From owner-freebsd-arch Fri Dec 10 18:15:50 1999 Delivered-To: freebsd-arch@freebsd.org Received: from ns1.yes.no (ns1.yes.no [195.204.136.10]) by hub.freebsd.org (Postfix) with ESMTP id 053F114E50 for ; Fri, 10 Dec 1999 18:15:45 -0800 (PST) (envelope-from eivind@bitbox.follo.net) Received: from bitbox.follo.net (bitbox.follo.net [195.204.143.218]) by ns1.yes.no (8.9.3/8.9.3) with ESMTP id DAA09081 for ; Sat, 11 Dec 1999 03:15:43 +0100 (CET) Received: (from eivind@localhost) by bitbox.follo.net (8.8.8/8.8.6) id DAA39989 for freebsd-arch@freebsd.org; Sat, 11 Dec 1999 03:15:43 +0100 (MET) Received: from picnic.mat.net (picnic.mat.net [206.246.122.133]) by hub.freebsd.org (Postfix) with ESMTP id 478BB1537D for ; Fri, 10 Dec 1999 18:15:27 -0800 (PST) (envelope-from chuckr@picnic.mat.net) Received: from localhost (chuckr@localhost [127.0.0.1]) by picnic.mat.net (8.9.3/8.9.3) with ESMTP id VAA36755; Fri, 10 Dec 1999 21:14:11 -0500 (EST) (envelope-from chuckr@picnic.mat.net) Date: Fri, 10 Dec 1999 21:14:11 -0500 (EST) From: Chuck Robey To: Nate Williams Cc: Arun Sharma , freebsd-arch@freebsd.org Subject: Re: Thread scheduling In-Reply-To: <199912110135.SAA23495@mt.sri.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Fri, 10 Dec 1999, Nate Williams wrote: > > Why is it desireable? > > It is desirable for effeciency reasons (if two threads are running on > seperate CPU's, then twice as much work will get done), as well as the > cache issues. But, is making it a requirement desirable? Not in my > book. (I may have misunderstood your 'desirable' statement previously > by reading that making assuming that you were wondering if is desirable > to make it a requirement, which is silly now that I think about it.) OK, let me state it again. I wasn't asking if it was a good thing to share out threads among multiple processors, because the advantages of using a multiple CPU system *as* a multiple CPU seem obvious enough not to need asking. I was asking to see if it would be a good thing to add a strong bias to the system, in such a way as to make the co-scheduling of threads among the different processors so that all processors that are made available to the program's threads are executing in that address space as the same moment in time. Not a guarantee, but would it be a good thing to have them "co-scheduled" (or a bias towards that likelihood). I wasn't suggesting a *single* thread across multiple processors (as I think Arun asked). Yes, that would be silly. Is what I asked also silly, as a scheduling bias, not a guarantee or a requirement? Or would it make no real difference? > > However, is it desirable to have multiple threads in a single process > executing on multiple CPUs? Of course, if the benefits don't outweight > the costs in terms of complexity and such. It's the simultaneity I am asking about. ---------------------------------------------------------------------------- Chuck Robey | Interests include C programming, Electronics, 213 Lakeside Dr. Apt. T-1 | communications, and signal processing. Greenbelt, MD 20770 | I run picnic.mat.net: FreeBSD-current(i386) and (301) 220-2114 | jaunt.mat.net : FreeBSD-current(Alpha) ---------------------------------------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message