1 // SPDX-License-Identifier: GPL-2.0
11  *                          |---> [worker A]
12  *                          |---> [worker B]
13  *        [combined queue]  .---> [worker C]
14  *                          |---> [worker D]
15  *                          |---> [worker E]
17  * While the second model, enabled via --multiq option, uses multiple
23  *             [queue A]  ---> [worker]
24  *             [queue B]  ---> [worker]
25  *             [queue C]  ---> [worker]
26  *             [queue D]  ---> [worker]
27  *             [queue E]  ---> [worker]
37  * epoll_wait not finding any ready read events and blocking as this
40  * epoll_wait(2) blocking as the lineal writer thread will take "longer",
44  * not stress scenarios where multiple tasks are awoken per ready IO; ie:
52  *        ... where [others] is the cost of re-adding the fd (EPOLLET),
58  * IO polling methods, for example. Hence everything is very adhoc and
83 #include <subcmd/parse-options.h>
106 static bool et; /* edge-trigger */
120 	int epollfd; /* for --multiq */
140 	OPT_BOOLEAN( 'E', "edge",  &et,   "Use Edge-triggered interface (default is LT)"),
155  * number generator. -- Ben Pfaff.
171 		size_t j =   i + rand() / (RAND_MAX / (n - i) + 1);  in shuffle()
187 	unsigned long ops = w->ops;  in workerfn()
190 	int to = nonblocking? 0 : -1;  in workerfn()
191 	int efd = multiq ? w->epollfd : epollfd;  in workerfn()
194 	threads_starting--;  in workerfn()
234 		close(w->epollfd);  in workerfn()
236 	w->ops = ops;  in workerfn()
244 	int efd = multiq ? w->epollfd : epollfd;  in nest_epollfd()
262 	for (i = nested - 1; i; i--) {  in nest_epollfd()
263 		if (epoll_ctl(epollfdp[i - 1], EPOLL_CTL_ADD,  in nest_epollfd()
287 	printf("\nAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",  in print_summary()
314 			w->epollfd = epoll_create(1);  in do_threads()
315 			if (w->epollfd < 0)  in do_threads()
322 		w->tid = i;  in do_threads()
323 		w->fdmap = calloc(nfds, sizeof(int));  in do_threads()
324 		if (!w->fdmap)  in do_threads()
328 			int efd = multiq ? w->epollfd : epollfd;  in do_threads()
331 			w->fdmap[j] = eventfd(0, EFD_NONBLOCK);  in do_threads()
332 			if (w->fdmap[j] < 0)  in do_threads()
335 			ev.data.fd = w->fdmap[j];  in do_threads()
339 					w->fdmap[j], &ev);  in do_threads()
346 			CPU_SET(cpu->map[i % cpu->nr], &cpuset);  in do_threads()
355 		ret = pthread_create(&w->thread, attrp, workerfn,  in do_threads()
376 	printinfo("starting writer-thread: doing %s writes ...\n",  in writerfn()
388 				shuffle((void *)w->fdmap, nfds, sizeof(int));  in writerfn()
393 					sz = write(w->fdmap[j], &val, sizeof(val));  in writerfn()
401 	printinfo("exiting writer-thread (total full-loops: %zd)\n", iter);  in writerfn()
410 	return w1->tid > w2->tid;  in cmpworker()
456 		nthreads = cpu->nr - 1;  in bench_epoll_wait()
472 	       "%d file-descriptors for %d secs.\n\n",  in bench_epoll_wait()
533 			       &worker[i].fdmap[nfds-1], t);  in bench_epoll_wait()