/*
 * Copyright (C) 2013  Davidlohr Bueso <davidlohr@hp.com>
 *
 * futex-hash: Stress the hell out of the Linux kernel futex uaddr hashing.
 *
 * This program is particularly useful for measuring the kernel's futex hash
 * table/function implementation. In order for it to make sense, use with as
 * many threads and futexes as possible.
 */

/* For the CLR_() macros */
#include <pthread.h>

#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <sys/time.h>

#include "../util/stat.h"
#include <subcmd/parse-options.h>
#include "bench.h"
#include "futex.h"

#include <err.h>
#include <sys/time.h>

static unsigned int nthreads = 0;
static unsigned int nsecs    = 10;
/* amount of futexes per thread */
static unsigned int nfutexes = 1024;
static bool fshared = false, done = false, silent = false;
static int futex_flag = 0;

struct timeval start, end, runtime;
static pthread_mutex_t thread_lock;
static unsigned int threads_starting;
static struct stats throughput_stats;
static pthread_cond_t thread_parent, thread_worker;

struct worker {
	int tid;
	u_int32_t *futex;
	pthread_t thread;
	unsigned long ops;
};

static const struct option options[] = {
	OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
	OPT_UINTEGER('r', "runtime", &nsecs,    "Specify runtime (in seconds)"),
	OPT_UINTEGER('f', "futexes", &nfutexes, "Specify amount of futexes per threads"),
	OPT_BOOLEAN( 's', "silent",  &silent,   "Silent mode: do not display data/details"),
	OPT_BOOLEAN( 'S', "shared",  &fshared,  "Use shared futexes instead of private ones"),
	OPT_END()
};

static const char * const bench_futex_hash_usage[] = {
	"perf bench futex hash <options>",
	NULL
};

static void *workerfn(void *arg)
{
	int ret;
	struct worker *w = (struct worker *) arg;
	unsigned int i;
	unsigned long ops = w->ops; /* avoid cacheline bouncing */

	pthread_mutex_lock(&thread_lock);
	threads_starting--;
	if (!threads_starting)
		pthread_cond_signal(&thread_parent);
	pthread_cond_wait(&thread_worker, &thread_lock);
	pthread_mutex_unlock(&thread_lock);

	do {
		for (i = 0; i < nfutexes; i++, ops++) {
			/*
			 * We want the futex calls to fail in order to stress
			 * the hashing of uaddr and not measure other steps,
			 * such as internal waitqueue handling, thus enlarging
			 * the critical region protected by hb->lock.
			 */
			ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag);
			if (!silent &&
			    (!ret || errno != EAGAIN || errno != EWOULDBLOCK))
				warn("Non-expected futex return call");
		}
	}  while (!done);

	w->ops = ops;
	return NULL;
}

static void toggle_done(int sig __maybe_unused,
			siginfo_t *info __maybe_unused,
			void *uc __maybe_unused)
{
	/* inform all threads that we're done for the day */
	done = true;
	gettimeofday(&end, NULL);
	timersub(&end, &start, &runtime);
}

static void print_summary(void)
{
	unsigned long avg = avg_stats(&throughput_stats);
	double stddev = stddev_stats(&throughput_stats);

	printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
	       !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
	       (int) runtime.tv_sec);
}

int bench_futex_hash(int argc, const char **argv,
		     const char *prefix __maybe_unused)
{
	int ret = 0;
	cpu_set_t cpu;
	struct sigaction act;
	unsigned int i, ncpus;
	pthread_attr_t thread_attr;
	struct worker *worker = NULL;

	argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0);
	if (argc) {
		usage_with_options(bench_futex_hash_usage, options);
		exit(EXIT_FAILURE);
	}

	ncpus = sysconf(_SC_NPROCESSORS_ONLN);
	nsecs = futexbench_sanitize_numeric(nsecs);
	nfutexes = futexbench_sanitize_numeric(nfutexes);

	sigfillset(&act.sa_mask);
	act.sa_sigaction = toggle_done;
	sigaction(SIGINT, &act, NULL);

	if (!nthreads) /* default to the number of CPUs */
		nthreads = ncpus;
	else
		nthreads = futexbench_sanitize_numeric(nthreads);

	worker = calloc(nthreads, sizeof(*worker));
	if (!worker)
		goto errmem;

	if (!fshared)
		futex_flag = FUTEX_PRIVATE_FLAG;

	printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
	       getpid(), nthreads, nfutexes, fshared ? "shared":"private", nsecs);

	init_stats(&throughput_stats);
	pthread_mutex_init(&thread_lock, NULL);
	pthread_cond_init(&thread_parent, NULL);
	pthread_cond_init(&thread_worker, NULL);

	threads_starting = nthreads;
	pthread_attr_init(&thread_attr);
	gettimeofday(&start, NULL);
	for (i = 0; i < nthreads; i++) {
		worker[i].tid = i;
		worker[i].futex = calloc(nfutexes, sizeof(*worker[i].futex));
		if (!worker[i].futex)
			goto errmem;

		CPU_ZERO(&cpu);
		CPU_SET(i % ncpus, &cpu);

		ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu);
		if (ret)
			err(EXIT_FAILURE, "pthread_attr_setaffinity_np");

		ret = pthread_create(&worker[i].thread, &thread_attr, workerfn,
				     (void *)(struct worker *) &worker[i]);
		if (ret)
			err(EXIT_FAILURE, "pthread_create");

	}
	pthread_attr_destroy(&thread_attr);

	pthread_mutex_lock(&thread_lock);
	while (threads_starting)
		pthread_cond_wait(&thread_parent, &thread_lock);
	pthread_cond_broadcast(&thread_worker);
	pthread_mutex_unlock(&thread_lock);

	sleep(nsecs);
	toggle_done(0, NULL, NULL);

	for (i = 0; i < nthreads; i++) {
		ret = pthread_join(worker[i].thread, NULL);
		if (ret)
			err(EXIT_FAILURE, "pthread_join");
	}

	/* cleanup & report results */
	pthread_cond_destroy(&thread_parent);
	pthread_cond_destroy(&thread_worker);
	pthread_mutex_destroy(&thread_lock);

	for (i = 0; i < nthreads; i++) {
		unsigned long t = worker[i].ops/runtime.tv_sec;
		update_stats(&throughput_stats, t);
		if (!silent) {
			if (nfutexes == 1)
				printf("[thread %2d] futex: %p [ %ld ops/sec ]\n",
				       worker[i].tid, &worker[i].futex[0], t);
			else
				printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n",
				       worker[i].tid, &worker[i].futex[0],
				       &worker[i].futex[nfutexes-1], t);
		}

		free(worker[i].futex);
	}

	print_summary();

	free(worker);
	return ret;
errmem:
	err(EXIT_FAILURE, "calloc");
}
mit-subject'>tracing: Fix hwlat kthread migration</div><div class='commit-msg'>The hwlat tracer creates a kernel thread at start of the tracer. It is
pinned to a single CPU and will move to the next CPU after each period of
running. If the user modifies the migration thread's affinity, it will not
change after that happens.

The original code created the thread at the first instance it was called,
but later was changed to destroy the thread after the tracer was finished,
and would not be created until the next instance of the tracer was
established. The code that initialized the affinity was only called on the
initial instantiation of the tracer. After that, it was not initialized, and
the previous affinity did not match the current newly created one, making
it appear that the user modified the thread's affinity when it did not, and
the thread failed to migrate again.

Cc: stable@vger.kernel.org
Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Steven Rostedt (VMware) &lt;rostedt@goodmis.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=79c6f448c8b79c321e4a1f31f98194e4f6b6cae7'>Diffstat</a> (limited to 'drivers/usb/dwc3/dwc3-keystone.c')</div><table summary='diffstat' class='diffstat'>