1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *
4  * sched-pipe.c
5  *
6  * pipe: Benchmark for pipe()
7  *
8  * Based on pipe-test-1m.c by Ingo Molnar <mingo@redhat.com>
9  *  http://people.redhat.com/mingo/cfs-scheduler/tools/pipe-test-1m.c
10  * Ported to perf by Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
11  */
12 #include <subcmd/parse-options.h>
13 #include <api/fs/fs.h>
14 #include "bench.h"
15 #include "util/cgroup.h"
16 
17 #include <unistd.h>
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <signal.h>
21 #include <sys/wait.h>
22 #include <string.h>
23 #include <errno.h>
24 #include <fcntl.h>
25 #include <assert.h>
26 #include <sys/epoll.h>
27 #include <sys/time.h>
28 #include <sys/types.h>
29 #include <sys/syscall.h>
30 #include <linux/time64.h>
31 
32 #include <pthread.h>
33 
34 struct thread_data {
35 	int			nr;
36 	int			pipe_read;
37 	int			pipe_write;
38 	struct epoll_event      epoll_ev;
39 	int			epoll_fd;
40 	bool			cgroup_failed;
41 	pthread_t		pthread;
42 };
43 
44 #define LOOPS_DEFAULT 1000000
45 static	int			loops = LOOPS_DEFAULT;
46 
47 /* Use processes by default: */
48 static bool			threaded;
49 
50 static bool			nonblocking;
51 static char			*cgrp_names[2];
52 static struct cgroup		*cgrps[2];
53 
parse_two_cgroups(const struct option * opt __maybe_unused,const char * str,int unset __maybe_unused)54 static int parse_two_cgroups(const struct option *opt __maybe_unused,
55 			     const char *str, int unset __maybe_unused)
56 {
57 	char *p = strdup(str);
58 	char *q;
59 	int ret = -1;
60 
61 	if (p == NULL) {
62 		fprintf(stderr, "memory allocation failure\n");
63 		return -1;
64 	}
65 
66 	q = strchr(p, ',');
67 	if (q == NULL) {
68 		fprintf(stderr, "it should have two cgroup names: %s\n", p);
69 		goto out;
70 	}
71 	*q = '\0';
72 
73 	cgrp_names[0] = strdup(p);
74 	cgrp_names[1] = strdup(q + 1);
75 
76 	if (cgrp_names[0] == NULL || cgrp_names[1] == NULL) {
77 		fprintf(stderr, "memory allocation failure\n");
78 		goto out;
79 	}
80 	ret = 0;
81 
82 out:
83 	free(p);
84 	return ret;
85 }
86 
87 static const struct option options[] = {
88 	OPT_BOOLEAN('n', "nonblocking",	&nonblocking,	"Use non-blocking operations"),
89 	OPT_INTEGER('l', "loop",	&loops,		"Specify number of loops"),
90 	OPT_BOOLEAN('T', "threaded",	&threaded,	"Specify threads/process based task setup"),
91 	OPT_CALLBACK('G', "cgroups", NULL, "SEND,RECV",
92 		     "Put sender and receivers in given cgroups",
93 		     parse_two_cgroups),
94 	OPT_END()
95 };
96 
97 static const char * const bench_sched_pipe_usage[] = {
98 	"perf bench sched pipe <options>",
99 	NULL
100 };
101 
enter_cgroup(int nr)102 static int enter_cgroup(int nr)
103 {
104 	char buf[32];
105 	int fd, len, ret;
106 	int saved_errno;
107 	struct cgroup *cgrp;
108 	pid_t pid;
109 
110 	if (cgrp_names[nr] == NULL)
111 		return 0;
112 
113 	if (cgrps[nr] == NULL) {
114 		cgrps[nr] = cgroup__new(cgrp_names[nr], /*do_open=*/true);
115 		if (cgrps[nr] == NULL)
116 			goto err;
117 	}
118 	cgrp = cgrps[nr];
119 
120 	if (threaded)
121 		pid = syscall(__NR_gettid);
122 	else
123 		pid = getpid();
124 
125 	snprintf(buf, sizeof(buf), "%d\n", pid);
126 	len = strlen(buf);
127 
128 	/* try cgroup v2 interface first */
129 	if (threaded)
130 		fd = openat(cgrp->fd, "cgroup.threads", O_WRONLY);
131 	else
132 		fd = openat(cgrp->fd, "cgroup.procs", O_WRONLY);
133 
134 	/* try cgroup v1 if failed */
135 	if (fd < 0 && errno == ENOENT)
136 		fd = openat(cgrp->fd, "tasks", O_WRONLY);
137 
138 	if (fd < 0)
139 		goto err;
140 
141 	ret = write(fd, buf, len);
142 	close(fd);
143 
144 	if (ret != len) {
145 		printf("Cannot enter to cgroup: %s\n", cgrp->name);
146 		return -1;
147 	}
148 	return 0;
149 
150 err:
151 	saved_errno = errno;
152 	printf("Failed to open cgroup file in %s\n", cgrp_names[nr]);
153 
154 	if (saved_errno == ENOENT) {
155 		char mnt[PATH_MAX];
156 
157 		if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event") == 0)
158 			printf(" Hint: create the cgroup first, like 'mkdir %s/%s'\n",
159 			       mnt, cgrp_names[nr]);
160 	} else if (saved_errno == EACCES && geteuid() > 0) {
161 		printf(" Hint: try to run as root\n");
162 	}
163 
164 	return -1;
165 }
166 
exit_cgroup(int nr)167 static void exit_cgroup(int nr)
168 {
169 	cgroup__put(cgrps[nr]);
170 	free(cgrp_names[nr]);
171 }
172 
read_pipe(struct thread_data * td)173 static inline int read_pipe(struct thread_data *td)
174 {
175 	int ret, m;
176 retry:
177 	if (nonblocking) {
178 		ret = epoll_wait(td->epoll_fd, &td->epoll_ev, 1, -1);
179 		if (ret < 0)
180 			return ret;
181 	}
182 	ret = read(td->pipe_read, &m, sizeof(int));
183 	if (nonblocking && ret < 0 && errno == EWOULDBLOCK)
184 		goto retry;
185 	return ret;
186 }
187 
worker_thread(void * __tdata)188 static void *worker_thread(void *__tdata)
189 {
190 	struct thread_data *td = __tdata;
191 	int i, ret, m = 0;
192 
193 	ret = enter_cgroup(td->nr);
194 	if (ret < 0) {
195 		td->cgroup_failed = true;
196 		return NULL;
197 	}
198 
199 	if (nonblocking) {
200 		td->epoll_ev.events = EPOLLIN;
201 		td->epoll_fd = epoll_create(1);
202 		BUG_ON(td->epoll_fd < 0);
203 		BUG_ON(epoll_ctl(td->epoll_fd, EPOLL_CTL_ADD, td->pipe_read, &td->epoll_ev) < 0);
204 	}
205 
206 	for (i = 0; i < loops; i++) {
207 		ret = write(td->pipe_write, &m, sizeof(int));
208 		BUG_ON(ret != sizeof(int));
209 		ret = read_pipe(td);
210 		BUG_ON(ret != sizeof(int));
211 	}
212 
213 	return NULL;
214 }
215 
bench_sched_pipe(int argc,const char ** argv)216 int bench_sched_pipe(int argc, const char **argv)
217 {
218 	struct thread_data threads[2] = {};
219 	struct thread_data *td;
220 	int pipe_1[2], pipe_2[2];
221 	struct timeval start, stop, diff;
222 	unsigned long long result_usec = 0;
223 	int nr_threads = 2;
224 	int t;
225 
226 	/*
227 	 * why does "ret" exist?
228 	 * discarding returned value of read(), write()
229 	 * causes error in building environment for perf
230 	 */
231 	int __maybe_unused ret, wait_stat, flags = 0;
232 	pid_t pid, retpid __maybe_unused;
233 
234 	argc = parse_options(argc, argv, options, bench_sched_pipe_usage, 0);
235 
236 	if (nonblocking)
237 		flags |= O_NONBLOCK;
238 
239 	BUG_ON(pipe2(pipe_1, flags));
240 	BUG_ON(pipe2(pipe_2, flags));
241 
242 	gettimeofday(&start, NULL);
243 
244 	for (t = 0; t < nr_threads; t++) {
245 		td = threads + t;
246 
247 		td->nr = t;
248 
249 		if (t == 0) {
250 			td->pipe_read = pipe_1[0];
251 			td->pipe_write = pipe_2[1];
252 		} else {
253 			td->pipe_write = pipe_1[1];
254 			td->pipe_read = pipe_2[0];
255 		}
256 	}
257 
258 	if (threaded) {
259 		for (t = 0; t < nr_threads; t++) {
260 			td = threads + t;
261 
262 			ret = pthread_create(&td->pthread, NULL, worker_thread, td);
263 			BUG_ON(ret);
264 		}
265 
266 		for (t = 0; t < nr_threads; t++) {
267 			td = threads + t;
268 
269 			ret = pthread_join(td->pthread, NULL);
270 			BUG_ON(ret);
271 		}
272 	} else {
273 		pid = fork();
274 		assert(pid >= 0);
275 
276 		if (!pid) {
277 			worker_thread(threads + 0);
278 			exit(0);
279 		} else {
280 			worker_thread(threads + 1);
281 		}
282 
283 		retpid = waitpid(pid, &wait_stat, 0);
284 		assert((retpid == pid) && WIFEXITED(wait_stat));
285 	}
286 
287 	gettimeofday(&stop, NULL);
288 	timersub(&stop, &start, &diff);
289 
290 	exit_cgroup(0);
291 	exit_cgroup(1);
292 
293 	if (threads[0].cgroup_failed || threads[1].cgroup_failed)
294 		return 0;
295 
296 	switch (bench_format) {
297 	case BENCH_FORMAT_DEFAULT:
298 		printf("# Executed %d pipe operations between two %s\n\n",
299 			loops, threaded ? "threads" : "processes");
300 
301 		result_usec = diff.tv_sec * USEC_PER_SEC;
302 		result_usec += diff.tv_usec;
303 
304 		printf(" %14s: %lu.%03lu [sec]\n\n", "Total time",
305 		       (unsigned long) diff.tv_sec,
306 		       (unsigned long) (diff.tv_usec / USEC_PER_MSEC));
307 
308 		printf(" %14lf usecs/op\n",
309 		       (double)result_usec / (double)loops);
310 		printf(" %14d ops/sec\n",
311 		       (int)((double)loops /
312 			     ((double)result_usec / (double)USEC_PER_SEC)));
313 		break;
314 
315 	case BENCH_FORMAT_SIMPLE:
316 		printf("%lu.%03lu\n",
317 		       (unsigned long) diff.tv_sec,
318 		       (unsigned long) (diff.tv_usec / USEC_PER_MSEC));
319 		break;
320 
321 	default:
322 		/* reaching here is something disaster */
323 		fprintf(stderr, "Unknown format:%d\n", bench_format);
324 		exit(1);
325 		break;
326 	}
327 
328 	return 0;
329 }
330