Path: utzoo!attcan!uunet!cs.utexas.edu!halley!foghorn.mpd.tandem.com!tjd From: tjd@foghorn.mpd.tandem.com (Tom Davidson) Newsgroups: comp.arch Subject: Re: Cycle Counter Keywords: Performance Message-ID: <559@halley.UUCP> Date: 10 Aug 89 13:35:43 GMT References: Sender: news@halley.UUCP Distribution: comp Organization: One of those ex-ETA people.... Lines: 30 >Not that if makes much difference, but the ETA-10 has several extra registers >to keep track of cycle counts for the vector and scalar units. Actually, for performance analysis, the ETA10 had some rather useful hardware. AS John mentions, some "registers" kept such goodies as a clock counter (in whatever periods the particular cpu was running: 7, 10.5, 19ns etc), vector unit busy. It also had 5 programmable counters which could be set to track such things as . number of in stack branches . number of branches NOT taken . number of times opcode xx was executed and a whole host of other neat things. All this could be accesed from a fortran program. These counters were kept on a per-process basis in a state area called an "invisible package". Performance analysis and code profiling were made a lot easier with this type of hardware feature. I hope h/w architects are doing the same.... Tom Tom Davidson internet: halley!foghorn!tjd@cs.utexas.edu Tandem Computers, Inc. fax: (512) 244-8247 voice: (512) 244-8375 14231 Tandem Boulevard Austin, TX 78728-6610