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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
commit4352b8aee98005853aa63f57d6377282de17a33f (patch)
tree27614d7a9ef05c32d089004e104364ce42324837 /tools/perf/bench/futex-requeue.c
downloadlinux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz
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Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
Diffstat (limited to 'tools/perf/bench/futex-requeue.c')
-rw-r--r--tools/perf/bench/futex-requeue.c319
1 files changed, 319 insertions, 0 deletions
diff --git a/tools/perf/bench/futex-requeue.c b/tools/perf/bench/futex-requeue.c
new file mode 100644
index 000000000..0748b0fd6
--- /dev/null
+++ b/tools/perf/bench/futex-requeue.c
@@ -0,0 +1,319 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com>
+ *
+ * futex-requeue: Block a bunch of threads on futex1 and requeue them
+ * on futex2, N at a time.
+ *
+ * This program is particularly useful to measure the latency of nthread
+ * requeues without waking up any tasks (in the non-pi case) -- thus
+ * mimicking a regular futex_wait.
+ */
+
+/* For the CLR_() macros */
+#include <string.h>
+#include <pthread.h>
+
+#include <signal.h>
+#include "../util/mutex.h"
+#include "../util/stat.h"
+#include <subcmd/parse-options.h>
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/time64.h>
+#include <errno.h>
+#include <perf/cpumap.h>
+#include "bench.h"
+#include "futex.h"
+
+#include <err.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+
+static u_int32_t futex1 = 0, futex2 = 0;
+
+static pthread_t *worker;
+static bool done = false;
+static struct mutex thread_lock;
+static struct cond thread_parent, thread_worker;
+static struct stats requeuetime_stats, requeued_stats;
+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.
+ */
+ .nrequeue = 1,
+};
+
+static const struct option options[] = {
+ OPT_INTEGER( 'b', "buckets", &params.nbuckets, "Specify amount of hash buckets"),
+ OPT_UINTEGER('t', "threads", &params.nthreads, "Specify amount of threads"),
+ OPT_UINTEGER('q', "nrequeue", &params.nrequeue, "Specify amount of threads to requeue at once"),
+ OPT_BOOLEAN( 's', "silent", &params.silent, "Silent mode: do not display data/details"),
+ OPT_BOOLEAN( 'S', "shared", &params.fshared, "Use shared futexes instead of private ones"),
+ OPT_BOOLEAN( 'm', "mlockall", &params.mlockall, "Lock all current and future memory"),
+ OPT_BOOLEAN( 'B', "broadcast", &params.broadcast, "Requeue all threads at once"),
+ OPT_BOOLEAN( 'p', "pi", &params.pi, "Use PI-aware variants of FUTEX_CMP_REQUEUE"),
+
+ OPT_END()
+};
+
+static const char * const bench_futex_requeue_usage[] = {
+ "perf bench futex requeue <options>",
+ NULL
+};
+
+static void print_summary(void)
+{
+ double requeuetime_avg = avg_stats(&requeuetime_stats);
+ double requeuetime_stddev = stddev_stats(&requeuetime_stats);
+ unsigned int requeued_avg = avg_stats(&requeued_stats);
+
+ printf("Requeued %d of %d threads in %.4f ms (+-%.2f%%)\n",
+ requeued_avg,
+ params.nthreads,
+ requeuetime_avg / USEC_PER_MSEC,
+ rel_stddev_stats(requeuetime_stddev, requeuetime_avg));
+ futex_print_nbuckets(&params);
+}
+
+static void *workerfn(void *arg __maybe_unused)
+{
+ int ret;
+
+ mutex_lock(&thread_lock);
+ threads_starting--;
+ if (!threads_starting)
+ cond_signal(&thread_parent);
+ cond_wait(&thread_worker, &thread_lock);
+ mutex_unlock(&thread_lock);
+
+ while (1) {
+ if (!params.pi) {
+ ret = futex_wait(&futex1, 0, NULL, futex_flag);
+ if (!ret)
+ break;
+
+ if (ret && errno != EAGAIN) {
+ if (!params.silent)
+ warnx("futex_wait");
+ break;
+ }
+ } else {
+ ret = futex_wait_requeue_pi(&futex1, 0, &futex2,
+ NULL, futex_flag);
+ if (!ret) {
+ /* got the lock at futex2 */
+ futex_unlock_pi(&futex2, futex_flag);
+ break;
+ }
+
+ if (ret && errno != EAGAIN) {
+ if (!params.silent)
+ warnx("futex_wait_requeue_pi");
+ break;
+ }
+ }
+ }
+
+ return NULL;
+}
+
+static void block_threads(pthread_t *w, struct perf_cpu_map *cpu)
+{
+ cpu_set_t *cpuset;
+ unsigned int i;
+ int nrcpus = cpu__max_cpu().cpu;
+ size_t size;
+
+ threads_starting = params.nthreads;
+
+ cpuset = CPU_ALLOC(nrcpus);
+ BUG_ON(!cpuset);
+ size = CPU_ALLOC_SIZE(nrcpus);
+
+ /* create and block all threads */
+ for (i = 0; i < params.nthreads; i++) {
+ pthread_attr_t thread_attr;
+
+ pthread_attr_init(&thread_attr);
+ CPU_ZERO_S(size, cpuset);
+ CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu, size, cpuset);
+
+ if (pthread_attr_setaffinity_np(&thread_attr, size, cpuset)) {
+ CPU_FREE(cpuset);
+ err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
+ }
+
+ if (pthread_create(&w[i], &thread_attr, workerfn, NULL)) {
+ CPU_FREE(cpuset);
+ err(EXIT_FAILURE, "pthread_create");
+ }
+ pthread_attr_destroy(&thread_attr);
+ }
+ CPU_FREE(cpuset);
+}
+
+static void toggle_done(int sig __maybe_unused,
+ siginfo_t *info __maybe_unused,
+ void *uc __maybe_unused)
+{
+ done = true;
+}
+
+int bench_futex_requeue(int argc, const char **argv)
+{
+ int ret = 0;
+ unsigned int i, j;
+ struct sigaction act;
+ struct perf_cpu_map *cpu;
+
+ argc = parse_options(argc, argv, options, bench_futex_requeue_usage, 0);
+ if (argc)
+ goto err;
+
+ cpu = perf_cpu_map__new_online_cpus();
+ if (!cpu)
+ err(EXIT_FAILURE, "cpu_map__new");
+
+ memset(&act, 0, sizeof(act));
+ sigfillset(&act.sa_mask);
+ act.sa_sigaction = toggle_done;
+ sigaction(SIGINT, &act, NULL);
+
+ if (params.mlockall) {
+ if (mlockall(MCL_CURRENT | MCL_FUTURE))
+ err(EXIT_FAILURE, "mlockall");
+ }
+
+ if (!params.nthreads)
+ params.nthreads = perf_cpu_map__nr(cpu);
+
+ worker = calloc(params.nthreads, sizeof(*worker));
+ if (!worker)
+ err(EXIT_FAILURE, "calloc");
+
+ if (!params.fshared)
+ futex_flag = FUTEX_PRIVATE_FLAG;
+
+ if (params.nrequeue > params.nthreads)
+ params.nrequeue = params.nthreads;
+
+ if (params.broadcast)
+ params.nrequeue = params.nthreads;
+
+ futex_set_nbuckets_param(&params);
+
+ 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,
+ params.pi ? "PI ": "", &futex2, params.nrequeue);
+
+ init_stats(&requeued_stats);
+ init_stats(&requeuetime_stats);
+ mutex_init(&thread_lock);
+ cond_init(&thread_parent);
+ cond_init(&thread_worker);
+
+ for (j = 0; j < bench_repeat && !done; j++) {
+ unsigned int nrequeued = 0, wakeups = 0;
+ struct timeval start, end, runtime;
+
+ /* create, launch & block all threads */
+ block_threads(worker, cpu);
+
+ /* make sure all threads are already blocked */
+ mutex_lock(&thread_lock);
+ while (threads_starting)
+ cond_wait(&thread_parent, &thread_lock);
+ cond_broadcast(&thread_worker);
+ mutex_unlock(&thread_lock);
+
+ usleep(100000);
+
+ /* Ok, all threads are patiently blocked, start requeueing */
+ gettimeofday(&start, NULL);
+ while (nrequeued < params.nthreads) {
+ int r;
+
+ /*
+ * For the regular non-pi case, do not wakeup any tasks
+ * blocked on futex1, allowing us to really measure
+ * futex_wait functionality. For the PI case the first
+ * waiter is always awoken.
+ */
+ if (!params.pi) {
+ r = futex_cmp_requeue(&futex1, 0, &futex2, 0,
+ params.nrequeue,
+ futex_flag);
+ } else {
+ r = futex_cmp_requeue_pi(&futex1, 0, &futex2,
+ params.nrequeue,
+ futex_flag);
+ wakeups++; /* assume no error */
+ }
+
+ if (r < 0)
+ err(EXIT_FAILURE, "couldn't requeue from %p to %p",
+ &futex1, &futex2);
+
+ nrequeued += r;
+ }
+
+ gettimeofday(&end, NULL);
+ timersub(&end, &start, &runtime);
+
+ update_stats(&requeued_stats, nrequeued);
+ update_stats(&requeuetime_stats, runtime.tv_usec);
+
+ if (!params.silent) {
+ if (!params.pi)
+ printf("[Run %d]: Requeued %d of %d threads in "
+ "%.4f ms\n", j + 1, nrequeued,
+ params.nthreads,
+ runtime.tv_usec / (double)USEC_PER_MSEC);
+ else {
+ nrequeued -= wakeups;
+ printf("[Run %d]: Awoke and Requeued (%d+%d) of "
+ "%d threads in %.4f ms\n",
+ j + 1, wakeups, nrequeued,
+ params.nthreads,
+ runtime.tv_usec / (double)USEC_PER_MSEC);
+ }
+
+ }
+
+ if (!params.pi) {
+ /* everybody should be blocked on futex2, wake'em up */
+ nrequeued = futex_wake(&futex2, nrequeued, futex_flag);
+ if (params.nthreads != nrequeued)
+ warnx("couldn't wakeup all tasks (%d/%d)",
+ nrequeued, params.nthreads);
+ }
+
+ for (i = 0; i < params.nthreads; i++) {
+ ret = pthread_join(worker[i], NULL);
+ if (ret)
+ err(EXIT_FAILURE, "pthread_join");
+ }
+ }
+
+ /* cleanup & report results */
+ cond_destroy(&thread_parent);
+ cond_destroy(&thread_worker);
+ mutex_destroy(&thread_lock);
+
+ print_summary();
+
+ free(worker);
+ perf_cpu_map__put(cpu);
+ return ret;
+err:
+ usage_with_options(bench_futex_requeue_usage, options);
+ exit(EXIT_FAILURE);
+}