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(measure_init): Improve it so that we don't measure noise, such

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as context-switches.

(Logical change 1.191)
This commit is contained in:
mostang.com!davidm 2004-03-28 00:24:33 +00:00
parent d73775b6cb
commit fc7b49b983
1 changed files with 59 additions and 31 deletions
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90
tests/Gperf-simple.c
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@ -39,7 +39,7 @@ static int maxlevel = 100;
#define MB (1024*1024)
static char big[128*MB];
static char big[512*MB];
static inline double
gettime (void)
@ -118,13 +118,14 @@ doit (const char *label)
}
static long
sum (char *buf, size_t size)
sum (void *buf, size_t size)
{
long s = 0;
char *cp = buf;
size_t i;
for (i = 0; i < size; ++i)
s += *buf++;
for (i = 0; i < size; i += 64)
s += *cp++;
return s;
}
@ -132,42 +133,69 @@ static void
measure_init (void)
{
# define N 1000
double stop, start, getcontext_cold, getcontext_warm, init_cold, init_warm;
# define M 10
double stop, start, get_cold, get_warm, init_cold, init_warm, delta;
unw_cursor_t cursor[N];
unw_context_t uc[N];
int i;
int i, j;
/* Ensure memory is paged in but not in the cache: */
memset (cursor, 0, sizeof (cursor));
memset (uc, 0, sizeof (uc));
dummy = sum (big, sizeof (big));
/* Run each test M times and take the minimum to filter out noise
such dynamic linker resolving overhead, context-switches,
page-in, cache, and TLB effects. */
start = gettime ();
for (i = 0; i < N; ++i)
unw_getcontext (&uc[i]);
stop = gettime ();
getcontext_cold = (stop - start) / N;
get_cold = 1e99;
for (j = 0; j < M; ++j)
{
dummy += sum (big, sizeof (big)); /* flush the cache */
start = gettime ();
for (i = 0; i < N; ++i)
unw_init_local (&cursor[i], &uc[i]);
stop = gettime ();
init_cold = (stop - start) / N;
start = gettime ();
for (i = 0; i < N; ++i)
unw_getcontext (&uc[i]);
stop = gettime ();
delta = (stop - start) / N;
if (delta < get_cold)
get_cold = delta;
}
//exit (0);
init_cold = 1e99;
for (j = 0; j < M; ++j)
{
dummy += sum (big, sizeof (big)); /* flush cache */
start = gettime ();
for (i = 0; i < N; ++i)
unw_init_local (&cursor[i], &uc[i]);
stop = gettime ();
delta = (stop - start) / N;
if (delta < init_cold)
init_cold = delta;
}
start = gettime ();
for (i = 0; i < N; ++i)
unw_getcontext (&uc[0]);
stop = gettime ();
getcontext_warm = (stop - start) / N;
get_warm = 1e99;
for (j = 0; j < M; ++j)
{
start = gettime ();
for (i = 0; i < N; ++i)
unw_getcontext (&uc[0]);
stop = gettime ();
delta = (stop - start) / N;
if (delta < get_warm)
get_warm = delta;
}
start = gettime ();
for (i = 0; i < N; ++i)
unw_init_local (&cursor[0], &uc[0]);
stop = gettime ();
init_warm = (stop - start) / N;
init_warm = 1e99;
for (j = 0; j < M; ++j)
{
start = gettime ();
for (i = 0; i < N; ++i)
unw_init_local (&cursor[0], &uc[0]);
stop = gettime ();
delta = (stop - start) / N;
if (delta < init_warm)
init_warm = delta;
}
printf ("unw_getcontext : cold avg=%9.3f nsec, warm avg=%9.3f nsec\n",
1e9 * getcontext_cold, 1e9 * getcontext_warm);
1e9 * get_cold, 1e9 * get_warm);
printf ("unw_init_local : cold avg=%9.3f nsec, warm avg=%9.3f nsec\n",
1e9 * init_cold, 1e9 * init_warm);
}