From owner-freebsd-current@FreeBSD.ORG Sat Dec 13 02:27:25 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5AB6A16A4CE for ; Sat, 13 Dec 2003 02:27:25 -0800 (PST) Received: from sccrmhc12.comcast.net (sccrmhc12.comcast.net [204.127.202.56]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5266343D1D for ; Sat, 13 Dec 2003 02:27:23 -0800 (PST) (envelope-from adam@migus.org) Received: from ludo.migus.org ([68.55.80.136]) by comcast.net (sccrmhc12) with ESMTP id <200312131027220120001smqe>; Sat, 13 Dec 2003 10:27:22 +0000 Received: from localhost (localhost [127.0.0.1]) by localhost (Postfix) with ESMTP id 79700A103B; Sat, 13 Dec 2003 05:27:22 -0500 (EST) Received: from ludo.migus.org ([127.0.0.1]) by localhost (ludo.migus.org [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 91021-07; Sat, 13 Dec 2003 05:27:19 -0500 (EST) Received: from migus.org (ganyopa.migus.org [192.168.4.2]) by ludo.migus.org (Postfix) with ESMTP id 6BAA1A103A; Sat, 13 Dec 2003 05:27:19 -0500 (EST) Message-ID: <3FDAE988.9070103@migus.org> Date: Sat, 13 Dec 2003 05:27:20 -0500 From: "Adam C. Migus" Organization: Migus Dot Org User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.5) Gecko/20031007 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Colin Percival References: <5.0.2.1.1.20031130190339.0322e0b8@popserver.sfu.ca> In-Reply-To: <5.0.2.1.1.20031130190339.0322e0b8@popserver.sfu.ca> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at migus.org cc: freebsd-current@freebsd.org Subject: Re: user:sys time ratio X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 13 Dec 2003 10:27:25 -0000 Colin Percival wrote: > Robert Watson suggested that I compare performance from UP and SMP > kernels: > > # /usr/bin/time -hl sh -c 'make -s buildworld 2>&1' > /dev/null > Real User Sys > UP kernel 38m33.29s 27m10.09s 10m59.15s > (retest) 38m33.18s 27m04.40s 11m05.73s > SMP w/o HTT 41m01.54s 27m10.27s 13m29.82s > (retest) 39m47.50s 27m08.05s 12m12.20s > SMP w/HTT 42m17.16s 28m12.82s 14m04.93s > (retest) 44m09.61s 28m15.31s 15m44.86s > > That enabling HTT degrades performance is not surprising, since I'm > not passing the -j option to make; but a 5% performance delta between > UP and SMP kernels is rather surprising (to me, at least), and the > fact that the system time varies so much on the SMP kernel also seems > peculiar. > Is this normal? > > Colin Percival > Colin, Sorry for the long delay. A bit behind on this list. I would suggest seeing what happens to those number when you _do_ use -j. Like phk said the sys/user ratio can vary quite a bit and it does so within one buildworld due to the way the build system works. If you watch the build as it's running you'll see the ratio vary greatly. To add to what phk said, with buildworld, as well as what you're doing your hardware matters for the magic number for peak utilization. My guess for an 'optimal' build based on your hardware description would be -j3 based on past experience. Perhaps -j4 with the new features but that's even more of a guess. FWIW staggering builds helps a lot if you just want to make sure you cranking your hardware since the variation is mainly due to many io-bound or cpu-bound things happening at once. But I guess most people don't build more than one world at the same time. :-) Adam