From owner-freebsd-current Tue Apr 17 1:20: 4 2001 Delivered-To: freebsd-current@freebsd.org Received: from fw.wintelcom.net (ns1.wintelcom.net [209.1.153.20]) by hub.freebsd.org (Postfix) with ESMTP id F1CF937B43E for ; Tue, 17 Apr 2001 01:19:59 -0700 (PDT) (envelope-from bright@fw.wintelcom.net) Received: (from bright@localhost) by fw.wintelcom.net (8.10.0/8.10.0) id f3H8JvO04082; Tue, 17 Apr 2001 01:19:57 -0700 (PDT) Date: Tue, 17 Apr 2001 01:19:57 -0700 From: Alfred Perlstein To: Matt Dillon Cc: "Justin T. Gibbs" , Doug Barton , "'current@freebsd.org'" Subject: Re: FW: Filesystem gets a huge performance boost Message-ID: <20010417011957.W976@fw.wintelcom.net> References: <200104160259.f3G2xqs06321@aslan.scsiguy.com> <200104160616.f3G6GI973782@earth.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <200104160616.f3G6GI973782@earth.backplane.com>; from dillon@earth.backplane.com on Sun, Apr 15, 2001 at 11:16:18PM -0700 X-all-your-base: are belong to us. Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG * 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. -- -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message