Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!aero!aerospace.aero.org!carl From: carl@aerospace.aero.org (Carl Kesselman) Newsgroups: comp.sys.sequent Subject: Re: timing parallel programs Message-ID: <67411@aerospace.AERO.ORG> Date: 24 Feb 90 07:31:10 GMT References: <1324@csisles.Bristol.AC.UK> <1803@baird.cs.strath.ac.uk> <11171@encore.Encore.COM> Sender: news@aerospace.aero.org Reply-To: carl@altair.UUCP (Carl Kesselman) Organization: The Aerospace Corporation, El-Segundo, CA Lines: 18 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. If you have the appropiate kernel configuration, this can be done without root permission. You might also want to dissable swapping and pff reduction of the working set using the vm_ctl system call. This does not completly free you from interaction with other programs, but it is pretty good. In particular, you still must share the system bus and disk controllers with other processes. In addition, you should always leave a processor or two free to handle interupts, network traffic and the like. NOTE: there is about a 20 microsecond overhead if you use the function call interface described in the manual page. There is also a set of macros defined that can allow you to access the clock in about 6 usecs. Carl