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Message-ID: <20251207085741.1388141-1-namhyung@kernel.org>
Date: Sun, 7 Dec 2025 00:57:41 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
Ian Rogers <irogers@...gle.com>,
James Clark <james.clark@...aro.org>
Cc: Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org,
Ankur Arora <ankur.a.arora@...cle.com>
Subject: [PATCH] perf bench: Add -t/--threads option to perf bench mem mmap
So that it can measure overhead of mmap_lock and/or per-VMA lock
contention.
$ perf bench mem mmap -f demand -l 1000 -t 1
# Running 'mem/mmap' benchmark:
# function 'demand' (Demand loaded mmap())
# Copying 1MB bytes ...
2.914503 GB/sec
$ perf bench mem mmap -f demand -l 1000 -t 2
# Running 'mem/mmap' benchmark:
# function 'demand' (Demand loaded mmap())
# Copying 1MB bytes ...
888.769991 MB/sec
$ perf bench mem mmap -f demand -l 1000 -t 3
# Running 'mem/mmap' benchmark:
# function 'demand' (Demand loaded mmap())
# Copying 1MB bytes ...
757.658220 MB/sec
$ perf bench mem mmap -f demand -l 1000 -t 4
# Running 'mem/mmap' benchmark:
# function 'demand' (Demand loaded mmap())
# Copying 1MB bytes ...
316.410713 MB/sec
Cc: Ankur Arora <ankur.a.arora@...cle.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
tools/perf/Documentation/perf-bench.txt | 4 ++
tools/perf/bench/mem-functions.c | 74 +++++++++++++++++++++----
2 files changed, 67 insertions(+), 11 deletions(-)
diff --git a/tools/perf/Documentation/perf-bench.txt b/tools/perf/Documentation/perf-bench.txt
index 1160224cb718392d..c5913cf59c988421 100644
--- a/tools/perf/Documentation/perf-bench.txt
+++ b/tools/perf/Documentation/perf-bench.txt
@@ -274,6 +274,10 @@ Repeat mmap() invocation this number of times.
--cycles::
Use perf's cpu-cycles event instead of gettimeofday syscall.
+-t::
+--threads=<NUM>::
+Create multiple threads to call mmap/munmap concurrently.
+
SUITES FOR 'numa'
~~~~~~~~~~~~~~~~~
*mem*::
diff --git a/tools/perf/bench/mem-functions.c b/tools/perf/bench/mem-functions.c
index 2908a3a796c932d0..e7e7d0b41fc7720f 100644
--- a/tools/perf/bench/mem-functions.c
+++ b/tools/perf/bench/mem-functions.c
@@ -26,6 +26,7 @@
#include <errno.h>
#include <linux/time64.h>
#include <linux/log2.h>
+#include <pthread.h>
#define K 1024
@@ -41,6 +42,7 @@ static unsigned int nr_loops = 1;
static bool use_cycles;
static int cycles_fd;
static unsigned int seed;
+static unsigned int nr_threads = 1;
static const struct option bench_common_options[] = {
OPT_STRING('s', "size", &size_str, "1MB",
@@ -174,7 +176,7 @@ static void clock_accum(union bench_clock *a, union bench_clock *b)
static double timeval2double(struct timeval *ts)
{
- return (double)ts->tv_sec + (double)ts->tv_usec / (double)USEC_PER_SEC;
+ return (double)ts->tv_sec + (double)ts->tv_usec / (double)USEC_PER_SEC / nr_threads;
}
#define print_bps(x) do { \
@@ -494,16 +496,27 @@ static void mmap_page_touch(void *dst, size_t size, unsigned int page_shift, boo
}
}
-static int do_mmap(const struct function *r, struct bench_params *p,
- void *src __maybe_unused, void *dst __maybe_unused,
- union bench_clock *accum)
+struct mmap_data {
+ pthread_t id;
+ const struct function *func;
+ struct bench_params *params;
+ union bench_clock result;
+ unsigned int seed;
+ int error;
+};
+
+static void *do_mmap_thread(void *arg)
{
+ struct mmap_data *data = arg;
+ const struct function *r = data->func;
+ struct bench_params *p = data->params;
union bench_clock start, end, diff;
mmap_op_t fn = r->fn.mmap_op;
bool populate = strcmp(r->name, "populate") == 0;
+ void *dst;
- if (p->seed)
- srand(p->seed);
+ if (data->seed)
+ srand(data->seed);
for (unsigned int i = 0; i < p->nr_loops; i++) {
clock_get(&start);
@@ -514,16 +527,53 @@ static int do_mmap(const struct function *r, struct bench_params *p,
fn(dst, p->size, p->page_shift, p->seed);
clock_get(&end);
diff = clock_diff(&start, &end);
- clock_accum(accum, &diff);
+ clock_accum(&data->result, &diff);
bench_munmap(dst, p->size);
}
- return 0;
+ return data;
out:
- printf("# Memory allocation failed - maybe size (%s) %s?\n", size_str,
- p->page_shift != PAGE_SHIFT_4KB ? "has insufficient hugepages" : "is too large");
- return -1;
+ data->error = -ENOMEM;
+ return NULL;
+}
+
+static int do_mmap(const struct function *r, struct bench_params *p,
+ void *src __maybe_unused, void *dst __maybe_unused,
+ union bench_clock *accum)
+{
+ struct mmap_data *data;
+ int error = 0;
+
+ data = calloc(nr_threads, sizeof(*data));
+ if (!data) {
+ printf("# Failed to allocate thread resources\n");
+ return -1;
+ }
+
+ for (unsigned int i = 0; i < nr_threads; i++) {
+ data[i].func = r;
+ data[i].params = p;
+ if (p->seed)
+ data[i].seed = p->seed + i;
+
+ if (pthread_create(&data[i].id, NULL, do_mmap_thread, &data[i]) < 0)
+ data[i].error = -errno;
+ }
+
+ for (unsigned int i = 0; i < nr_threads; i++) {
+ pthread_join(data[i].id, NULL);
+
+ clock_accum(accum, &data[i].result);
+ error |= data[i].error;
+ }
+ free(data);
+
+ if (error) {
+ printf("# Memory allocation failed - maybe size (%s) %s?\n", size_str,
+ p->page_shift != PAGE_SHIFT_4KB ? "has insufficient hugepages" : "is too large");
+ }
+ return error ? -1 : 0;
}
static const char * const bench_mem_mmap_usage[] = {
@@ -548,6 +598,8 @@ int bench_mem_mmap(int argc, const char **argv)
static const struct option bench_mmap_options[] = {
OPT_UINTEGER('r', "randomize", &seed,
"Seed to randomize page access offset."),
+ OPT_UINTEGER('t', "threads", &nr_threads,
+ "Number of threads to run concurrently (default: 1)."),
OPT_PARENT(bench_common_options),
OPT_END()
};
--
2.52.0.223.gf5cc29aaa4-goog
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