From owner-freebsd-arch@FreeBSD.ORG Tue Jun 3 09:27:37 2003 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9813437B401 for ; Tue, 3 Jun 2003 09:27:37 -0700 (PDT) Received: from mx.nsu.ru (mx.nsu.ru [212.192.164.5]) by mx1.FreeBSD.org (Postfix) with ESMTP id E685043F85 for ; Tue, 3 Jun 2003 09:27:35 -0700 (PDT) (envelope-from danfe@regency.nsu.ru) Received: from mail by mx.nsu.ru with drweb-scanned (Exim 3.36 #1 (Debian)) id 19NEg1-0004M7-00; Tue, 03 Jun 2003 23:30:21 +0700 Received: from regency.nsu.ru ([193.124.210.26]) by mx.nsu.ru with esmtp (Exim 3.36 #1 (Debian)) id 19NEfV-0003rx-00; Tue, 03 Jun 2003 23:29:49 +0700 Received: from regency.nsu.ru (localhost [127.0.0.1]) by regency.nsu.ru (8.12.8/8.12.8) with ESMTP id h53GQ8M5064781; Tue, 3 Jun 2003 23:26:08 +0700 (NOVST) (envelope-from danfe@regency.nsu.ru) Received: (from danfe@localhost) by regency.nsu.ru (8.12.8/8.12.8/Submit) id h53GQ8Ge064780; Tue, 3 Jun 2003 23:26:08 +0700 (NOVST) Date: Tue, 3 Jun 2003 23:26:08 +0700 From: Alexey Dokuchaev To: Matthew Dillon Message-ID: <20030603162607.GA64568@regency.nsu.ru> References: <20030602171942.GA87863@roark.gnf.org> <20030603080456.GA57773@cirb503493.alcatel.com.au> <200306031614.h53GEqkU008308@apollo.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200306031614.h53GEqkU008308@apollo.backplane.com> User-Agent: Mutt/1.4i X-Envelope-To: dillon@apollo.backplane.com, peterjeremy@optushome.com.au, arch@freebsd.org X-Bogosity: No, tests=bogofilter, spamicity=0.000000, version=0.11.1.4 X-Spam-Status: No, hits=-134.0 required=5.0 tests=BOGOFILTER_TEST_PASS,EMAIL_ATTRIBUTION,IN_REP_TO, QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, USER_AGENT_MUTT,USER_IN_WHITELIST version=2.50 X-Spam-Level: X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) cc: arch@freebsd.org Subject: Re: Making a dynamically-linked root X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 03 Jun 2003 16:27:38 -0000 On Tue, Jun 03, 2003 at 09:14:52AM -0700, Matthew Dillon wrote: > > :On Mon, Jun 02, 2003 at 02:25:43PM -0700, Matthew Dillon wrote: > :> start!). Running certain daemon startups in the background might yield > :> a significant overall improvement in startup times. > :> > :> e.g. instead of running 'sshd' you would run sshd in a subshell, aka > :> (sshd &), so the RC script can continue on with the next thing without > :> having to wait for sshd to fault-in from disk. Same goes for sendmail > :> and many other daemons. > : > :This isn't a definite win. I know in the past it used to actually > :slow things down: To take your example, having both sshd and sendmail > :attempting to fault-in from disk in parallel will thrash both the disk > :and cache far more than sshd and sendmail sequentially faulting in. A > :very large number of daemons trying to start in parallel will also > :stress the scheduler. > : > :Peter > > I'm fairly sure there isn't an issue. Both a hard drive's own > on-board cache and FreeBSD's clustering and caching code are *very* well > suited to this sort of parallel initiation. There is certainly no > scheduler issue. The key advantage here is that you are removing > serialization that would otherwise cause both cpu cycles and disk > cycles to be wasted waiting for each other. Take sendmail for example. > sendmail usually takes upwards of a second to startup due to initial > DNS lookups that it makes and other things. sshd doesn't start > instantaniously either, I think due to creating the initial > session keys. Methinks that Matt's suggestion of (sshd &) and alikes does indeed sound very cool, and at least worth of reference implementation and seeing it in action. As already mentioned by Matt, the bottleneck here is not in I/O (which is, in fact, really fast nowadays) but in either network access (in case of sendmail) or (and?) CPU-intensive routines (speaking of sshd, respectively). Just my $.02 though, as it all had been already said more or less the same way by other folks. ./danfe