From owner-freebsd-arch Sun Dec 12 20:27:54 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 A797014ED4 for ; Sun, 12 Dec 1999 20:27:40 -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 FAA02695 for ; Mon, 13 Dec 1999 05:27:38 +0100 (CET) Received: (from eivind@localhost) by bitbox.follo.net (8.8.8/8.8.6) id FAA52229 for freebsd-arch@freebsd.org; Mon, 13 Dec 1999 05:27:37 +0100 (MET) Received: from picnic.mat.net (picnic.mat.net [206.246.122.133]) by hub.freebsd.org (Postfix) with ESMTP id 7DDEA14E87 for ; Sun, 12 Dec 1999 20:27:28 -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 XAA13769; Sun, 12 Dec 1999 23:25:49 -0500 (EST) (envelope-from chuckr@picnic.mat.net) Date: Sun, 12 Dec 1999 23:25:48 -0500 (EST) From: Chuck Robey To: "Russell L. Carter" Cc: Nate Williams , Arun Sharma , freebsd-arch@freebsd.org Subject: Re: Thread scheduling In-Reply-To: <19991211192742.4C7504A@pinyon.org> 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 Sat, 11 Dec 1999, Russell L. Carter wrote: > > %> Not a guarantee, but would it be a good thing to have them > %> "co-scheduled" (or a bias towards that likelihood). > % > %But, I can't see any advantage to have them co-scheduled. > > In the realm of parallel numerical algorithms there are > quite a lot of practical algorithms that require cross > "task" communication and to the extent that the "tasks" > are not executed in roughly synchronous fashion so that > their intricate communication schedules may be carried > out more or less non-blocking then the algorithm > suffers from disastrous multicpu inefficiency. > Typically, these "tasks" share miniscule amounts of data, > but any "waiting" is fatal to scalable throughput. > Hence the development of the "gang scheduling" notion > that Arun referred to. This is most highly refined > and effectively implemented in Cray UNICOS systems. > > But I wouldn't worry about it. It's a small slice of > the whole customer pie, and causes indigestion for > my particular fetish, which is independently > schedulable (ala POSIX) threads capable of > meeting QOS guarantees. :-) OK, thanks, guys. That question's done. I have more, but I need to investigate code now, so as not to waste more time. ---------------------------------------------------------------------------- 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