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Date: Mon, 16 Apr 2012 08:34:39 +0000
From: "Chen, Dennis (SRDC SW)" <Dennis1.Chen@....com>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: Ingo Molnar <mingo@...nel.org>,
"paulmck@...ux.vnet.ibm.com" <paulmck@...ux.vnet.ibm.com>,
"peterz@...radead.org" <peterz@...radead.org>,
Paul Mackerras <paulus@...ba.org>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Subject: [PATCH 1/2] tools perf: Add a new benchmark tool for semaphore/mutex
A new benchmark tool for semaphore or mutex lock.
Signed-off-by: Dennis Chen <dennis1.chen@....com>
---
diff --git a/tools/perf/bench/lock-mutex.c b/tools/perf/bench/lock-mutex.c
new file mode 100644
index 0000000..4f6edb2
--- /dev/null
+++ b/tools/perf/bench/lock-mutex.c
@@ -0,0 +1,294 @@
+/*
+ * tools/perf/bench/lock-mutex.c
+ *
+ * mutex lock: performance benchmark for semaphore or mutex lock
+ *
+ * Started by Dennis Chen <dennis1.chen@....com>
+ */
+
+#include "../util/util.h"
+#include "../util/parse-options.h"
+#include "../util/header.h"
+#include "bench.h"
+
+#include <sched.h>
+#include <semaphore.h>
+#include <sys/mman.h>
+#include <sys/times.h>
+
+#define NR_TASK 5000UL
+#define PATH_MAX_LEN 256
+/*
+ * 'sys/module' is a good start point as the benchmark target since it has
+ * almost no dependencies on external devices. Although sysfs in the kernel
+ * is in a slow path, we just use it as the semaphore/mutex lock performance
+ * benchmark...
+ */
+
+#define TEST_DIR "/sys/module"
+#define FILE_MODE (S_IRWXU|S_IRWXG|S_IRWXO)
+#define DIR_MODE FILE_MODE
+
+typedef void (*MUTEX_BENCH_FN)(char *);
+
+static unsigned int nr_cpus;
+static unsigned int nr_tasks;
+static bool use_clock;
+static int clock_fd;
+
+static const struct option options[] = {
+ OPT_UINTEGER('p', "cpus", &nr_cpus,
+ "Specify the cpu count in the system. "),
+ OPT_UINTEGER('t', "tasks", &nr_tasks,
+ "Specify the count of tasks will be created."),
+ OPT_BOOLEAN('c', "clock", &use_clock,
+ "Use CPU clock for measuring"),
+ OPT_END()
+};
+
+/* shared data area among tasks to store the perf data*/
+struct mutex_perf_data {
+ struct timeval dur;
+ u64 cpu_cycle;
+ u64 cpu_ins;
+ sem_t sem;
+};
+
+struct mutex_perf_data *sdata;
+
+static void print_usage(void)
+{
+ printf("Usage:\n");
+ printf("perf bench locking mutex -p cpus -t tasks [-c]\n");
+}
+
+static const char * const bench_lock_mutex_usage[] = {
+ "perf bench locking mutex <options>",
+ NULL
+};
+
+static struct perf_event_attr clock_attr = {
+ .type = PERF_TYPE_HARDWARE,
+ .config = PERF_COUNT_HW_CPU_CYCLES
+};
+
+static void init_clock(void)
+{
+ clock_fd = sys_perf_event_open(&clock_attr, getpid(), -1, -1, 0);
+
+ if (clock_fd < 0 && errno == ENOSYS)
+ die("No CONFIG_PERF_EVENTS=y kernel support configured?\n");
+ else
+ BUG_ON(clock_fd < 0);
+}
+
+static u64 get_clock(void)
+{
+ int ret;
+ u64 clk;
+
+ ret = read(clock_fd, &clk, sizeof(u64));
+ BUG_ON(ret != sizeof(u64));
+
+ return clk;
+}
+
+static void do_read_file(char *filename)
+{
+ int fd;
+ ssize_t size;
+ char buff;
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ return;
+
+ size = read(fd, &buff, sizeof(char));
+ if (size < 0) {
+ close(fd);
+ return;
+ }
+
+ close(fd);
+}
+
+/*
+ * we need to find a mutex lock/unlock sensitive workload, currently
+ * READ operation of both DIR and FILE in sysfs will use mutex lock heavily
+ * each task will read every dir and file under '/sys/module' recursively
+ */
+static void recursive_dir(char *path)
+{
+ struct stat statbuf;
+ struct dirent *dirp;
+ DIR *dp;
+ char *ptr;
+
+ if (lstat(path, &statbuf) < 0) {
+ printf("lstat %s error:%s\n", path, strerror(errno));
+ return;
+ }
+
+ /* not a directory */
+ if (!S_ISDIR(statbuf.st_mode)) {
+ /*
+ * we only read regular file, 3 times to triger mutex lock
+ * as many as possible
+ */
+ if (S_ISREG(statbuf.st_mode)) {
+ do_read_file(path);
+ do_read_file(path);
+ do_read_file(path);
+ }
+ return;
+ }
+
+ ptr = path + strlen(path);
+ *ptr++ = '/';
+ *ptr = 0;
+
+ dp = opendir(path);
+ if (dp == NULL) {
+ printf("opendir %s error:%s\n", path, strerror(errno));
+ return;
+ }
+
+ while ((dirp = readdir(dp)) != NULL) {
+ if (strcmp(dirp->d_name, ".") == 0 ||
+ strcmp(dirp->d_name, "..") == 0)
+ continue;
+ strcpy(ptr, dirp->d_name);
+ recursive_dir(path);
+ }
+
+ if (closedir(dp) < 0)
+ perror("closedir");
+
+}
+
+static inline void do_mutex_bench(MUTEX_BENCH_FN fn, char *dir)
+{
+ BUG_ON(fn == NULL);
+ BUG_ON(dir == NULL);
+ fn(dir);
+}
+
+static void do_bench_func(unsigned int idx)
+{
+ cpu_set_t cpu_set;
+ int cpu;
+ char fullpath[PATH_MAX_LEN];
+ struct timeval tv_start = {0, 0}, tv_end = {0, 0}, tv_diff;
+ u64 clock_start = 0ULL, clock_end = 0ULL;
+
+ CPU_ZERO(&cpu_set);
+ cpu = idx % nr_cpus;
+ CPU_SET(cpu, &cpu_set);
+ BUG_ON(sched_setaffinity(getpid(), sizeof(cpu_set), &cpu_set));
+
+ strcpy(fullpath, TEST_DIR);
+ fullpath[PATH_MAX_LEN - 1] = 0;
+
+ if (use_clock) {
+ clock_start = get_clock();
+ do_mutex_bench(recursive_dir, fullpath);
+ clock_end = get_clock();
+
+ sem_wait(&sdata->sem);
+ sdata->cpu_cycle += clock_end - clock_start;
+ sem_post(&sdata->sem);
+ printf(" [%-6d]/%d cpu clocks %" PRIu64 "\n",
+ getpid(), cpu, clock_end - clock_start);
+
+ } else {
+ BUG_ON(gettimeofday(&tv_start, NULL));
+ do_mutex_bench(recursive_dir, fullpath);
+ BUG_ON(gettimeofday(&tv_end, NULL));
+ timersub(&tv_end, &tv_start, &tv_diff);
+
+ sem_wait(&sdata->sem);
+ timeradd(&sdata->dur, &tv_diff, &sdata->dur);
+ sem_post(&sdata->sem);
+ printf(" [%-6d]/%d duration %8ld s %8ld us\n",
+ getpid(), cpu, tv_diff.tv_sec, tv_diff.tv_usec);
+ }
+}
+
+static void process_time(clock_t real, struct tms *start, struct tms *end)
+{
+ long clktck = 0;
+
+ BUG_ON((clktck = sysconf(_SC_CLK_TCK)) < 0);
+ printf("\n real: %-7.2f s\n", real/(double)clktck);
+ printf(" user: %-7.2f\n",
+ (end->tms_utime - start->tms_utime)/(double)clktck);
+ printf(" sys: %-7.2f\n",
+ (end->tms_stime - start->tms_stime)/(double)clktck);
+}
+
+/*the main entry point of the mutex/semaphore benchmark...*/
+int bench_lock_mutex(int argc, const char **argv,
+ const char *prefix __used)
+{
+ pid_t pid;
+ unsigned int i;
+ void *area;
+ struct tms tms_start, tms_end;
+ clock_t start, end;
+ int status = -1;
+
+ if (argc < 5) {
+ print_usage();
+ goto end;
+ }
+
+ argc = parse_options(argc, argv, options,
+ bench_lock_mutex_usage, 0);
+
+ if (nr_cpus == 0 || nr_tasks > NR_TASK) {
+ printf("Bad options: cpus--[1, ], tasks--[ ,%lu]\n", NR_TASK);
+ goto end;
+ }
+
+ if (use_clock)
+ init_clock();
+
+ area = mmap(0, sizeof(struct mutex_perf_data),
+ PROT_READ | PROT_WRITE,
+ MAP_ANON | MAP_SHARED, -1, 0);
+ if (area == MAP_FAILED) {
+ printf("mmap error:%s\n", strerror(errno));
+ goto end;
+ }
+ sdata = (struct mutex_perf_data *)area;
+
+ if (sem_init(&sdata->sem, 1, 1) == -1) {
+ printf("sem_init error:%s\n", strerror(errno));
+ goto end;
+ }
+
+ signal(SIGCHLD, SIG_IGN);
+
+ BUG_ON((start = times(&tms_start)) == -1);
+ for (i = 0; i < nr_tasks; i++) {
+ pid = fork();
+ if (pid == 0) {
+ do_bench_func(i);
+ return 0;
+ }
+ }
+
+ wait(NULL);
+
+ BUG_ON((end = times(&tms_end)) == -1);
+ printf(" -----------------------------------\n");
+ if (use_clock)
+ printf(" Total cpu cycles %" PRIu64 "\n", sdata->cpu_cycle);
+ else
+ printf(" Total duration %8ld s %8ld us\n",
+ sdata->dur.tv_sec, sdata->dur.tv_usec);
+ process_time(end-start, &tms_start, &tms_end);
+ status = 0;
+end:
+ return status;
+}
--
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