FEX-Emu/xxHash
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update internal benchmark

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to reduce risks of rounding bias
when a measurement uses a too small amount of time.
This commit is contained in:
Yann Collet 2019-12-10 13:12:28 -08:00
parent c173142da0
commit ae245428b8
1 changed files with 24 additions and 14 deletions
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38
xxhsum.c
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@ -260,7 +260,8 @@ static const char author[] = "Yann Collet";
static size_t XXH_DEFAULT_SAMPLE_SIZE = 100 KB;
#define NBLOOPS 3 /* Default number of benchmark iterations */
#define TIMELOOP_S 1
#define TIMELOOP (TIMELOOP_S * CLOCKS_PER_SEC) /* Minimum timing per iteration */
#define TIMELOOP (TIMELOOP_S * CLOCKS_PER_SEC) /* target timing per iteration */
#define TIMELOOP_MIN (TIMELOOP / 2) /* minimum timing to validate a result */
#define XXHSUM32_DEFAULT_SEED 0 /* Default seed for algo_xxh32 */
#define XXHSUM64_DEFAULT_SEED 0 /* Default seed for algo_xxh64 */
@ -376,26 +377,36 @@ static void BMK_benchHash(hashFunction h, const char* hName, const void* buffer,
if (r==0) DISPLAYLEVEL(3,".\r"); /* do something with r to defeat compiler "optimizing" away hash */
{ clock_t const nbTicks = BMK_clockSpan(cStart);
double const timeS = ((double)nbTicks / CLOCKS_PER_SEC) / nbh_perIteration;
if (nbTicks == 0) { /* faster than resolution timer */
nbh_perIteration *= 100;
double const ticksPerHash = ((double)nbTicks / TIMELOOP) / nbh_perIteration;
if (nbTicks < TIMELOOP_MIN) {
/* not enough time spent in benchmarking, risk of rounding bias */
if (nbTicks == 0) { /* faster than resolution timer */
nbh_perIteration *= 100;
} else {
/* update nbh_perIteration so that next round last approximately 1 second */
double nbh_perSecond = (1 / ticksPerHash) + 1;
if (nbh_perSecond > (double)(4000U<<20)) nbh_perSecond = (double)(4000U<<20); /* avoid overflow */
nbh_perIteration = (U32)nbh_perSecond;
}
iterationNb--; /* try again */
continue;
}
if (timeS < fastestH) fastestH = timeS;
if (ticksPerHash < fastestH) fastestH = ticksPerHash;
DISPLAYLEVEL(2, "%1u-%-22.22s : %10u -> %8.0f it/s (%7.1f MB/s) \r",
iterationNb, hName, (U32)bufferSize,
(double)1 / fastestH,
((double)bufferSize / (1<<20)) / fastestH );
iterationNb, hName, (U32)bufferSize,
(double)1 / fastestH,
((double)bufferSize / (1 MB)) / fastestH );
}
{ double nbh_perSecond = (1 / fastestH) + 1;
if (nbh_perSecond > (double)(4000U<<20)) nbh_perSecond = (double)(4000U<<20);
if (nbh_perSecond > (double)(4000U<<20)) nbh_perSecond = (double)(4000U<<20); /* avoid overflow */
nbh_perIteration = (U32)nbh_perSecond;
}
}
DISPLAYLEVEL(1, "%-24.24s : %10u -> %8.0f it/s (%7.1f MB/s) \n", hName, (U32)bufferSize,
(double)1 / fastestH,
((double)bufferSize / (1<<20)) / fastestH);
DISPLAYLEVEL(1, "%-24.24s : %10u -> %8.0f it/s (%7.1f MB/s) \n",
hName, (U32)bufferSize,
(double)1 / fastestH,
((double)bufferSize / (1 MB)) / fastestH );
if (g_displayLevel<1)
DISPLAYLEVEL(0, "%u, ", (U32)((double)1 / fastestH));
}
@ -546,8 +557,7 @@ static int BMK_benchInternal(size_t keySize, U32 specificTest)
{ int const result = BMK_benchMem(alignedBuffer, keySize, specificTest);
free(buffer);
return result;
}
}
} }
}