From owner-freebsd-hackers@FreeBSD.ORG Wed Sep 20 13:56:14 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 5121B16A47B for ; Wed, 20 Sep 2006 13:56:14 +0000 (UTC) (envelope-from marck@rinet.ru) Received: from woozle.rinet.ru (woozle.rinet.ru [195.54.192.68]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3F6EF43D81 for ; Wed, 20 Sep 2006 13:56:07 +0000 (GMT) (envelope-from marck@rinet.ru) Received: from localhost (localhost [127.0.0.1]) by woozle.rinet.ru (8.13.8/8.13.6) with ESMTP id k8KDu45o073068; Wed, 20 Sep 2006 17:56:04 +0400 (MSD) (envelope-from marck@rinet.ru) Date: Wed, 20 Sep 2006 17:56:04 +0400 (MSD) From: Dmitry Morozovsky To: Eric Anderson In-Reply-To: <451140F8.9030500@centtech.com> Message-ID: <20060920175539.Q63482@woozle.rinet.ru> References: <200609201250.k8KCo8sm048910@lurza.secnetix.de> <451140F8.9030500@centtech.com> X-NCC-RegID: ru.rinet X-OpenPGP-Key-ID: 6B691B03 MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.0.2 (woozle.rinet.ru [0.0.0.0]); Wed, 20 Sep 2006 17:56:04 +0400 (MSD) Cc: freebsd-hackers@freebsd.org Subject: Re: numbers don't lie ... X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list 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 13:56:14 -0000 On Wed, 20 Sep 2006, Eric Anderson wrote: EA> > > > My experiments show that if you have enough memory to host radmdrive EA> > for > /usr/src you'd better leave it for caching - there were no EA> > statistically EA> > > meaningful performance difference, at least on machines with 1G+ RAM. EA> > EA> > That might only be true if you have enough RAM to keep EA> > _all_ buildworld files (src, obj, toolchain) in the cache EA> > _and_ you pre-read all of /usr/src before actually starting EA> > the buildworld, so it is in the cache. If you don't have EA> > that much RAM, but enough to store /usr/src, then using EA> > a RAM disk for it is a win. EA> > EA> > Reading /usr/src from a physical disk certainly requires EA> > quite some I/O that takes more than zero time. EA> EA> But, in order to populate the ram disk, you must read /usr/src also from EA> something, and that also takes time, which you should include in the full EA> scope. ... and that populates cache with src files as well ;-) Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru *** ------------------------------------------------------------------------