Brian Ford wrote:
Put this in its own (separate from all Cygwin code) object file, call it before any timing calls in your application, and link it with -lwinmm:#include "windows.h" void SetSchedulerMaxRes(void) { TIMECAPS tc; /* Set the system scheduler resolution to its maximum. * Needed for Cygwin >= 1.5.20, broken in 1.5.19, and unnecessary * <= 1.5.18 because it was always done by Cygwin. Required for */ if (timeGetDevCaps(&tc, sizeof(tc)) != TIMERR_NOERROR) { printf("timeGetDevCaps error %d\n", GetLastError()); tc.wPeriodMin = 1; /* Try 1 ms and hope for the best */ } if (timeBeginPeriod(tc.wPeriodMin) != TIMERR_NOERROR) printf("timeBeginPeriod error %d\n", GetLastError()); }
Impressive. I never knew about timeGetDevCaps nor timeBeginPeriod but this improved the sleep time by making it accurate up to 1000 microseconds, which *is* the behavior I've been looking for for weeks now. Here's the new output on my box: $ ./a.exe Print elapsed time at every call to usleep() Elapsed time (sec:microsec) 0:100000 Elapsed time (sec:microsec) 0:101000 Elapsed time (sec:microsec) 0:100000 Elapsed time (sec:microsec) 0:101000 Elapsed time (sec:microsec) 0:101000 Elapsed time (sec:microsec) 0:100000 Elapsed time (sec:microsec) 0:101000 Elapsed time (sec:microsec) 0:100000 Elapsed time (sec:microsec) 0:101000 Elapsed time (sec:microsec) 0:100000 Print elapsed after the loop() Elapsed time (sec:microsec) 1:26000 Thank you very much. Best Regards, Carlo -- Carlo Florendo Softare Engineer/Network Co-Administrator Astra Philippines Inc. UP-Ayala Technopark, Diliman 1101, Quezon City Philippines http://www.astra.ph Member of the Astra Group of Companies 5-3-11 Sekido, Tama City Tokyo 206-0011, Japan http://www.astra.co.jp -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
