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From: Dirk Gouders <dirk@gouders.net>
To: Namhyung Kim <namhyung@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Dirk Gouders <dirk@gouders.net>, Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
LKML <linux-kernel@vger.kernel.org>, linux-perf-users@vger.kernel.org
Subject: [PATCH v2 3/3] perf bench sched pipe: introduce multipliers for
number of processes
Date: Sat, 5 Apr 2025 14:00:08 +0200
Message-ID: <20250405120039.15953-4-dirk@gouders.net>
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Introduce multipliers to specify the number of processes to run:
K|K|m|M: multiply leading number by 2^10 or 2^20, respectively
p|P: multiply intermediate result by number of online processors
Examples:
-p 2K =3D 2048
-p 10p =3D 10 * number of online processors
-p 1kp =3D 1024 * number of online processors
Signed-off-by: Dirk Gouders <dirk@gouders.net>
---
tools/perf/Documentation/perf-bench.txt | 14 ++++++
tools/perf/bench/sched-pipe.c | 36 ++++++++++++++-
tools/perf/util/string.c | 58 +++++++++++++++++++++++++
tools/perf/util/string2.h | 1 +
4 files changed, 107 insertions(+), 2 deletions(-)
diff --git a/tools/perf/Documentation/perf-bench.txt b/tools/perf/Documenta=
tion/perf-bench.txt
index 6f7df3d47821..a2a44d80ee26 100644
--- a/tools/perf/Documentation/perf-bench.txt
+++ b/tools/perf/Documentation/perf-bench.txt
@@ -159,6 +159,20 @@ by
-p::
--nprocs=3D::
Number of processes to use for sending tokens along the pipes.
+This option accepts a number follwed by optional (case insensitive)
+multipliers in this order:
+
+- k, m
++
+Multipliers 1024 and 1048576 for the leading number.
+
+- p
++
+Multiplier replaced by the number of online processors.
+
+Example:
+
+ -p 1kP means: 1024 * number of online processors
=20
Example of *pipe*
^^^^^^^^^^^^^^^^^
diff --git a/tools/perf/bench/sched-pipe.c b/tools/perf/bench/sched-pipe.c
index 3c76e8249a9b..a1fa7ad7ed67 100644
--- a/tools/perf/bench/sched-pipe.c
+++ b/tools/perf/bench/sched-pipe.c
@@ -12,7 +12,8 @@
#include <subcmd/parse-options.h>
#include <api/fs/fs.h>
#include "bench.h"
-#include "util/cgroup.h"
+#include <util/cgroup.h>
+#include <util/string2.h>
=20
#include <unistd.h>
#include <stdio.h>
@@ -45,6 +46,8 @@ struct thread_data {
#define LOOPS_DEFAULT 1000000
static unsigned int loops =3D LOOPS_DEFAULT;
=20
+static const char *nproc_str; /* String that specifies a number of process=
es. */
+
/* Use processes by default: */
static bool threaded;
static unsigned int nr_threads =3D 2;
@@ -90,7 +93,8 @@ static int parse_two_cgroups(const struct option *opt __m=
aybe_unused,
=20
static const struct option options[] =3D {
OPT_BOOLEAN('n', "nonblocking", &nonblocking, "Use non-blocking operation=
s"),
- OPT_UINTEGER('p', "nprocs", &nr_threads, "Number of processes"),
+ OPT_STRING('p', "nprocs", &nproc_str, "2P",
+ "Number of processes (2P :=3D 2 * online processors)"),
OPT_UINTEGER('l', "loop", &loops, "Specify number of loops"),
OPT_BOOLEAN('K', "Kn", &Kn_mode, "Send tokens in a complete graph instea=
d of a ring."),
OPT_BOOLEAN('T', "threaded", &threaded, "Specify threads/process based ta=
sk setup"),
@@ -281,6 +285,31 @@ static void *worker_thread_ring(void *__tdata)
/* Ring mode is the default. */
void * (*worker_thread)(void *) =3D worker_thread_ring;
=20
+/*
+ * Get number of processes from the given string,
+ * e.g. "1k" =3D> 1024 or
+ * "8p" =3D> 8 * number of online processors.
+ */
+static unsigned int get_nprocs(const char *np_str)
+{
+ unsigned int np;
+
+ np =3D perf_nptou(np_str);
+
+ if (np =3D=3D -1U) {
+ fprintf(stderr, "Cannot parse number of processes/threads: %s\n",
+ nproc_str);
+ exit(1);
+ }
+
+ if (np < 2) {
+ fprintf(stderr, "Two processes are the minimum requirement.\n");
+ exit(1);
+ }
+
+ return np;
+}
+
static struct thread_data *create_thread_data(void)
{
struct thread_data *threads;
@@ -329,6 +358,9 @@ int bench_sched_pipe(int argc, const char **argv)
=20
argc =3D parse_options(argc, argv, options, bench_sched_pipe_usage, 0);
=20
+ if (nproc_str)
+ nr_threads =3D get_nprocs(nproc_str);
+
if (Kn_mode)
worker_thread =3D worker_thread_kn;
=20
diff --git a/tools/perf/util/string.c b/tools/perf/util/string.c
index c0e927bbadf6..72deb3df9c99 100644
--- a/tools/perf/util/string.c
+++ b/tools/perf/util/string.c
@@ -3,6 +3,7 @@
#include <linux/kernel.h>
#include <linux/string.h>
#include <stdlib.h>
+#include <unistd.h>
=20
#include <linux/ctype.h>
=20
@@ -68,6 +69,63 @@ s64 perf_atoll(const char *str)
return -1;
}
=20
+/*
+ * perf_nptou()
+ *
+ * Parse given string to a number of processes and return that number.
+ * Multipliers up to 'm' are accepted, and an optional final unit suffix
+ * 'p' meaning "number of online processors".
+ *
+ * str must match: (\d+)(k|K|m|M)?(p|P)?
+ *
+ * (e.g. "8P" meaning "8 * number of online processors",
+ * or "1k" meaning "1024",
+ * or "1Kp" meaning "1024 * number of online processors")
+ */
+u32 perf_nptou(const char *str)
+{
+ s32 length;
+ char *p;
+ char c;
+
+ if (!isdigit(str[0]))
+ goto out_err;
+
+ length =3D strtol(str, &p, 10);
+
+ switch (c =3D *p++) {
+ case 'p': case 'P':
+ if (*p)
+ goto out_err;
+ goto handle_p;
+ case '\0':
+ return length;
+ default:
+ goto out_err;
+
+ /* Multipliers */
+ case 'k': case 'K':
+ length <<=3D 10;
+ break;
+ case 'm': case 'M':
+ length <<=3D 20;
+ break;
+ }
+
+ if (*p =3D=3D '\0')
+ return length;
+
+ if (strcmp(p, "p") !=3D 0 && strcmp(p, "P") !=3D 0)
+ goto out_err;
+
+handle_p:
+ length *=3D sysconf(_SC_NPROCESSORS_ONLN);
+ return length;
+
+out_err:
+ return -1U;
+}
+
/* Character class matching */
static bool __match_charclass(const char *pat, char c, const char **npat)
{
diff --git a/tools/perf/util/string2.h b/tools/perf/util/string2.h
index 4c8bff47cfd3..bca2c1687924 100644
--- a/tools/perf/util/string2.h
+++ b/tools/perf/util/string2.h
@@ -12,6 +12,7 @@ extern const char *graph_dotted_line;
extern const char *dots;
=20
s64 perf_atoll(const char *str);
+u32 perf_nptou(const char *str);
bool strglobmatch(const char *str, const char *pat);
bool strglobmatch_nocase(const char *str, const char *pat);
bool strlazymatch(const char *str, const char *pat);
--=20
2.45.3