From owner-freebsd-hackers@FreeBSD.ORG Sun Jan 9 02:12:58 2005 Return-Path: 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 414AE16A4CE for ; Sun, 9 Jan 2005 02:12:58 +0000 (GMT) Received: from node15.coopprint.com (node15.cooperativeprinting.com [208.4.77.15]) by mx1.FreeBSD.org (Postfix) with SMTP id 43D4B43D49 for ; Sun, 9 Jan 2005 02:12:57 +0000 (GMT) (envelope-from ryans@gamersimpact.com) Received: (qmail 86034 invoked by uid 0); 9 Jan 2005 02:11:22 -0000 Received: from unknown (HELO ?192.168.0.5?) (63.231.157.250) by node15.coopprint.com with SMTP; 9 Jan 2005 02:11:22 -0000 Message-ID: <41E0933C.9010405@gamersimpact.com> Date: Sat, 08 Jan 2005 20:13:16 -0600 From: Ryan Sommers User-Agent: Mozilla Thunderbird 0.7.3 (Windows/20040803) X-Accept-Language: en-us, en MIME-Version: 1.0 To: David Malone References: <41DE4F3D.8050509@syskonnect.de> <20050107091004.83732.qmail@web52710.mail.yahoo.com> <20050107101006.GA2553@frontfree.net> <20050108135526.GQ49329@submonkey.net> <20050108202605.GA30807@walton.maths.tcd.ie> In-Reply-To: <20050108202605.GA30807@walton.maths.tcd.ie> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit cc: Charles Sprickman cc: Ceri Davies cc: tjr@freebsd.org cc: freebsd-hackers@freebsd.org Subject: Re: Benchmark: NetBSD 2.0 beats FreeBSD 5.3 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Jan 2005 02:12:58 -0000 David Malone wrote: >On Sat, Jan 08, 2005 at 01:21:14PM -0500, Charles Sprickman wrote: > > >>Any idea what type of impact this patch would have on say, a large qmail >>server that's drowning in context-switches? >> >> > >It will depend on how many processes you have running at any one >moment and how often processes are created/destroyed. From the look >of the graphs, you won't really be able to tell unless there are >significantly more than 1000 processes running at any moment. > > David. > > This could be the case. It's my understanding that Qmail spawns a new qmail-local process (specifically qmail-lspawn exec's it) for each locally delivered message. For any remote message qmail-rspawn forks a qmail-remote process. I don't believe these processes live longer than a single instance. Depending on how his mailboxes are setup this can even result in new processes being spawned. If you're running vpopmail qmail-local will pipe the message to vdelivermail. And if you're running anything like spamassassin from vpopmail (as opposed to from qmail via the QMAIL_QUEUE patch, although that will spawn a spamc of it's own) this could result in another executed process (spamc is spamd's light-weight front-end). Depending on how large and busy this qmail server is, there could definately be a large amount of time spent in process creation and teardown. I'm not sure how much Charles is familiar with the Qmail+vpopmail+spamassassin, if he is using spamassassin. But, one of the "hidden" features of using SpamAssassin and Vpopmail as installed from ports is that spamassassin is called from vpopmail. There is no run-time option (only compile time that is defaulted to on) to disable this. A lot of users don't realize this and will use the QMAIL_QUEUE patch and run spamassassin from it. This can result in scanning every email twice, which can be a costly oversight. -- Ryan Sommers ryans@gamersimpact.com