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Message-ID: <20250407155742.968816-19-bigeasy@linutronix.de>
Date: Mon, 7 Apr 2025 17:57:41 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-kernel@...r.kernel.org
Cc: André Almeida <andrealmeid@...lia.com>,
Darren Hart <dvhart@...radead.org>,
Davidlohr Bueso <dave@...olabs.net>,
Ingo Molnar <mingo@...hat.com>,
Juri Lelli <juri.lelli@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Valentin Schneider <vschneid@...hat.com>,
Waiman Long <longman@...hat.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
"Liang, Kan" <kan.liang@...ux.intel.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Jiri Olsa <jolsa@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Namhyung Kim <namhyung@...nel.org>,
linux-perf-users@...r.kernel.org
Subject: [PATCH v11 18/19] tools/perf: Allow to select the number of hash buckets.
Add the -b/ --buckets argument to specify the number of hash buckets for
the private futex hash. This is directly passed to
prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS)
and must return without an error if specified. The size of the private
hash is verified with PR_FUTEX_HASH_GET_SLOTS.
If the PR_FUTEX_HASH_GET_SLOTS failed then it is assumed that an older
kernel was used without the support and that the global hash is used.
Cc: "Liang, Kan" <kan.liang@...ux.intel.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: linux-perf-users@...r.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
tools/perf/bench/Build | 1 +
tools/perf/bench/futex-hash.c | 6 +++
tools/perf/bench/futex-lock-pi.c | 4 ++
tools/perf/bench/futex-requeue.c | 5 +++
tools/perf/bench/futex-wake-parallel.c | 8 +++-
tools/perf/bench/futex-wake.c | 3 ++
tools/perf/bench/futex.c | 58 ++++++++++++++++++++++++++
tools/perf/bench/futex.h | 4 ++
8 files changed, 88 insertions(+), 1 deletion(-)
create mode 100644 tools/perf/bench/futex.c
diff --git a/tools/perf/bench/Build b/tools/perf/bench/Build
index 279ab2ab4abe4..b558ab98719f9 100644
--- a/tools/perf/bench/Build
+++ b/tools/perf/bench/Build
@@ -3,6 +3,7 @@ perf-bench-y += sched-pipe.o
perf-bench-y += sched-seccomp-notify.o
perf-bench-y += syscall.o
perf-bench-y += mem-functions.o
+perf-bench-y += futex.o
perf-bench-y += futex-hash.o
perf-bench-y += futex-wake.o
perf-bench-y += futex-wake-parallel.o
diff --git a/tools/perf/bench/futex-hash.c b/tools/perf/bench/futex-hash.c
index b472eded521b1..c843bd8543c74 100644
--- a/tools/perf/bench/futex-hash.c
+++ b/tools/perf/bench/futex-hash.c
@@ -18,9 +18,11 @@
#include <stdlib.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
+#include <linux/prctl.h>
#include <linux/zalloc.h>
#include <sys/time.h>
#include <sys/mman.h>
+#include <sys/prctl.h>
#include <perf/cpumap.h>
#include "../util/mutex.h"
@@ -50,9 +52,11 @@ struct worker {
static struct bench_futex_parameters params = {
.nfutexes = 1024,
.runtime = 10,
+ .nbuckets = -1,
};
static const struct option options[] = {
+ OPT_INTEGER( 'b', "buckets", ¶ms.nbuckets, "Specify amount of hash buckets"),
OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"),
OPT_UINTEGER('r', "runtime", ¶ms.runtime, "Specify runtime (in seconds)"),
OPT_UINTEGER('f', "futexes", ¶ms.nfutexes, "Specify amount of futexes per threads"),
@@ -118,6 +122,7 @@ static void print_summary(void)
printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
!params.silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
(int)bench__runtime.tv_sec);
+ futex_print_nbuckets(¶ms);
}
int bench_futex_hash(int argc, const char **argv)
@@ -161,6 +166,7 @@ int bench_futex_hash(int argc, const char **argv)
if (!params.fshared)
futex_flag = FUTEX_PRIVATE_FLAG;
+ futex_set_nbuckets_param(¶ms);
printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
getpid(), params.nthreads, params.nfutexes, params.fshared ? "shared":"private", params.runtime);
diff --git a/tools/perf/bench/futex-lock-pi.c b/tools/perf/bench/futex-lock-pi.c
index 0416120c091b2..40640b6744279 100644
--- a/tools/perf/bench/futex-lock-pi.c
+++ b/tools/perf/bench/futex-lock-pi.c
@@ -41,10 +41,12 @@ static struct stats throughput_stats;
static struct cond thread_parent, thread_worker;
static struct bench_futex_parameters params = {
+ .nbuckets = -1,
.runtime = 10,
};
static const struct option options[] = {
+ OPT_INTEGER( 'b', "buckets", ¶ms.nbuckets, "Specify amount of hash buckets"),
OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"),
OPT_UINTEGER('r', "runtime", ¶ms.runtime, "Specify runtime (in seconds)"),
OPT_BOOLEAN( 'M', "multi", ¶ms.multi, "Use multiple futexes"),
@@ -67,6 +69,7 @@ static void print_summary(void)
printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
!params.silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
(int)bench__runtime.tv_sec);
+ futex_print_nbuckets(¶ms);
}
static void toggle_done(int sig __maybe_unused,
@@ -203,6 +206,7 @@ int bench_futex_lock_pi(int argc, const char **argv)
mutex_init(&thread_lock);
cond_init(&thread_parent);
cond_init(&thread_worker);
+ futex_set_nbuckets_param(¶ms);
threads_starting = params.nthreads;
gettimeofday(&bench__start, NULL);
diff --git a/tools/perf/bench/futex-requeue.c b/tools/perf/bench/futex-requeue.c
index aad5bfc4fe188..0748b0fd689e8 100644
--- a/tools/perf/bench/futex-requeue.c
+++ b/tools/perf/bench/futex-requeue.c
@@ -42,6 +42,7 @@ static unsigned int threads_starting;
static int futex_flag = 0;
static struct bench_futex_parameters params = {
+ .nbuckets = -1,
/*
* How many tasks to requeue at a time.
* Default to 1 in order to make the kernel work more.
@@ -50,6 +51,7 @@ static struct bench_futex_parameters params = {
};
static const struct option options[] = {
+ OPT_INTEGER( 'b', "buckets", ¶ms.nbuckets, "Specify amount of hash buckets"),
OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"),
OPT_UINTEGER('q', "nrequeue", ¶ms.nrequeue, "Specify amount of threads to requeue at once"),
OPT_BOOLEAN( 's', "silent", ¶ms.silent, "Silent mode: do not display data/details"),
@@ -77,6 +79,7 @@ static void print_summary(void)
params.nthreads,
requeuetime_avg / USEC_PER_MSEC,
rel_stddev_stats(requeuetime_stddev, requeuetime_avg));
+ futex_print_nbuckets(¶ms);
}
static void *workerfn(void *arg __maybe_unused)
@@ -204,6 +207,8 @@ int bench_futex_requeue(int argc, const char **argv)
if (params.broadcast)
params.nrequeue = params.nthreads;
+ futex_set_nbuckets_param(¶ms);
+
printf("Run summary [PID %d]: Requeuing %d threads (from [%s] %p to %s%p), "
"%d at a time.\n\n", getpid(), params.nthreads,
params.fshared ? "shared":"private", &futex1,
diff --git a/tools/perf/bench/futex-wake-parallel.c b/tools/perf/bench/futex-wake-parallel.c
index 4352e318631e9..6aede7c46b337 100644
--- a/tools/perf/bench/futex-wake-parallel.c
+++ b/tools/perf/bench/futex-wake-parallel.c
@@ -57,9 +57,12 @@ static struct stats waketime_stats, wakeup_stats;
static unsigned int threads_starting;
static int futex_flag = 0;
-static struct bench_futex_parameters params;
+static struct bench_futex_parameters params = {
+ .nbuckets = -1,
+};
static const struct option options[] = {
+ OPT_INTEGER( 'b', "buckets", ¶ms.nbuckets, "Specify amount of hash buckets"),
OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"),
OPT_UINTEGER('w', "nwakers", ¶ms.nwakes, "Specify amount of waking threads"),
OPT_BOOLEAN( 's', "silent", ¶ms.silent, "Silent mode: do not display data/details"),
@@ -218,6 +221,7 @@ static void print_summary(void)
params.nthreads,
waketime_avg / USEC_PER_MSEC,
rel_stddev_stats(waketime_stddev, waketime_avg));
+ futex_print_nbuckets(¶ms);
}
@@ -291,6 +295,8 @@ int bench_futex_wake_parallel(int argc, const char **argv)
if (!params.fshared)
futex_flag = FUTEX_PRIVATE_FLAG;
+ futex_set_nbuckets_param(¶ms);
+
printf("Run summary [PID %d]: blocking on %d threads (at [%s] "
"futex %p), %d threads waking up %d at a time.\n\n",
getpid(), params.nthreads, params.fshared ? "shared":"private",
diff --git a/tools/perf/bench/futex-wake.c b/tools/perf/bench/futex-wake.c
index 49b3c89b0b35d..a31fc1563862e 100644
--- a/tools/perf/bench/futex-wake.c
+++ b/tools/perf/bench/futex-wake.c
@@ -42,6 +42,7 @@ static unsigned int threads_starting;
static int futex_flag = 0;
static struct bench_futex_parameters params = {
+ .nbuckets = -1,
/*
* How many wakeups to do at a time.
* Default to 1 in order to make the kernel work more.
@@ -50,6 +51,7 @@ static struct bench_futex_parameters params = {
};
static const struct option options[] = {
+ OPT_INTEGER( 'b', "buckets", ¶ms.nbuckets, "Specify amount of hash buckets"),
OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"),
OPT_UINTEGER('w', "nwakes", ¶ms.nwakes, "Specify amount of threads to wake at once"),
OPT_BOOLEAN( 's', "silent", ¶ms.silent, "Silent mode: do not display data/details"),
@@ -93,6 +95,7 @@ static void print_summary(void)
params.nthreads,
waketime_avg / USEC_PER_MSEC,
rel_stddev_stats(waketime_stddev, waketime_avg));
+ futex_print_nbuckets(¶ms);
}
static void block_threads(pthread_t *w, struct perf_cpu_map *cpu)
diff --git a/tools/perf/bench/futex.c b/tools/perf/bench/futex.c
new file mode 100644
index 0000000000000..8109d6bf3ede2
--- /dev/null
+++ b/tools/perf/bench/futex.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <linux/prctl.h>
+#include <sys/prctl.h>
+
+#include "futex.h"
+
+void futex_set_nbuckets_param(struct bench_futex_parameters *params)
+{
+ int ret;
+
+ if (params->nbuckets < 0)
+ return;
+
+ ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets);
+ if (ret) {
+ printf("Requesting %d hash buckets failed: %d/%m\n",
+ params->nbuckets, ret);
+ err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
+ }
+}
+
+void futex_print_nbuckets(struct bench_futex_parameters *params)
+{
+ char *futex_hash_mode;
+ int ret;
+
+ ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_SLOTS);
+ if (params->nbuckets >= 0) {
+ if (ret != params->nbuckets) {
+ if (ret < 0) {
+ printf("Can't query number of buckets: %d/%m\n", ret);
+ err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
+ }
+ printf("Requested number of hash buckets does not currently used.\n");
+ printf("Requested: %d in usage: %d\n", params->nbuckets, ret);
+ err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
+ }
+ if (params->nbuckets == 0)
+ ret = asprintf(&futex_hash_mode, "Futex hashing: global hash");
+ else
+ ret = asprintf(&futex_hash_mode, "Futex hashing: %d hash buckets",
+ params->nbuckets);
+ } else {
+ if (ret <= 0) {
+ ret = asprintf(&futex_hash_mode, "Futex hashing: global hash");
+ } else {
+ ret = asprintf(&futex_hash_mode, "Futex hashing: auto resized to %d buckets",
+ ret);
+ }
+ }
+ if (ret < 0)
+ err(EXIT_FAILURE, "ENOMEM, futex_hash_mode");
+ printf("%s\n", futex_hash_mode);
+ free(futex_hash_mode);
+}
diff --git a/tools/perf/bench/futex.h b/tools/perf/bench/futex.h
index ebdc2b032afc1..dd295d27044ac 100644
--- a/tools/perf/bench/futex.h
+++ b/tools/perf/bench/futex.h
@@ -25,6 +25,7 @@ struct bench_futex_parameters {
unsigned int nfutexes;
unsigned int nwakes;
unsigned int nrequeue;
+ int nbuckets;
};
/**
@@ -143,4 +144,7 @@ futex_cmp_requeue_pi(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2,
val, opflags);
}
+void futex_set_nbuckets_param(struct bench_futex_parameters *params);
+void futex_print_nbuckets(struct bench_futex_parameters *params);
+
#endif /* _FUTEX_H */
--
2.49.0
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