site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com On Jan 30, 2009, at 3:22 PM, Jason Coco wrote: On Jan 30, 2009, at 16:01 , Andy Wiese wrote: On Jan 30, 2009, at 9:05 AM, Jason Coco wrote: On Jan 30, 2009, at 09:27 , Christopher Khaljah Xu wrote: Hi there! I'm a rookie on a mac. I've been trying to port some windows programs that was written in C/C++ onto the mac. I need to rewrite a timer that measures CPU ticks between the start and end of an operation. I wonder if there is something in the mac api similar as GetTickCount or GetTickCount64 ? You can use mach_absolute_time() (declared in mach/mach_time.h) for this purpose. For more information on using this routine, see this technical qa: http://developer.apple.com/qa/qa2004/qa1398.html Jason How does clock(3) compare to mach_absolute_time()? mach_absolute_time() actually counts the clock cycles and is the reference timer for everything else. Internally, from the C library, clock(3) calls getrusage(2) on itself and returns the converted sum of its system and user time. So resolution issues aside (I understand that clock is low resolution), clock(3) attempts to measure the cpu usage of the particular process, and mach_absolute_time will give the system global cpu time. Correct? So for my purposes, I want rough measurements of a single relatively long-running task (a cgi handler) in an environment that is polluted with many such processes, so clock(3) is actually a pretty good choice. (The fact that the deployment environment is FreeBSD makes it an even better choice, but that is off-topic and off-platform). _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... This email sent to site_archiver@lists.apple.com