Newsgroups: comp.parallel From: Erik Demaine Subject: Re: timers for multiprocessors Organization: University of Waterloo Date: 3 Apr 1997 14:53:35 GMT Message-ID: <5i0g9f$kcd@server1.ctc.com> A Leservot wrote: : I am looking for a portable API multiprocessor timer for f90, which : would give me between two points (in a f90 program with some directives) : : [...] : 2) total cpu time used : 3) maximum number of cpu used : 4) cpu time used when the program is running on 1, 2, 3,...n processors. : Points 2) 3) and 4) are supplied with MTIMESX() Cray T90 function, but : I've not found similar function for DEC, SGI or IBM. First off: CPU time will not be very useful in most parallel applications, because it includes *some* of the communication time *but not all*, and the amount that it includes often varies. The omition of a CPU time routine in Fortran 90 is IMO a mistake. Meanwhile, you can use the following to determine the total number of seconds used so far on the local processor (then use MPI_Reduce to find max or sum, for example). You should probably take a difference between the current amount of time used and the time you thought you started at. * On RS/6000 (e.g., SP2): integer mclock seconds = mclock () / 100.0 * On most Berkeley UNIX: real etime, vec(2) seconds = etime (vec) * On Cray: real second seconds = second () Erik -- Erik Demaine () e-mail: eddemain@daisy.uwaterloo.ca Dept. of Computer Science || URL: http://daisy.uwaterloo.ca/~eddemain/ University of Waterloo || PGP key: finger me. "Maturity is switching Waterloo, ON Canada N2L 3G1 () from passive voice to active voice" -P. Alder -- Articles to parallel@ctc.com (Administrative: bigrigg@ctc.com) Archive: http://www.hensa.ac.uk/parallel/internet/usenet/comp.parallel