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Groups > linux.kernel > #1250437
| From | Ingo Molnar <mingo@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 05/14] perf/bench: Remove the prefaulting complication from 'perf bench mem mem*' |
| Date | 2015-10-19 10:20 +0200 |
| Message-ID | <qldPI-74y-15@gated-at.bofh.it> (permalink) |
| References | <qldG1-6ST-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
So 'perf bench mem memcpy/memset' has elaborate code to measure
memcpy()/memset() performance both with freshly allocated buffers
(which includes initial page fault overhead) and with preallocated
buffers.
But the thing is, the resulting bandwidth results are mostly
meaningless, because page faults dominate so much of the cost.
It might make sense to measure cache cold vs. cache hot performance,
but the code does not do this.
So remove this complication, and always prefault the ranges before
using them.
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
tools/perf/bench/mem-functions.c | 146 ++++++++++++++++++++---------------------------------------
1 file changed, 50 insertions(+), 96 deletions(-)
diff --git a/tools/perf/bench/mem-functions.c b/tools/perf/bench/mem-functions.c
index 8f91c2e6b459..33de5d57a163 100644
--- a/tools/perf/bench/mem-functions.c
+++ b/tools/perf/bench/mem-functions.c
@@ -28,8 +28,6 @@ static const char *routine = "all";
static int iterations = 1;
static bool use_cycle;
static int cycle_fd;
-static bool only_prefault;
-static bool no_prefault;
static const struct option options[] = {
OPT_STRING('l', "length", &length_str, "1MB",
@@ -41,10 +39,6 @@ static const struct option options[] = {
"repeat memcpy() invocation this number of times"),
OPT_BOOLEAN('c', "cycle", &use_cycle,
"Use cycles event instead of gettimeofday() for measuring"),
- OPT_BOOLEAN('o', "only-prefault", &only_prefault,
- "Show only the result with page faults before memcpy()"),
- OPT_BOOLEAN('n', "no-prefault", &no_prefault,
- "Show only the result without page faults before memcpy()"),
OPT_END()
};
@@ -110,103 +104,60 @@ static double timeval2double(struct timeval *ts)
return (double)ts->tv_sec + (double)ts->tv_usec / (double)1000000;
}
-#define print_bps(x) do { \
- if (x < K) \
- printf(" %14lf B/Sec", x); \
- else if (x < K * K) \
- printf(" %14lfd KB/Sec", x / K); \
- else if (x < K * K * K) \
- printf(" %14lf MB/Sec", x / K / K); \
- else \
- printf(" %14lf GB/Sec", x / K / K / K); \
+#define print_bps(x) do { \
+ if (x < K) \
+ printf(" %14lf B/Sec\n", x); \
+ else if (x < K * K) \
+ printf(" %14lfd KB/Sec\n", x / K); \
+ else if (x < K * K * K) \
+ printf(" %14lf MB/Sec\n", x / K / K); \
+ else \
+ printf(" %14lf GB/Sec\n", x / K / K / K); \
} while (0)
struct bench_mem_info {
const struct routine *routines;
- u64 (*do_cycle)(const struct routine *r, size_t len, bool prefault);
- double (*do_gettimeofday)(const struct routine *r, size_t len, bool prefault);
+ u64 (*do_cycle)(const struct routine *r, size_t len);
+ double (*do_gettimeofday)(const struct routine *r, size_t len);
const char *const *usage;
};
static void __bench_mem_routine(struct bench_mem_info *info, int r_idx, size_t len, double totallen)
{
const struct routine *r = &info->routines[r_idx];
- double result_bps[2];
- u64 result_cycle[2];
- int prefault = no_prefault ? 0 : 1;
-
- result_cycle[0] = result_cycle[1] = 0ULL;
- result_bps[0] = result_bps[1] = 0.0;
+ double result_bps = 0.0;
+ u64 result_cycle = 0;
printf("Routine %s (%s)\n", r->name, r->desc);
if (bench_format == BENCH_FORMAT_DEFAULT)
printf("# Copying %s Bytes ...\n\n", length_str);
- if (!only_prefault && prefault) {
- /* Show both results: */
- if (use_cycle) {
- result_cycle[0] = info->do_cycle(r, len, false);
- result_cycle[1] = info->do_cycle(r, len, true);
- } else {
- result_bps[0] = info->do_gettimeofday(r, len, false);
- result_bps[1] = info->do_gettimeofday(r, len, true);
- }
+ if (use_cycle) {
+ result_cycle = info->do_cycle(r, len);
} else {
- if (use_cycle)
- result_cycle[prefault] = info->do_cycle(r, len, only_prefault);
- else
- result_bps[prefault] = info->do_gettimeofday(r, len, only_prefault);
+ result_bps = info->do_gettimeofday(r, len);
}
switch (bench_format) {
case BENCH_FORMAT_DEFAULT:
- if (!only_prefault && prefault) {
- if (use_cycle) {
- printf(" %14lf Cycle/Byte\n",
- (double)result_cycle[0]
- / totallen);
- printf(" %14lf Cycle/Byte (with prefault)\n",
- (double)result_cycle[1]
- / totallen);
- } else {
- print_bps(result_bps[0]);
- printf("\n");
- print_bps(result_bps[1]);
- printf(" (with prefault)\n");
- }
+ if (use_cycle) {
+ printf(" %14lf Cycle/Byte\n", (double)result_cycle/totallen);
} else {
- if (use_cycle) {
- printf(" %14lf Cycle/Byte",
- (double)result_cycle[prefault]
- / totallen);
- } else
- print_bps(result_bps[prefault]);
-
- printf("%s\n", only_prefault ? " (with prefault)" : "");
+ print_bps(result_bps);
}
break;
+
case BENCH_FORMAT_SIMPLE:
- if (!only_prefault && prefault) {
- if (use_cycle) {
- printf("%lf %lf\n",
- (double)result_cycle[0] / totallen,
- (double)result_cycle[1] / totallen);
- } else {
- printf("%lf %lf\n",
- result_bps[0], result_bps[1]);
- }
+ if (use_cycle) {
+ printf("%lf\n", (double)result_cycle/totallen);
} else {
- if (use_cycle) {
- printf("%lf\n", (double)result_cycle[prefault]
- / totallen);
- } else
- printf("%lf\n", result_bps[prefault]);
+ printf("%lf\n", result_bps);
}
break;
+
default:
- /* Reaching this means there's some disaster: */
- die("unknown format: %d\n", bench_format);
+ BUG_ON(1);
break;
}
}
@@ -219,11 +170,6 @@ static int bench_mem_common(int argc, const char **argv, struct bench_mem_info *
argc = parse_options(argc, argv, options, info->usage, 0);
- if (no_prefault && only_prefault) {
- fprintf(stderr, "Invalid options: -o and -n are mutually exclusive\n");
- return 1;
- }
-
if (use_cycle)
init_cycle();
@@ -235,10 +181,6 @@ static int bench_mem_common(int argc, const char **argv, struct bench_mem_info *
return 1;
}
- /* Same as without specifying either of prefault and no-prefault: */
- if (only_prefault && no_prefault)
- only_prefault = no_prefault = false;
-
if (!strncmp(routine, "all", 3)) {
for (i = 0; info->routines[i].name; i++)
__bench_mem_routine(info, i, len, totallen);
@@ -278,7 +220,7 @@ static void memcpy_alloc_mem(void **dst, void **src, size_t length)
memset(*src, 0, length);
}
-static u64 do_memcpy_cycle(const struct routine *r, size_t len, bool prefault)
+static u64 do_memcpy_cycle(const struct routine *r, size_t len)
{
u64 cycle_start = 0ULL, cycle_end = 0ULL;
void *src = NULL, *dst = NULL;
@@ -287,8 +229,11 @@ static u64 do_memcpy_cycle(const struct routine *r, size_t len, bool prefault)
memcpy_alloc_mem(&dst, &src, len);
- if (prefault)
- fn(dst, src, len);
+ /*
+ * We prefault the freshly allocated memory range here,
+ * to not measure page fault overhead:
+ */
+ fn(dst, src, len);
cycle_start = get_cycle();
for (i = 0; i < iterations; ++i)
@@ -300,7 +245,7 @@ static u64 do_memcpy_cycle(const struct routine *r, size_t len, bool prefault)
return cycle_end - cycle_start;
}
-static double do_memcpy_gettimeofday(const struct routine *r, size_t len, bool prefault)
+static double do_memcpy_gettimeofday(const struct routine *r, size_t len)
{
struct timeval tv_start, tv_end, tv_diff;
memcpy_t fn = r->fn.memcpy;
@@ -309,8 +254,11 @@ static double do_memcpy_gettimeofday(const struct routine *r, size_t len, bool p
memcpy_alloc_mem(&dst, &src, len);
- if (prefault)
- fn(dst, src, len);
+ /*
+ * We prefault the freshly allocated memory range here,
+ * to not measure page fault overhead:
+ */
+ fn(dst, src, len);
BUG_ON(gettimeofday(&tv_start, NULL));
for (i = 0; i < iterations; ++i)
@@ -321,6 +269,7 @@ static double do_memcpy_gettimeofday(const struct routine *r, size_t len, bool p
free(src);
free(dst);
+
return (double)(((double)len * iterations) / timeval2double(&tv_diff));
}
@@ -343,7 +292,7 @@ static void memset_alloc_mem(void **dst, size_t length)
die("memory allocation failed - maybe length is too large?\n");
}
-static u64 do_memset_cycle(const struct routine *r, size_t len, bool prefault)
+static u64 do_memset_cycle(const struct routine *r, size_t len)
{
u64 cycle_start = 0ULL, cycle_end = 0ULL;
memset_t fn = r->fn.memset;
@@ -352,8 +301,11 @@ static u64 do_memset_cycle(const struct routine *r, size_t len, bool prefault)
memset_alloc_mem(&dst, len);
- if (prefault)
- fn(dst, -1, len);
+ /*
+ * We prefault the freshly allocated memory range here,
+ * to not measure page fault overhead:
+ */
+ fn(dst, -1, len);
cycle_start = get_cycle();
for (i = 0; i < iterations; ++i)
@@ -364,8 +316,7 @@ static u64 do_memset_cycle(const struct routine *r, size_t len, bool prefault)
return cycle_end - cycle_start;
}
-static double do_memset_gettimeofday(const struct routine *r, size_t len,
- bool prefault)
+static double do_memset_gettimeofday(const struct routine *r, size_t len)
{
struct timeval tv_start, tv_end, tv_diff;
memset_t fn = r->fn.memset;
@@ -374,8 +325,11 @@ static double do_memset_gettimeofday(const struct routine *r, size_t len,
memset_alloc_mem(&dst, len);
- if (prefault)
- fn(dst, -1, len);
+ /*
+ * We prefault the freshly allocated memory range here,
+ * to not measure page fault overhead:
+ */
+ fn(dst, -1, len);
BUG_ON(gettimeofday(&tv_start, NULL));
for (i = 0; i < iterations; ++i)
--
2.1.4
--
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Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 00/14] perf bench: Misc improvements Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:10 +0200
[PATCH 12/14] perf/bench: Harmonize all the -l/--nr_loops options Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:10 +0200
[tip:perf/core] perf bench: Harmonize all the -l/ --nr_loops options tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 09/14] perf/bench/mem: Fix 'length' vs. 'size' naming confusion Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:10 +0200
[tip:perf/core] perf bench mem: Fix 'length' vs. 'size' naming confusion tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 07/14] perf/bench/mem: Change 'cycle' to 'cycles' Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:10 +0200
[tip:perf/core] perf bench mem: Change 'cycle' to 'cycles' tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 14/14] perf/bench: Run benchmarks, don't test them Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:10 +0200
[tip:perf/core] perf bench: Run benchmarks, don't test them tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 10/14] perf/bench/mem: Improve user visible strings Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:10 +0200
[tip:perf/core] perf bench mem: Improve user visible strings tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 11/14] perf/bench/mem: Reorganize the code a bit Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:10 +0200
[tip:perf/core] perf bench mem: Reorganize the code a bit tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 13/14] perf/bench/mem: Rename 'routine' to 'function' Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:10 +0200
[tip:perf/core] perf bench mem: Rename 'routine' to 'function' tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 08/14] perf/bench/mem: Rename 'routine' to 'routine_str' Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:10 +0200
Re: [PATCH 08/14] perf/bench/mem: Rename 'routine' to 'routine_str' David Ahern <dsahern@gmail.com> - 2015-10-19 15:40 +0200
Re: [PATCH 08/14] perf/bench/mem: Rename 'routine' to 'routine_str' Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-10-19 21:00 +0200
Re: [PATCH 08/14] perf/bench/mem: Rename 'routine' to 'routine_str' Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-10-19 21:00 +0200
Re: [PATCH 08/14] perf/bench/mem: Rename 'routine' to 'routine_str' Ingo Molnar <mingo@kernel.org> - 2015-10-19 21:10 +0200
Re: [PATCH 08/14] perf/bench/mem: Rename 'routine' to 'routine_str' Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-10-19 21:30 +0200
Re: [PATCH 08/14] perf/bench/mem: Rename 'routine' to 'routine_str' Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-10-19 21:30 +0200
Re: [PATCH 08/14] perf/bench/mem: Rename 'routine' to 'routine_str' Ingo Molnar <mingo@kernel.org> - 2015-10-20 09:40 +0200
[tip:perf/core] perf bench mem: Rename 'routine' to 'routine_str' tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 02/14] perf/bench: Default to all routines in 'perf bench mem' Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:20 +0200
Re: [PATCH 02/14] perf/bench: Default to all routines in 'perf bench mem' Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-19 17:30 +0200
Re: [PATCH 02/14] perf/bench: Default to all routines in 'perf bench mem' Ingo Molnar <mingo@kernel.org> - 2015-10-19 19:50 +0200
[tip:perf/core] perf bench: Default to all routines in ' perf bench mem' tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 06/14] perf/bench: List output formatting options on 'perf bench -h' Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:20 +0200
Re: [PATCH 06/14] perf/bench: List output formatting options on 'perf bench -h' David Ahern <dsahern@gmail.com> - 2015-10-19 15:30 +0200
Re: [PATCH 06/14] perf/bench: List output formatting options on 'perf bench -h' Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-10-19 21:00 +0200
[tip:perf/core] perf bench: List output formatting options on ' perf bench -h' tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 05/14] perf/bench: Remove the prefaulting complication from 'perf bench mem mem*' Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:20 +0200
[tip:perf/core] perf bench: Remove the prefaulting complication from 'perf bench mem mem*' tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 04/14] perf/bench: Rename 'mem-memcpy.c' => 'mem-functions.c' Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:20 +0200
Re: [PATCH 04/14] perf/bench: Rename 'mem-memcpy.c' => 'mem-functions.c' Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-10-19 20:40 +0200
Re: [PATCH 04/14] perf/bench: Rename 'mem-memcpy.c' => 'mem-functions.c' Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-10-19 20:40 +0200
[tip:perf/core] perf bench: Rename 'mem-memcpy.c' => ' mem-functions.c' tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 03/14] perf/bench: Eliminate unused argument from bench_mem_common() Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:20 +0200
[tip:perf/core] perf bench: Eliminate unused argument from bench_mem_common() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
[PATCH 01/14] perf/bench: Improve the 'perf bench mem memcpy' code readability Ingo Molnar <mingo@kernel.org> - 2015-10-19 10:20 +0200
[tip:perf/core] perf bench: Improve the 'perf bench mem memcpy' code readability tip-bot for Ingo Molnar <tipbot@zytor.com> - 2015-10-20 09:50 +0200
Re: [PATCH 00/14] perf bench: Misc improvements David Ahern <dsahern@gmail.com> - 2015-10-19 15:50 +0200
Re: [PATCH 00/14] perf bench: Misc improvements Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-10-19 21:10 +0200
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