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Full Discussion: RDTSC use in C:
Top Forums Programming RDTSC use in C: Post 302324893 by otheus on Friday 12th of June 2009 06:47:03 AM
Old 06-12-2009
Sivaraman,

I need to re-phrase your question --- please tell me if this is correct: How does one find out (on Linux) whether the CPU is actually running at the speed specified in cpuinfo?

Instead of the sleep statement above, set an alarm for 10 seconds, do some CPU-intensive work, get the number of ticks, compare the clocks to find how long the CPU actually slept (setting an alarm does not guarantee anything) and calculate. Use gettimeofday() to get the actual time.
 
SLEEP(3)						   BSD Library Functions Manual 						  SLEEP(3)

NAME
sleep -- suspend thread execution for an interval measured in seconds LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <unistd.h> unsigned int sleep(unsigned int seconds); DESCRIPTION
The sleep() function suspends execution of the calling thread until either seconds seconds have elapsed or a signal is delivered to the thread and its action is to invoke a signal-catching function or to terminate the thread or process. System activity may lengthen the sleep by an indeterminate amount. This function is implemented using nanosleep(2) by pausing for seconds seconds or until a signal occurs. Consequently, in this implementa- tion, sleeping has no effect on the state of process timers, and there is no special handling for SIGALRM. RETURN VALUES
If the sleep() function returns because the requested time has elapsed, the value returned will be zero. If the sleep() function returns due to the delivery of a signal, the value returned will be the unslept amount (the requested time minus the time actually slept) in seconds. SEE ALSO
nanosleep(2), usleep(3) STANDARDS
The sleep() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1''). HISTORY
A sleep() function appeared in Version 7 AT&T UNIX. BSD
February 13, 1998 BSD
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