From owner-freebsd-hackers@FreeBSD.ORG Wed Sep 20 12:50:25 2006 Return-Path: X-Original-To: freebsd-hackers@FreeBSD.ORG Delivered-To: freebsd-hackers@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 83A0816A4D4 for ; Wed, 20 Sep 2006 12:50:25 +0000 (UTC) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (lurza.secnetix.de [83.120.8.8]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4A24D43D9E for ; Wed, 20 Sep 2006 12:50:21 +0000 (GMT) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (mdazwt@localhost [127.0.0.1]) by lurza.secnetix.de (8.13.4/8.13.4) with ESMTP id k8KCo82N048911 for ; Wed, 20 Sep 2006 14:50:17 +0200 (CEST) (envelope-from oliver.fromme@secnetix.de) Received: (from olli@localhost) by lurza.secnetix.de (8.13.4/8.13.1/Submit) id k8KCo8sm048910; Wed, 20 Sep 2006 14:50:08 +0200 (CEST) (envelope-from olli) Date: Wed, 20 Sep 2006 14:50:08 +0200 (CEST) Message-Id: <200609201250.k8KCo8sm048910@lurza.secnetix.de> From: Oliver Fromme To: freebsd-hackers@FreeBSD.ORG In-Reply-To: <20060919160511.T33371@woozle.rinet.ru> X-Newsgroups: list.freebsd-hackers User-Agent: tin/1.8.0-20051224 ("Ronay") (UNIX) (FreeBSD/4.11-STABLE (i386)) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.2 (lurza.secnetix.de [127.0.0.1]); Wed, 20 Sep 2006 14:50:17 +0200 (CEST) X-Mailman-Approved-At: Wed, 20 Sep 2006 12:53:03 +0000 Cc: Subject: Re: numbers don't lie ... X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-hackers@FreeBSD.ORG List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Sep 2006 12:50:25 -0000 Dmitry Morozovsky wrote: > Oliver Fromme wrote: > > Because buildworld is I/O-bound on systems with sufficiently > > fast processors. > > > > Try putting the contents of /usr/src into a RAM disk and > > repeat the benchmark. The numbers might look a little > > different then. Of course, you should have sufficient RAM > > in the machines -- If they're going to swap to the disks, > > your benchmark won't be happy. > > > > I think putting /usr/obj onto a RAM disk is _not_ necessary > > because of soft-updates, so the processes shouldn't block > > on writes. > > My experiments show that if you have enough memory to host radmdrive for > /usr/src you'd better leave it for caching - there were no statistically > meaningful performance difference, at least on machines with 1G+ RAM. That might only be true if you have enough RAM to keep _all_ buildworld files (src, obj, toolchain) in the cache _and_ you pre-read all of /usr/src before actually starting the buildworld, so it is in the cache. If you don't have that much RAM, but enough to store /usr/src, then using a RAM disk for it is a win. Reading /usr/src from a physical disk certainly requires quite some I/O that takes more than zero time. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. "File names are infinite in length, where infinity is set to 255 characters." -- Peter Collinson, "The Unix File System"