4 This file is part of PulseAudio.
6 Copyright 2004-2006 Lennart Poettering
8 PulseAudio is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Lesser General Public License as
10 published by the Free Software Foundation; either version 2 of the
11 License, or (at your option) any later version.
13 PulseAudio is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public
19 License along with PulseAudio; if not, write to the Free Software
20 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
28 #include <pulse/error.h>
30 #include <pulsecore/core-util.h>
31 #include <pulsecore/core-error.h>
32 #include <pulsecore/log.h>
33 #include <pulsecore/macro.h>
46 #ifdef HAVE_SYS_RESOURCE_H
47 #include <sys/resource.h>
50 /* This module implements a watchdog that makes sure that the current
51 * process doesn't consume more than 70% CPU time for 10 seconds. This
52 * is very useful when using SCHED_FIFO scheduling which effectively
53 * disables multitasking. */
55 /* Method of operation: Using SIGXCPU a signal handler is called every
56 * 10s process CPU time. That function checks if less than 14s system
57 * time have passed. In that case, it tries to contact the main event
58 * loop through a pipe. After two additional seconds it is checked
59 * whether the main event loop contact was successful. If not, the
60 * program is terminated forcibly. */
62 /* Utilize this much CPU time at maximum */
63 #define CPUTIME_PERCENT 70
66 #define CPUTIME_INTERVAL_SOFT (10)
68 /* Recheck after 5s */
69 #define CPUTIME_INTERVAL_HARD (5)
71 /* Time of the last CPU load check */
72 static time_t last_time
= 0;
74 /* Pipe for communicating with the main loop */
75 static int the_pipe
[2] = {-1, -1};
77 /* Main event loop and IO event for the FIFO */
78 static pa_mainloop_api
*api
= NULL
;
79 static pa_io_event
*io_event
= NULL
;
81 /* Saved sigaction struct for SIGXCPU */
82 static struct sigaction sigaction_prev
;
84 /* Nonzero after pa_cpu_limit_init() */
85 static int installed
= 0;
87 /* The current state of operation */
89 PHASE_IDLE
, /* Normal state */
90 PHASE_SOFT
/* After CPU overload has been detected */
93 /* Reset the SIGXCPU timer to the next t seconds */
94 static void reset_cpu_time(int t
) {
99 /* Get the current CPU time of the current process */
100 pa_assert_se(getrusage(RUSAGE_SELF
, &ru
) >= 0);
102 n
= ru
.ru_utime
.tv_sec
+ ru
.ru_stime
.tv_sec
+ t
;
103 pa_assert_se(getrlimit(RLIMIT_CPU
, &rl
) >= 0);
106 pa_assert_se(setrlimit(RLIMIT_CPU
, &rl
) >= 0);
109 /* A simple, thread-safe puts() work-alike */
110 static void write_err(const char *p
) {
111 pa_loop_write(2, p
, strlen(p
), NULL
);
114 /* The signal handler, called on every SIGXCPU */
115 static void signal_handler(int sig
) {
119 pa_assert(sig
== SIGXCPU
);
121 if (phase
== PHASE_IDLE
) {
124 #ifdef PRINT_CPU_LOAD
130 #ifdef PRINT_CPU_LOAD
131 pa_snprintf(t
, sizeof(t
), "Using %0.1f%% CPU\n", (double)CPUTIME_INTERVAL_SOFT
/(now
-last_time
)*100);
135 if (CPUTIME_INTERVAL_SOFT
>= ((now
-last_time
)*(double)CPUTIME_PERCENT
/100)) {
136 static const char c
= 'X';
138 write_err("Soft CPU time limit exhausted, terminating.\n");
140 /* Try a soft cleanup */
141 write(the_pipe
[1], &c
, sizeof(c
));
143 reset_cpu_time(CPUTIME_INTERVAL_HARD
);
147 /* Everything's fine */
148 reset_cpu_time(CPUTIME_INTERVAL_SOFT
);
152 } else if (phase
== PHASE_SOFT
) {
153 write_err("Hard CPU time limit exhausted, terminating forcibly.\n");
154 _exit(1); /* Forced exit */
160 /* Callback for IO events on the FIFO */
161 static void callback(pa_mainloop_api
*m
, pa_io_event
*e
, int fd
, pa_io_event_flags_t f
, void *userdata
) {
165 pa_assert(f
== PA_IO_EVENT_INPUT
);
166 pa_assert(e
== io_event
);
167 pa_assert(fd
== the_pipe
[0]);
169 pa_read(the_pipe
[0], &c
, sizeof(c
), NULL
);
170 m
->quit(m
, 1); /* Quit the main loop */
173 /* Initializes CPU load limiter */
174 int pa_cpu_limit_init(pa_mainloop_api
*m
) {
179 pa_assert(!io_event
);
180 pa_assert(the_pipe
[0] == -1);
181 pa_assert(the_pipe
[1] == -1);
182 pa_assert(!installed
);
186 /* Prepare the main loop pipe */
187 if (pipe(the_pipe
) < 0) {
188 pa_log("pipe() failed: %s", pa_cstrerror(errno
));
192 pa_make_fd_nonblock(the_pipe
[0]);
193 pa_make_fd_nonblock(the_pipe
[1]);
194 pa_make_fd_cloexec(the_pipe
[0]);
195 pa_make_fd_cloexec(the_pipe
[1]);
198 io_event
= api
->io_new(m
, the_pipe
[0], PA_IO_EVENT_INPUT
, callback
, NULL
);
202 /* Install signal handler for SIGXCPU */
203 memset(&sa
, 0, sizeof(sa
));
204 sa
.sa_handler
= signal_handler
;
205 sigemptyset(&sa
.sa_mask
);
206 sa
.sa_flags
= SA_RESTART
;
208 if (sigaction(SIGXCPU
, &sa
, &sigaction_prev
) < 0) {
215 reset_cpu_time(CPUTIME_INTERVAL_SOFT
);
220 /* Shutdown CPU load limiter */
221 void pa_cpu_limit_done(void) {
225 api
->io_free(io_event
);
230 pa_close_pipe(the_pipe
);
233 pa_assert_se(sigaction(SIGXCPU
, &sigaction_prev
, NULL
) >= 0);
238 #else /* HAVE_SIGXCPU */
240 int pa_cpu_limit_init(PA_GCC_UNUSED pa_mainloop_api
*m
) {
244 void pa_cpu_limit_done(void) {