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Prefer CPU performance counters (if available) over gettimeofday.

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I've seen this improve the std. deviation often by a factor of 2
and occasionally up to a factor of 10. It is sometimes not much
better, but never seems to be appreciably worse compared to using
gettimeofday.

Thanks to David A. Schleef <ds@schleef.org> and his liboil for
the implementation.
This commit is contained in:
Carl Worth 2006-09-06 01:37:13 -07:00
parent 1085d99bc3
commit d9082d59db
1 changed files with 116 additions and 8 deletions
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124
perf/cairo-perf-posix.c
View file

@ -25,6 +25,34 @@
* Carl Worth <cworth@cworth.org>
*/
/* Portions of this file come from liboil:
*
* LIBOIL - Library of Optimized Inner Loops
* Copyright (c) 2003,2004 David A. Schleef <ds@schleef.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <signal.h>
#include <sys/time.h>
#include <unistd.h>
@ -36,37 +64,117 @@
/* timers */
#if defined(__i386__) || defined(__amd64__)
static inline unsigned long
oil_profile_stamp_rdtsc (void)
{
unsigned long ts;
__asm__ __volatile__("rdtsc\n" : "=a" (ts) : : "edx");
return ts;
}
#define OIL_STAMP oil_profile_stamp_rdtsc
#endif
#if defined(__powerpc__) || defined(__PPC__) || defined(__ppc__)
static inline cairo_perf_ticks_t
oil_profile_stamp_tb(void)
{
unsigned long ts;
__asm__ __volatile__("mftb %0\n" : "=r" (ts));
return ts;
}
#define OIL_STAMP oil_profile_stamp_tb
#endif
#if defined(__alpha__)
static inline cairo_perf_ticks_t
oil_profile_stamp_alpha(void)
{
unsigned int ts;
__asm__ __volatile__ ("rpcc %0\n" : "=r"(ts));
return ts;
}
#define OIL_STAMP oil_profile_stamp_alpha
#endif
#if defined(__s390__)
static cairo_perf_ticks_t
oil_profile_stamp_s390(void)
{
uint64_t ts;
__asm__ __volatile__ ("STCK %0\n" : : "m" (ts));
return ts;
}
#define OIL_STAMP oil_profile_stamp_s390
#endif
typedef struct _cairo_perf_timer
{
struct timeval start;
struct timeval stop;
#ifdef OIL_STAMP
cairo_perf_ticks_t start;
cairo_perf_ticks_t stop;
#else
struct timeval tv_start;
struct timeval tv_stop;
#endif
} cairo_perf_timer_t;
static cairo_perf_timer_t timer;
void
cairo_perf_timer_start (void) {
gettimeofday (&timer.start, NULL);
#ifdef OIL_STAMP
timer.start = OIL_STAMP ();
#else
gettimeofday (&timer.tv_start, NULL);
#endif
}
void
cairo_perf_timer_stop (void) {
gettimeofday (&timer.stop, NULL);
#ifdef OIL_STAMP
timer.stop = OIL_STAMP ();
#else
gettimeofday (&timer.tv_stop, NULL);
#endif
}
cairo_perf_ticks_t
cairo_perf_timer_elapsed (void) {
cairo_perf_ticks_t usec;
cairo_perf_ticks_t ticks;
usec = (timer.stop.tv_sec - timer.start.tv_sec) * 1000000;
usec += (timer.stop.tv_usec - timer.start.tv_usec);
#ifdef OIL_STAMP
ticks = (timer.stop - timer.start);
#else
ticks = (timer.tv_stop.tv_sec - timer.tv_start.tv_sec) * 1000000;
ticks += (timer.tv_stop.tv_usec - timer.tv_start.tv_usec);
#endif
return usec;
return ticks;
}
cairo_perf_ticks_t
cairo_perf_ticks_per_second (void) {
#ifdef OIL_STAMP
static cairo_perf_ticks_t tps = 0;
/* XXX: This is obviously not stable in light of changing CPU speed. */
if (tps == 0) {
struct timeval tv_start, tv_stop;
double tv_elapsed;
cairo_perf_timer_start ();
gettimeofday (&tv_start, NULL);
sleep (1);
cairo_perf_timer_stop ();
gettimeofday (&tv_stop, NULL);
tv_elapsed = ((tv_stop.tv_sec - tv_start.tv_sec) +
+ (tv_stop.tv_usec - tv_start.tv_usec) / 1000000.0);
tps = round (cairo_perf_timer_elapsed () / tv_elapsed);
}
return tps;
#else
/* For gettimeofday the units are micro-seconds */
return 1000000;
#endif
}
/* yield */