Date: Sat, 11 Dec 1999 12:27:42 -0700 From: "Russell L. Carter" <rcarter@pinyon.org> To: nate@mt.sri.com (Nate Williams) Cc: Chuck Robey <chuckr@picnic.mat.net>, Arun Sharma <adsharma@sharmas.dhs.org>, freebsd-arch@freebsd.org, rcarter@pinyon.org Subject: Re: Thread scheduling Message-ID: <19991211192742.4C7504A@pinyon.org> In-Reply-To: Message from Nate Williams <nate@mt.sri.com> of "Fri, 10 Dec 1999 21:55:29 MST." <199912110455.VAA24095@mt.sri.com>
next in thread | previous in thread | raw e-mail | index | archive | help
%> 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. :-) Russell % % % %Nate % To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?19991211192742.4C7504A>