308.4 19.0 61.3 P4-2.4MHz, 256MB, compiling 2.5.47-ac6 with just "make." Using -pipe *may* allow both siblings to cooperate better. I assume that CPU affinity should apply to all siblings in a package? -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979