From owner-freebsd-hackers Sun Dec 20 14:29:00 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id OAA28996 for freebsd-hackers-outgoing; Sun, 20 Dec 1998 14:29:00 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from caladan.tdx.co.uk (caladan.tdx.co.uk [195.188.177.4]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id OAA28991 for ; Sun, 20 Dec 1998 14:28:58 -0800 (PST) (envelope-from kpielorz@tdx.co.uk) Received: from localhost (kpielorz@localhost) by caladan.tdx.co.uk (8.9.1a/8.9.1) with ESMTP id WAA27573; Sun, 20 Dec 1998 22:28:20 GMT Date: Sun, 20 Dec 1998 22:28:20 +0000 (GMT) From: Karl Pielorz To: Alfred Perlstein cc: hackers@FreeBSD.ORG Subject: Re: question about re-entrancy. In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Sun, 20 Dec 1998, Alfred Perlstein wrote: > > I'm a bit confused. I've been watching the discussions going on about > SMP. The issue of kernel re-entrancy has been brought up many times. > > So here's the question: > > I thought the kernel was re-entrant, when a process makes a syscall it's > thread of execution enters the kernel where its arguments are validated > and careful checks are done to ensure security then the syscall is done. Hmmm... AFAIK the FreeBSD kernel at the moment is like the Linux one certainly used to be (at last week ;-) - i.e. under SMP the kernel has a big lock around it - so that only 1 CPU can actively be in the kernel at a time... I beleive it's also the goal to make the granularity on this 'big lock' ever finer as more code get's developed... > Or are the spl calls simply there to diable interupts? but that brings me > back to the question about "well how do nfsd and nfsiod do it?" Hmmm... At the risk of being totally wrong - I thought that's all they did?... > Mike, Terry, Matt, John? Uhgh, yes - good idea, I'll leave it for someone who knows what their talking about to give the 'right' answer :-) - Some of the details for the current SMP implementaion were hanging around on www.freebsd.org a while ago... -Kp To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message