From owner-freebsd-arch@FreeBSD.ORG Tue Jun 3 09:14:55 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 3D1F837B401 for ; Tue, 3 Jun 2003 09:14:55 -0700 (PDT) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id B534E43F93 for ; Tue, 3 Jun 2003 09:14:52 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (localhost [127.0.0.1]) by apollo.backplane.com (8.12.9/8.12.6) with ESMTP id h53GEqVI008309; Tue, 3 Jun 2003 09:14:52 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.12.9/8.12.6/Submit) id h53GEqkU008308; Tue, 3 Jun 2003 09:14:52 -0700 (PDT) Date: Tue, 3 Jun 2003 09:14:52 -0700 (PDT) From: Matthew Dillon Message-Id: <200306031614.h53GEqkU008308@apollo.backplane.com> To: Peter Jeremy References: <20030602171942.GA87863@roark.gnf.org> <20030603080456.GA57773@cirb503493.alcatel.com.au> 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 16:14:55 -0000 :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. -Matt Matthew Dillon