Re: [fpc-devel] High performance Linux timer
Felipe Monteiro de Carvalho wrote: I once implemented a high precision timer on linux, but I don't remember how I did it. Look at the code here: http://wiki.lazarus.freepascal.org/EpikTimer Thanks, I'll have a look at the code for more details. From the wiki, it sounds like there might be some issues EpikTimer implementation though. * Timestamp Counter. * Pentium IV 3,2Mhz on Windows and Linux with great precision (~ 3,220,000,000 ticks per second) Timestamp counter from the CPU (assuming we are speaking of RDTSC) is susceptible to many issue. eg: A Intel P4 3.2Mhz does not always produce 3,220,000,000 ticks per second. Powersaving features like SpeedStep, Hibernate etc all affect the CPU clock speed. Also on a multi-core system, not all cores are guaranteed to run at the same clock speed. Above information was gathered from the WikiPedia article. http://en.wikipedia.org/wiki/Rdtsc Anybody know what Win32's QueryPerformanceCounter() uses internally to get a stable timer? Or is QueryPerformanceCounter also susceptible to powersaving features? Regards, - Graeme - ___ fpGUI - a cross-platform GUI toolkit using Free Pascal http://opensoft.homeip.net/fpgui/ ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] High performance Linux timer
Hi, Graeme Geldenhuys wrote: Does anybody know if there is a Linux (or generic Unix) high performance timer API available. Something like the Win32 API QueryPerformanceCounter()? Graeme, maybe this link will help: http://www.gamedev.net/community/forums/topic.asp?topic_id=127700 There are some functions mentioned there in addition to RDTSC: - gettimeofday - clock_gettime - ftime Anybody know what Win32's QueryPerformanceCounter() uses internally to get a stable timer? Or is QueryPerformanceCounter also susceptible to powersaving features? I found an article named Beware of QueryPerformanceCounter() on http://www.virtualdub.org/blog/pivot/entry.php?id=106 that gives some information about this function. It will not answer your questions directly, but may be useful. -- Regards, Vladimir ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] High performance Linux timer
On Mon, May 19, 2008 at 4:31 AM, Graeme Geldenhuys [EMAIL PROTECTED] wrote: Timestamp counter from the CPU (assuming we are speaking of RDTSC) is susceptible to many issue... Read the line just bellow the one you just quoted: * Nanosecond resolution is supported on Intel Pentium versions with a Timestamp Counter. * Microsecond system clock is the default timebase. The default timebase doesn't use the hardware directly. -- Felipe Monteiro de Carvalho ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
[fpc-devel] High performance Linux timer
Hi, Does anybody know if there is a Linux (or generic Unix) high performance timer API available. Something like the Win32 API QueryPerformanceCounter()? Regards, - Graeme - ___ fpGUI - a cross-platform Free Pascal GUI toolkit http://opensoft.homeip.net/fpgui/ ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] High performance Linux timer
Hi! Does anybody know if there is a Linux (or generic Unix) high performance timer API available. Something like the Win32 API QueryPerformanceCounter()? Probably the Time-Stamp-Counter for your CPU is of interest for you. See http://en.wikipedia.org/wiki/Rdtsc for example code. Bye Hansi ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] High performance Linux timer
I once implemented a high precision timer on linux, but I don't remember how I did it. Look at the code here: http://wiki.lazarus.freepascal.org/EpikTimer -- Felipe Monteiro de Carvalho ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
