Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!strath-cs!jim From: jim@cs.strath.ac.uk (Jim Reid) Newsgroups: comp.sys.sequent Subject: Re: timing parallel programs Message-ID: <2151@baird.cs.strath.ac.uk> Date: 26 Feb 90 13:19:01 GMT References: <1324@csisles.Bristol.AC.UK> <1803@baird.cs.strath.ac.uk> <11171@encore.Encore.COM> <67411@aerospace.AERO.ORG> Sender: news@cs.strath.ac.uk Reply-To: jim@cs.strath.ac.uk Organization: Comp. Sci. Dept., Strathclyde Univ., Scotland. Lines: 19 In article <67411@aerospace.AERO.ORG> carl@altair.UUCP (Carl Kesselman) writes: >No, no no. The responses being sent are wrong. How about RTFM. There >is a facility called tmp_affinity. You can use this to ensure that a >process runs on a specific processor. Yes, but that is not much help to the person who posed the initial question. They were looking for a way to *exclusively* dedicate a processor (or bunch of processors) to a particular process. The tmp_affinity() system call does not provide this facility. It can bind a process to a particular processor, but does not prevent another process from also being bound to that processor or for the processor to be given over to interrupt servicing and related kernel processing. If the processor had to switch from the process that was being timed, the benchmark results would be inconsistent and possibly non-reproducible. I understand that Encore provide this capability on their boxes, so maybe DYNIX will get it some day. Jim