From owner-freebsd-current Tue Apr 17 17: 2:18 2001 Delivered-To: freebsd-current@freebsd.org Received: from wantadilla.lemis.com (wantadilla.lemis.com [192.109.197.80]) by hub.freebsd.org (Postfix) with ESMTP id 88B4637B424 for ; Tue, 17 Apr 2001 17:02:14 -0700 (PDT) (envelope-from grog@lemis.com) Received: by wantadilla.lemis.com (Postfix, from userid 1004) id 9D08F6ACB8; Wed, 18 Apr 2001 09:32:12 +0930 (CST) Date: Wed, 18 Apr 2001 09:32:12 +0930 From: Greg Lehey To: Alfred Perlstein Cc: Matt Dillon , "Justin T. Gibbs" , Doug Barton , "current @ freebsd . org" Subject: Kernel preemption, yes or no? (was: Filesystem gets a huge performance boost) Message-ID: <20010418093212.A80877@wantadilla.lemis.com> References: <200104160259.f3G2xqs06321@aslan.scsiguy.com> <200104160616.f3G6GI973782@earth.backplane.com> <20010417011957.W976@fw.wintelcom.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20010417011957.W976@fw.wintelcom.net>; from bright@wintelcom.net on Tue, Apr 17, 2001 at 01:19:57AM -0700 Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-418-838-708 WWW-Home-Page: http://www.lemis.com/~grog X-PGP-Fingerprint: 6B 7B C3 8C 61 CD 54 AF 13 24 52 F8 6D A4 95 EF Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tuesday, 17 April 2001 at 1:19:57 -0700, Alfred Perlstein wrote: > * Matt Dillon [010415 23:16] wrote: >> >> For example, all this work on a preemptive >> kernel is just insane. Our entire kernel is built on the concept of >> not being preemptable except by interrupts. We virtually guarentee >> years of instability and bugs leaking out of the woodwork by trying to >> make it preemptable, and the performance gain we get for that pain >> is going to be zilch. Nada. Nothing. > > Pre-emption is mearly a side effect of a mutex'd kernel. > > The actual gains are in terms of parallel execution internally. > Meaning if we happen to copyin() a 4 meg buffer we can allow more > than one process to be completing some sort of work inside the > kernel other than spinning on the giant lock. *sigh* Couldn't you have changed the subject line when discussing something of this importance? Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message