X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f From: Hans-Bernhard Broeker Newsgroups: comp.os.msdos.djgpp Subject: Re: RDTSC ? Date: 3 Dec 2001 12:54:07 GMT Organization: Aachen University of Technology (RWTH) Lines: 17 Message-ID: <9ufslf$lfo$1@nets3.rz.RWTH-Aachen.DE> References: NNTP-Posting-Host: acp3bf.physik.rwth-aachen.de X-Trace: nets3.rz.RWTH-Aachen.DE 1007384047 22008 137.226.32.75 (3 Dec 2001 12:54:07 GMT) X-Complaints-To: abuse AT rwth-aachen DOT de NNTP-Posting-Date: 3 Dec 2001 12:54:07 GMT Originator: broeker@ To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Reply-To: djgpp AT delorie DOT com Damien Knight wrote: > As I've been told, RDTSC is a feature of pentium (and up) processers that > tracks the number of processer cycles completed since the system last > powered up, making it useful for calculating system uptime IIRC, uptime is probably the one thing RDTSC is least useful for. The counters overflow much too early for that. Note that these counters run with CPU clock speed, i.e. more than a billion ticks per second. The RDTSC stuff is really meant for code optimization tests. You can not just count ticks, but several types of CPU-internal events relevant for program performance, like cache misses or pipeline stalls. -- Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de) Even if all the snow were burnt, ashes would remain.