2 This file is part of PulseAudio.
4 Copyright 2004-2006 Lennart Poettering
6 PulseAudio is free software; you can redistribute it and/or modify
7 it under the terms of the GNU Lesser General Public License as
8 published by the Free Software Foundation; either version 2.1 of the
9 License, or (at your option) any later version.
11 PulseAudio is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with PulseAudio; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
26 #include <pulse/error.h>
27 #include <pulse/rtclock.h>
28 #include <pulse/timeval.h>
30 #include <pulsecore/core-rtclock.h>
31 #include <pulsecore/core-util.h>
32 #include <pulsecore/core-error.h>
33 #include <pulsecore/log.h>
34 #include <pulsecore/macro.h>
47 #ifdef HAVE_SYS_RESOURCE_H
48 #include <sys/resource.h>
51 /* This module implements a watchdog that makes sure that the current
52 * process doesn't consume more than 70% CPU time for 10 seconds. This
53 * is very useful when using SCHED_FIFO scheduling which effectively
54 * disables multitasking. */
56 /* Method of operation: Using SIGXCPU a signal handler is called every
57 * 10s process CPU time. That function checks if less than 14s system
58 * time have passed. In that case, it tries to contact the main event
59 * loop through a pipe. After two additional seconds it is checked
60 * whether the main event loop contact was successful. If not, the
61 * program is terminated forcibly. */
63 /* Utilize this much CPU time at maximum */
64 #define CPUTIME_PERCENT 70
67 #define CPUTIME_INTERVAL_SOFT (10)
69 /* Recheck after 5s */
70 #define CPUTIME_INTERVAL_HARD (5)
72 /* Time of the last CPU load check */
73 static pa_usec_t last_time = 0;
75 /* Pipe for communicating with the main loop */
76 static int the_pipe[2] = {-1, -1};
78 /* Main event loop and IO event for the FIFO */
79 static pa_mainloop_api *api = NULL;
80 static pa_io_event *io_event = NULL;
82 /* Saved sigaction struct for SIGXCPU */
83 static struct sigaction sigaction_prev;
85 /* Nonzero after pa_cpu_limit_init() */
86 static pa_bool_t installed = FALSE;
88 /* The current state of operation */
90 PHASE_IDLE, /* Normal state */
91 PHASE_SOFT /* After CPU overload has been detected */
94 /* Reset the SIGXCPU timer to the next t seconds */
95 static void reset_cpu_time(int t) {
100 /* Get the current CPU time of the current process */
101 pa_assert_se(getrusage(RUSAGE_SELF, &ru) >= 0);
103 n = ru.ru_utime.tv_sec + ru.ru_stime.tv_sec + t;
104 pa_assert_se(getrlimit(RLIMIT_CPU, &rl) >= 0);
106 rl.rlim_cur = (rlim_t) n;
107 pa_assert_se(setrlimit(RLIMIT_CPU, &rl) >= 0);
110 /* A simple, thread-safe puts() work-alike */
111 static void write_err(const char *p) {
112 pa_loop_write(2, p, strlen(p), NULL);
115 /* The signal handler, called on every SIGXCPU */
116 static void signal_handler(int sig) {
120 pa_assert(sig == SIGXCPU);
122 if (phase == PHASE_IDLE) {
123 pa_usec_t now, elapsed;
125 #ifdef PRINT_CPU_LOAD
129 now = pa_rtclock_now();
130 elapsed = now - last_time;
132 #ifdef PRINT_CPU_LOAD
133 pa_snprintf(t, sizeof(t), "Using %0.1f%% CPU\n", ((double) CPUTIME_INTERVAL_SOFT * (double) PA_USEC_PER_SEC) / (double) elapsed * 100.0);
137 if (((double) CPUTIME_INTERVAL_SOFT * (double) PA_USEC_PER_SEC) >= ((double) elapsed * (double) CPUTIME_PERCENT / 100.0)) {
138 static const char c = 'X';
140 write_err("Soft CPU time limit exhausted, terminating.\n");
142 /* Try a soft cleanup */
143 (void) pa_write(the_pipe[1], &c, sizeof(c), NULL);
145 reset_cpu_time(CPUTIME_INTERVAL_HARD);
149 /* Everything's fine */
150 reset_cpu_time(CPUTIME_INTERVAL_SOFT);
154 } else if (phase == PHASE_SOFT) {
155 write_err("Hard CPU time limit exhausted, terminating forcibly.\n");
156 abort(); /* Forced exit */
162 /* Callback for IO events on the FIFO */
163 static void callback(pa_mainloop_api*m, pa_io_event*e, int fd, pa_io_event_flags_t f, void *userdata) {
167 pa_assert(f == PA_IO_EVENT_INPUT);
168 pa_assert(e == io_event);
169 pa_assert(fd == the_pipe[0]);
171 pa_log("Received request to terminate due to CPU overload.");
173 pa_read(the_pipe[0], &c, sizeof(c), NULL);
174 m->quit(m, 1); /* Quit the main loop */
177 /* Initializes CPU load limiter */
178 int pa_cpu_limit_init(pa_mainloop_api *m) {
183 pa_assert(!io_event);
184 pa_assert(the_pipe[0] == -1);
185 pa_assert(the_pipe[1] == -1);
186 pa_assert(!installed);
188 last_time = pa_rtclock_now();
190 /* Prepare the main loop pipe */
191 if (pa_pipe_cloexec(the_pipe) < 0) {
192 pa_log("pipe() failed: %s", pa_cstrerror(errno));
196 pa_make_fd_nonblock(the_pipe[0]);
197 pa_make_fd_nonblock(the_pipe[1]);
200 io_event = api->io_new(m, the_pipe[0], PA_IO_EVENT_INPUT, callback, NULL);
204 /* Install signal handler for SIGXCPU */
205 memset(&sa, 0, sizeof(sa));
206 sa.sa_handler = signal_handler;
207 sigemptyset(&sa.sa_mask);
208 sa.sa_flags = SA_RESTART;
210 if (sigaction(SIGXCPU, &sa, &sigaction_prev) < 0) {
217 reset_cpu_time(CPUTIME_INTERVAL_SOFT);
222 /* Shutdown CPU load limiter */
223 void pa_cpu_limit_done(void) {
227 api->io_free(io_event);
232 pa_close_pipe(the_pipe);
235 pa_assert_se(sigaction(SIGXCPU, &sigaction_prev, NULL) >= 0);
240 #else /* HAVE_SIGXCPU */
242 int pa_cpu_limit_init(pa_mainloop_api *m) {
246 void pa_cpu_limit_done(void) {