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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-wake-parallel.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-wake-parallel.c')
-rw-r--r--tools/perf/bench/futex-wake-parallel.c356
1 files changed, 356 insertions, 0 deletions
diff --git a/tools/perf/bench/futex-wake-parallel.c b/tools/perf/bench/futex-wake-parallel.c
new file mode 100644
index 000000000..6aede7c46
--- /dev/null
+++ b/tools/perf/bench/futex-wake-parallel.c
@@ -0,0 +1,356 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015 Davidlohr Bueso.
+ *
+ * Block a bunch of threads and let parallel waker threads wakeup an
+ * equal amount of them. The program output reflects the avg latency
+ * for each individual thread to service its share of work. Ultimately
+ * it can be used to measure futex_wake() changes.
+ */
+#include "bench.h"
+#include <linux/compiler.h>
+#include "../util/debug.h"
+#include "../util/mutex.h"
+
+#ifndef HAVE_PTHREAD_BARRIER
+int bench_futex_wake_parallel(int argc __maybe_unused, const char **argv __maybe_unused)
+{
+ pr_err("%s: pthread_barrier_t unavailable, disabling this test...\n", __func__);
+ return 0;
+}
+#else /* HAVE_PTHREAD_BARRIER */
+/* For the CLR_() macros */
+#include <string.h>
+#include <pthread.h>
+
+#include <signal.h>
+#include "../util/stat.h"
+#include <subcmd/parse-options.h>
+#include <linux/kernel.h>
+#include <linux/time64.h>
+#include <errno.h>
+#include "futex.h"
+#include <perf/cpumap.h>
+
+#include <err.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+
+struct thread_data {
+ pthread_t worker;
+ unsigned int nwoken;
+ struct timeval runtime;
+};
+
+static unsigned int nwakes = 1;
+
+/* all threads will block on the same futex -- hash bucket chaos ;) */
+static u_int32_t futex = 0;
+
+static pthread_t *blocked_worker;
+static bool done = false;
+static struct mutex thread_lock;
+static struct cond thread_parent, thread_worker;
+static pthread_barrier_t barrier;
+static struct stats waketime_stats, wakeup_stats;
+static unsigned int threads_starting;
+static int futex_flag = 0;
+
+static struct bench_futex_parameters params = {
+ .nbuckets = -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('w', "nwakers", &params.nwakes, "Specify amount of waking threads"),
+ 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_END()
+};
+
+static const char * const bench_futex_wake_parallel_usage[] = {
+ "perf bench futex wake-parallel <options>",
+ NULL
+};
+
+static void *waking_workerfn(void *arg)
+{
+ struct thread_data *waker = (struct thread_data *) arg;
+ struct timeval start, end;
+
+ pthread_barrier_wait(&barrier);
+
+ gettimeofday(&start, NULL);
+
+ waker->nwoken = futex_wake(&futex, nwakes, futex_flag);
+ if (waker->nwoken != nwakes)
+ warnx("couldn't wakeup all tasks (%d/%d)",
+ waker->nwoken, nwakes);
+
+ gettimeofday(&end, NULL);
+ timersub(&end, &start, &waker->runtime);
+
+ pthread_exit(NULL);
+ return NULL;
+}
+
+static void wakeup_threads(struct thread_data *td)
+{
+ unsigned int i;
+ pthread_attr_t thread_attr;
+
+ pthread_attr_init(&thread_attr);
+ pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_JOINABLE);
+
+ pthread_barrier_init(&barrier, NULL, params.nwakes + 1);
+
+ /* create and block all threads */
+ for (i = 0; i < params.nwakes; i++) {
+ /*
+ * Thread creation order will impact per-thread latency
+ * as it will affect the order to acquire the hb spinlock.
+ * For now let the scheduler decide.
+ */
+ if (pthread_create(&td[i].worker, &thread_attr,
+ waking_workerfn, (void *)&td[i]))
+ err(EXIT_FAILURE, "pthread_create");
+ }
+
+ pthread_barrier_wait(&barrier);
+
+ for (i = 0; i < params.nwakes; i++)
+ if (pthread_join(td[i].worker, NULL))
+ err(EXIT_FAILURE, "pthread_join");
+
+ pthread_barrier_destroy(&barrier);
+ pthread_attr_destroy(&thread_attr);
+}
+
+static void *blocked_workerfn(void *arg __maybe_unused)
+{
+ 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) { /* handle spurious wakeups */
+ if (futex_wait(&futex, 0, NULL, futex_flag) != EINTR)
+ break;
+ }
+
+ pthread_exit(NULL);
+ 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, blocked_workerfn, NULL)) {
+ CPU_FREE(cpuset);
+ err(EXIT_FAILURE, "pthread_create");
+ }
+ pthread_attr_destroy(&thread_attr);
+ }
+ CPU_FREE(cpuset);
+}
+
+static void print_run(struct thread_data *waking_worker, unsigned int run_num)
+{
+ unsigned int i, wakeup_avg;
+ double waketime_avg, waketime_stddev;
+ struct stats __waketime_stats, __wakeup_stats;
+
+ init_stats(&__wakeup_stats);
+ init_stats(&__waketime_stats);
+
+ for (i = 0; i < params.nwakes; i++) {
+ update_stats(&__waketime_stats, waking_worker[i].runtime.tv_usec);
+ update_stats(&__wakeup_stats, waking_worker[i].nwoken);
+ }
+
+ waketime_avg = avg_stats(&__waketime_stats);
+ waketime_stddev = stddev_stats(&__waketime_stats);
+ wakeup_avg = avg_stats(&__wakeup_stats);
+
+ printf("[Run %d]: Avg per-thread latency (waking %d/%d threads) "
+ "in %.4f ms (+-%.2f%%)\n", run_num + 1, wakeup_avg,
+ params.nthreads, waketime_avg / USEC_PER_MSEC,
+ rel_stddev_stats(waketime_stddev, waketime_avg));
+}
+
+static void print_summary(void)
+{
+ unsigned int wakeup_avg;
+ double waketime_avg, waketime_stddev;
+
+ waketime_avg = avg_stats(&waketime_stats);
+ waketime_stddev = stddev_stats(&waketime_stats);
+ wakeup_avg = avg_stats(&wakeup_stats);
+
+ printf("Avg per-thread latency (waking %d/%d threads) in %.4f ms (+-%.2f%%)\n",
+ wakeup_avg,
+ params.nthreads,
+ waketime_avg / USEC_PER_MSEC,
+ rel_stddev_stats(waketime_stddev, waketime_avg));
+ futex_print_nbuckets(&params);
+}
+
+
+static void do_run_stats(struct thread_data *waking_worker)
+{
+ unsigned int i;
+
+ for (i = 0; i < params.nwakes; i++) {
+ update_stats(&waketime_stats, waking_worker[i].runtime.tv_usec);
+ update_stats(&wakeup_stats, waking_worker[i].nwoken);
+ }
+
+}
+
+static void toggle_done(int sig __maybe_unused,
+ siginfo_t *info __maybe_unused,
+ void *uc __maybe_unused)
+{
+ done = true;
+}
+
+int bench_futex_wake_parallel(int argc, const char **argv)
+{
+ int ret = 0;
+ unsigned int i, j;
+ struct sigaction act;
+ struct thread_data *waking_worker;
+ struct perf_cpu_map *cpu;
+
+ argc = parse_options(argc, argv, options,
+ bench_futex_wake_parallel_usage, 0);
+ if (argc) {
+ usage_with_options(bench_futex_wake_parallel_usage, options);
+ exit(EXIT_FAILURE);
+ }
+
+ 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");
+ }
+
+ cpu = perf_cpu_map__new_online_cpus();
+ if (!cpu)
+ err(EXIT_FAILURE, "calloc");
+
+ if (!params.nthreads)
+ params.nthreads = perf_cpu_map__nr(cpu);
+
+ /* some sanity checks */
+ if (params.nwakes > params.nthreads ||
+ !params.nwakes)
+ params.nwakes = params.nthreads;
+
+ if (params.nthreads % params.nwakes)
+ errx(EXIT_FAILURE, "Must be perfectly divisible");
+ /*
+ * Each thread will wakeup nwakes tasks in
+ * a single futex_wait call.
+ */
+ nwakes = params.nthreads/params.nwakes;
+
+ blocked_worker = calloc(params.nthreads, sizeof(*blocked_worker));
+ if (!blocked_worker)
+ err(EXIT_FAILURE, "calloc");
+
+ if (!params.fshared)
+ futex_flag = FUTEX_PRIVATE_FLAG;
+
+ futex_set_nbuckets_param(&params);
+
+ 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",
+ &futex, params.nwakes, nwakes);
+
+ init_stats(&wakeup_stats);
+ init_stats(&waketime_stats);
+
+ mutex_init(&thread_lock);
+ cond_init(&thread_parent);
+ cond_init(&thread_worker);
+
+ for (j = 0; j < bench_repeat && !done; j++) {
+ waking_worker = calloc(params.nwakes, sizeof(*waking_worker));
+ if (!waking_worker)
+ err(EXIT_FAILURE, "calloc");
+
+ /* create, launch & block all threads */
+ block_threads(blocked_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(200000);
+
+ /* Ok, all threads are patiently blocked, start waking folks up */
+ wakeup_threads(waking_worker);
+
+ for (i = 0; i < params.nthreads; i++) {
+ ret = pthread_join(blocked_worker[i], NULL);
+ if (ret)
+ err(EXIT_FAILURE, "pthread_join");
+ }
+
+ do_run_stats(waking_worker);
+ if (!params.silent)
+ print_run(waking_worker, j);
+
+ free(waking_worker);
+ }
+
+ /* cleanup & report results */
+ cond_destroy(&thread_parent);
+ cond_destroy(&thread_worker);
+ mutex_destroy(&thread_lock);
+
+ print_summary();
+
+ free(blocked_worker);
+ perf_cpu_map__put(cpu);
+ return ret;
+}
+#endif /* HAVE_PTHREAD_BARRIER */