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A small correction to account for the non-loop instructions in busy_sse_loop()

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git-svn-id: https://svn.code.sf.net/p/libcpuid/code/HEAD/libcpuid@82 3b4be424-7ac5-41d7-8526-f4ddcb85d872
This commit is contained in:
Veselin Georgiev 2010-04-20 09:59:12 +00:00
parent 4802081283
commit b922a5b29c
1 changed files with 6 additions and 3 deletions
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9
libcpuid/rdtsc.c
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@ -243,14 +243,15 @@ int cpu_clock_by_ic(int millis, int runs)
int max_value = 0, cur_value, i, ri, cycles_inner, cycles_outer, c;
struct cpu_id_t* id;
uint64_t t0, t1, tl, hz;
int num_instructions = 256000000;
int num_instructions = 256;
int sse_multiplier = 1;
if (millis <= 0 || runs <= 0) return -2;
id = get_cached_cpuid();
if (!id || !id->flags[CPU_FEATURE_SSE]) return -1;
//
if (!sse_is_128_bit(id)) {
debugf(1, "SSE execution path is 64-bit\n");
num_instructions *= 2;
sse_multiplier = 2;
} else {
debugf(1, "SSE execution path is 128-bit\n");
}
@ -278,7 +279,9 @@ int cpu_clock_by_ic(int millis, int runs)
} while (t1 - t0 < tl * (uint64_t) 8);
// cpu_Hz = cycles_inner * cycles_outer * 256 / (t1 - t0) * 1000000
debugf(2, "c = %d, td = %llu\n", c, t1 - t0);
hz = (uint64_t) cycles_inner * (uint64_t) cycles_outer * (uint64_t) c * (uint64_t) num_instructions / (t1 - t0);
hz = ((uint64_t) cycles_inner * (uint64_t) num_instructions + 8) *
(uint64_t) cycles_outer * (uint64_t) sse_multiplier * (uint64_t) c * (uint64_t) 1000000
/ (t1 - t0);
cur_value = (int) (hz / 1000000);
if (cur_value > max_value) max_value = cur_value;
}