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// @(#) $Revision: 4.12 $ $Source: /judy/judy/src/apps/benchmark/timeit.c,v $
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// YOU MUST COMPILE THIS WITH ONE OF THESE DEFINED:
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// If NONE of these are defined, this whole code section is ifdef'd out to
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// avoid compile/link errors due to usage here of objects not defined in
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// timeit.h. See end of file.
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// TBD: Improve on this; possibly it's OK now not to ifdef this out, and get
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// default, low-res timing behavior; see timeit.h.
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// Compile with -D_TIMEIT_TEST to include a main program for testing; see
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#if (JU_HPUX_PA || JU_LINUX_IA32 || JU_LINUX_IPF)
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#define _TIMEIT_HIGHRES
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#ifdef _TIMEIT_HIGHRES
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#include <sys/time.h> // Win32 uses a whole different paradigm.
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#include <unistd.h> // for getopt(), which Win32 lacks.
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double USecPerClock; // usec per control register count.
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// ****************************************************************************
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// F I N D C P U S P E E D
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// Return microseconds per control/timer register count. Examples:
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// 0.002 for 500 MHz processor
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// 0.001 for 1 GHz processor
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double find_CPU_speed(void)
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double DeltaUSec; // Timing result in uSec.
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TIMER_vars(tm); // creates __TVBeg_tm, ...
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// (used for consistency with __START_HRTm)
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gettimeofday(&__TVBeg_tm, NULL); // get low-res time.
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__START_HRTm(tm); // get __start_tm (high-res).
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sleep(1); // time passes; 1 sec suffices.
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__END_HRTm(tm); // get __stop_tm (high-res).
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gettimeofday(&__TVEnd_tm, NULL); // get low-res time.
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// gettimeofday() returns usec; compute elapsed time:
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DeltaUSec = (((double) __TVEnd_tm.tv_sec * ((double) 1E6))
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+ (double) __TVEnd_tm.tv_usec)
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- (((double) __TVBeg_tm.tv_sec * ((double) 1E6))
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+ (double) __TVBeg_tm.tv_usec);
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// Control register returns ticks, and the ratio can now be computed:
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return (DeltaUSec / ((double) (__stop_tm - __start_tm)));
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#else // _TIMEIT_HIGHRES
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void dummy() {} // avoid "empty source file" warnings when no _TIMEIT_TEST.
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// ****************************************************************************
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// Ifdef the test main() separately, including #includes, for platforms that do
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// not define find_CPU_speed() above.
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#include <sys/time.h> // Win32 uses a whole different paradigm.
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#include <unistd.h> // for getopt(), which Win32 lacks.
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//#include <values.h> // for MAXDOUBLE
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#define MAXDOUBLE (10e99)
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// ****************************************************************************
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// Example code for timeit:
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// To compile and test this program on HP-UX, run the next lines as commands.
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// cc -Wl,-a,archive -DJU_HPUX_PA -D__HPUX__ -D_TIMEIT_TEST -o timeit timeit.c
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// timeit # run test program.
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// rm -f timeit # clean up after test.
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int main(int argc, char **argv)
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int i = 0; // loop index.
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long i_max = 10; // number of loops.
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int preload = 1; // loops to throw away (preload cache).
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double ztime; // timer overhead.
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double usec[4]; // for early timing tests.
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double DeltaUSec; // timing result in usec.
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double prevtime; // from previous loop.
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double mintime; // minimum event time.
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struct timeval tmjunk; // for throw-away syscall.
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TIMER_vars(tm1); // overall timer variables.
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TIMER_vars(tm2); // misc + loop timer variables.
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STARTTm(tm1); // whole program timer.
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// The first arg is the number of iterations (default is i_max):
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i = atoi(argv[1]) + preload;
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if (i > 0) i_max = (long)i;
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// Calculate timer overhead (ztime):
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#ifdef _TIMEIT_HIGHRES
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(void) puts("Possible slight delay here due to find_CPU_speed()...");
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(void) puts("No high-res clock or find_CPU_speed() for this platform.");
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for (i = 0; i < 100; ++i) // average many runs.
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ENDTm(DeltaUSec, tm2);
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ztime = ztime / ((double) i);
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// SIMPLE TESTS OF TIMER OVERHEAD:
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// Make two passes at both the high-res (if any) and slower timers.
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(void) puts("\nTiming timers themselves: start, end, end");
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#define PRINTPASS(Desc,Pass) \
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(void) printf("%-8s pass %d: %f - %f = %f usec\n", Desc, Pass, \
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usec[((Pass) * 2) - 1], usec[((Pass) * 2) - 2], \
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usec[((Pass) * 2) - 1] - usec[((Pass) * 2) - 2])
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#ifdef _TIMEIT_HIGHRES
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END_HRTm(usec[0], tm2); // throw away in case of sleep(1) here.
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END_HRTm(usec[0], tm2);
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END_HRTm(usec[1], tm2);
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END_HRTm(usec[2], tm2);
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END_HRTm(usec[3], tm2);
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PRINTPASS("High-res", 1);
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PRINTPASS("High-res", 2);
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ENDTm(usec[0], tm2); // throw away in case of sleep(1) here.
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PRINTPASS("Non-HR", 1);
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PRINTPASS("Non-HR", 2);
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// PRINT INITIAL INFO:
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#ifdef _TIMEIT_HIGHRES
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// Print the CPU speed:
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// Note: USecPerClock is a global set by the first instance of STARTTm. You
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// can also get this number by calling find_CPU_speed().
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(void) printf("\nClock step = %.3f nsec => %.1f MHz.\n",
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USecPerClock * 1000.0, 1.0 / USecPerClock);
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// Print timer overhead even though it's been subtracted from the reported
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(void) printf("Timer overhead subtracted from the times below = %f "
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// DO A FAST TIMER CHECK:
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(void) puts("\nCheck timer precision by repeating the same action:");
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(void) puts("Times in each group should be close together.");
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(void) puts("\nTiming something very fast: \"++i\":");
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for (i = 1; i <= i_max; ++i)
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prevtime = DeltaUSec;
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STARTTm(tm2); // start the timer.
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++i; // statement to time.
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ENDTm(DeltaUSec, tm2); // stop the timer.
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DeltaUSec -= ztime; // remove timer overhead.
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// Throw away the first loop iteration to warm up the cache:
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if (mintime == MAXDOUBLE) mintime = DeltaUSec;
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(void) printf("%3d. %8.3f nanosec,\tmintime diff %8.1f %%\n",
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i - preload, DeltaUSec * 1000.0,
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((DeltaUSec - mintime) * 100) / mintime);
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if (DeltaUSec < mintime) mintime = DeltaUSec;
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// TIME A FUNCTION CALL:
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(void) puts("\nTiming a function: \"gettimeofday()\":");
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for (i = 1; i <= i_max; ++i)
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prevtime = DeltaUSec;
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STARTTm(tm2); // start the timer.
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gettimeofday(&tmjunk, NULL); // burn some cycles.
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ENDTm(DeltaUSec, tm2); // stop the timer.
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DeltaUSec -= ztime; // remove timer overhead.
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// Throw away the first loop iteration to warm up the cache:
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if (mintime == MAXDOUBLE) mintime = DeltaUSec;
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(void) printf("%3d. %8.3f usec,\tmintime diff %8.1f %%\n",
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i - preload, DeltaUSec,
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((DeltaUSec - mintime) * 100) / mintime);
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if (DeltaUSec < mintime) mintime = DeltaUSec;
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// TIME SOMETHING SLOW:
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(void) puts("\nTiming something slow: \"sleep(1)\":");
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for (i = 1; i <= i_max; ++i)
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prevtime = DeltaUSec;
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STARTTm(tm2); // start the timer.
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ENDTm(DeltaUSec, tm2); // stop the timer.
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DeltaUSec -= ztime; // remove timer overhead.
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// Throw away the first loop iteration to warm up the cache:
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if (mintime == MAXDOUBLE) mintime = DeltaUSec;
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(void) printf("%3d. %8.3f sec,\tmintime diff %8.1f %%\n",
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i - preload, DeltaUSec/1E6,
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((DeltaUSec - mintime) * 100) / mintime);
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if (DeltaUSec < mintime) mintime = DeltaUSec;
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// Print program execution time:
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ENDTm(DeltaUSec, tm1);
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(void) printf("\nProgram execution time: %.3f sec\n", DeltaUSec / 1E6);
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#endif // #ifdef _TIMEIT_TEST
added
removed
test/timeit.c
