From owner-freebsd-smp Sun Dec 15 19:44:16 1996 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.4/8.8.4) id TAA04648 for smp-outgoing; Sun, 15 Dec 1996 19:44:16 -0800 (PST) Received: from po1.glue.umd.edu (root@po1.glue.umd.edu [129.2.128.44]) by freefall.freebsd.org (8.8.4/8.8.4) with ESMTP id TAA04643 for ; Sun, 15 Dec 1996 19:44:13 -0800 (PST) Received: from gilligan.eng.umd.edu (gilligan.eng.umd.edu [129.2.103.21]) by po1.glue.umd.edu (8.8.3/8.7.3) with ESMTP id WAA10725; Sun, 15 Dec 1996 22:44:10 -0500 (EST) Received: from localhost (chuckr@localhost) by gilligan.eng.umd.edu (8.8.3/8.7.3) with SMTP id WAA13626; Sun, 15 Dec 1996 22:44:09 -0500 (EST) X-Authentication-Warning: gilligan.eng.umd.edu: chuckr owned process doing -bs Date: Sun, 15 Dec 1996 22:44:09 -0500 (EST) From: Chuck Robey X-Sender: chuckr@gilligan.eng.umd.edu To: Michael Hancock cc: smp@freebsd.org Subject: Re: General SMP Design In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-smp@freebsd.org X-Loop: FreeBSD.org Precedence: bulk On Mon, 16 Dec 1996, Michael Hancock wrote: > On Sun, 15 Dec 1996, Chuck Robey wrote: > > > On Mon, 16 Dec 1996, Michael Hancock wrote: > > > > > http://www-dsg.stanford.edu/papers/non-blocking-osdi/index.html > > > > > > We have many examples of type-stable memory management in our code. i.e. > > > a vnode is always an instance of a vnode, it can be a on a free list. It > > > doesn't change it's type. The zone allocator is a good thing. > > > > I read that, but I don't clearly see why TSM was required. Not talking > > about the benefits, but why it's required by NBS. Are you clearer, and > > could you explain it without too much verbage (I don't want to make > > everyone read a thesis here 8-> ). > > I'm still reading it myself, but I think it is because you don't want a > data structure to change "underneath" you while other higher priority > processes take over your lock and you retry later on. Type-stable memory > simplifies implementation. > > SMP is complex, which why I think people should read good background > material. Good infrastructure design can reduce complexity and improve > performance at the same time. > > "UNIX Systems for modern architectures" by Schimmel and "UNIX Internals: > the new frontiers" by Vahalia have the traditional approaches. When > reading that stuff, you can't help wondering if there's a better way to do > solve priority inversion, deadlocks, and all those other SMP problems. > > I don't know if NBS is a real silver bullet, but it's cool that find > someone out there thinking about alternatives to what we know today. I thought the URL you posted above was the thesis (which I'd already downloaded and read) but what you gave is an expanded form of it, so I have to study it and see if maybe the TSM concept is explained more fully. Thanks. > > Regards, > > > Mike Hancock > > ----------------------------+----------------------------------------------- Chuck Robey | Interests include any kind of voice or data chuckr@eng.umd.edu | communications topic, C programming, and Unix. 9120 Edmonston Ct #302 | Greenbelt, MD 20770 | I run Journey2 and picnic, both FreeBSD (301) 220-2114 | version 3.0 current -- and great FUN! ----------------------------+-----------------------------------------------