[PATCH 03/18] perf bench: Fix memcpy/memset output

From: Arnaldo Carvalho de Melo
Date: Thu Dec 11 2014 - 16:26:43 EST


From: Rabin Vincent <rabin.vincent@xxxxxxxx>

The memcpy and memset benchmarks return bogus results when iterations >
0 because the iterations value is not taken into account when
calculating the final result:

$ perf bench mem memset --only-prefault --length 1GB --iterations 1
# Running 'mem/memset' benchmark:
# Copying 1GB Bytes ...

20.798669 GB/Sec (with prefault)
$ perf bench mem memset --only-prefault --length 1GB --iterations 10
# Running 'mem/memset' benchmark:
# Copying 1GB Bytes ...

2.086576 GB/Sec (with prefault)
$ perf bench mem memset --only-prefault --length 1GB --iterations 100
# Running 'mem/memset' benchmark:
# Copying 1GB Bytes ...

212.840917 MB/Sec (with prefault)

Fix this.

Signed-off-by: Rabin Vincent <rabin.vincent@xxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Rabin Vincent <rabin@xxxxxx>
Cc: Rabin Vincent <rabinv@xxxxxxxx>
Link: http://lkml.kernel.org/r/1417535441-3965-3-git-send-email-rabin.vincent@xxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/bench/mem-memcpy.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/tools/perf/bench/mem-memcpy.c b/tools/perf/bench/mem-memcpy.c
index e18be70c8a47..6c14afe8c1b1 100644
--- a/tools/perf/bench/mem-memcpy.c
+++ b/tools/perf/bench/mem-memcpy.c
@@ -141,6 +141,7 @@ static int bench_mem_common(int argc, const char **argv,
{
int i;
size_t len;
+ double totallen;
double result_bps[2];
u64 result_cycle[2];

@@ -156,6 +157,7 @@ static int bench_mem_common(int argc, const char **argv,
init_cycle();

len = (size_t)perf_atoll((char *)length_str);
+ totallen = (double)len * iterations;

result_cycle[0] = result_cycle[1] = 0ULL;
result_bps[0] = result_bps[1] = 0.0;
@@ -219,10 +221,10 @@ static int bench_mem_common(int argc, const char **argv,
if (use_cycle) {
printf(" %14lf Cycle/Byte\n",
(double)result_cycle[0]
- / (double)len);
+ / totallen);
printf(" %14lf Cycle/Byte (with prefault)\n",
(double)result_cycle[1]
- / (double)len);
+ / totallen);
} else {
print_bps(result_bps[0]);
printf("\n");
@@ -233,7 +235,7 @@ static int bench_mem_common(int argc, const char **argv,
if (use_cycle) {
printf(" %14lf Cycle/Byte",
(double)result_cycle[pf]
- / (double)len);
+ / totallen);
} else
print_bps(result_bps[pf]);

@@ -244,8 +246,8 @@ static int bench_mem_common(int argc, const char **argv,
if (!only_prefault && !no_prefault) {
if (use_cycle) {
printf("%lf %lf\n",
- (double)result_cycle[0] / (double)len,
- (double)result_cycle[1] / (double)len);
+ (double)result_cycle[0] / totallen,
+ (double)result_cycle[1] / totallen);
} else {
printf("%lf %lf\n",
result_bps[0], result_bps[1]);
@@ -253,7 +255,7 @@ static int bench_mem_common(int argc, const char **argv,
} else {
if (use_cycle) {
printf("%lf\n", (double)result_cycle[pf]
- / (double)len);
+ / totallen);
} else
printf("%lf\n", result_bps[pf]);
}
@@ -324,7 +326,7 @@ static double do_memcpy_gettimeofday(const struct routine *r, size_t len,

free(src);
free(dst);
- return (double)((double)len / timeval2double(&tv_diff));
+ return (double)(((double)len * iterations) / timeval2double(&tv_diff));
}

int bench_mem_memcpy(int argc, const char **argv,
@@ -389,7 +391,7 @@ static double do_memset_gettimeofday(const struct routine *r, size_t len,
timersub(&tv_end, &tv_start, &tv_diff);

free(dst);
- return (double)((double)len / timeval2double(&tv_diff));
+ return (double)(((double)len * iterations) / timeval2double(&tv_diff));
}

static const char * const bench_mem_memset_usage[] = {
--
1.9.3

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