code.delx.au - pulseaudio/blob - src/daemon/cpulimit.c

   1 /***
   2   This file is part of PulseAudio.
   3
   4   Copyright 2004-2006 Lennart Poettering
   5
   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.
  10
  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.
  15
  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
  19   USA.
  20 ***/
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <pulse/error.h>
  27 #include <pulse/rtclock.h>
  28 #include <pulse/timeval.h>
  29
  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>
  35
  36 #include "cpulimit.h"
  37
  38 #ifdef HAVE_SIGXCPU
  39
  40 #include <errno.h>
  41 #include <stdio.h>
  42 #include <string.h>
  43 #include <sys/time.h>
  44 #include <unistd.h>
  45 #include <signal.h>
  46
  47 #ifdef HAVE_SYS_RESOURCE_H
  48 #include <sys/resource.h>
  49 #endif
  50
  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. */
  55
  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. */
  62
  63 /* Utilize this much CPU time at maximum */
  64 #define CPUTIME_PERCENT 70
  65
  66 /* Check every 10s */
  67 #define CPUTIME_INTERVAL_SOFT (10)
  68
  69 /* Recheck after 5s */
  70 #define CPUTIME_INTERVAL_HARD (5)
  71
  72 /* Time of the last CPU load check */
  73 static pa_usec_t last_time = 0;
  74
  75 /* Pipe for communicating with the main loop */
  76 static int the_pipe[2] = {-1, -1};
  77
  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;
  81
  82 /* Saved sigaction struct for SIGXCPU */
  83 static struct sigaction sigaction_prev;
  84
  85 /* Nonzero after pa_cpu_limit_init() */
  86 static pa_bool_t installed = FALSE;
  87
  88 /* The current state of operation */
  89 static enum {
  90     PHASE_IDLE,   /* Normal state */
  91     PHASE_SOFT    /* After CPU overload has been detected */
  92 } phase = PHASE_IDLE;
  93
  94 /* Reset the SIGXCPU timer to the next t seconds */
  95 static void reset_cpu_time(int t) {
  96     long n;
  97     struct rlimit rl;
  98     struct rusage ru;
  99
 100     /* Get the current CPU time of the current process */
 101     pa_assert_se(getrusage(RUSAGE_SELF, &ru) >= 0);
 102
 103     n = ru.ru_utime.tv_sec + ru.ru_stime.tv_sec + t;
 104     pa_assert_se(getrlimit(RLIMIT_CPU, &rl) >= 0);
 105
 106     rl.rlim_cur = (rlim_t) n;
 107     pa_assert_se(setrlimit(RLIMIT_CPU, &rl) >= 0);
 108 }
 109
 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);
 113 }
 114
 115 /* The signal handler, called on every SIGXCPU */
 116 static void signal_handler(int sig) {
 117     int saved_errno;
 118
 119     saved_errno = errno;
 120     pa_assert(sig == SIGXCPU);
 121
 122     if (phase == PHASE_IDLE) {
 123         pa_usec_t now, elapsed;
 124
 125 #ifdef PRINT_CPU_LOAD
 126         char t[256];
 127 #endif
 128
 129         now = pa_rtclock_now();
 130         elapsed = now - last_time;
 131
 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);
 134         write_err(t);
 135 #endif
 136
 137         if (((double) CPUTIME_INTERVAL_SOFT * (double) PA_USEC_PER_SEC) >= ((double) elapsed * (double) CPUTIME_PERCENT / 100.0)) {
 138             static const char c = 'X';
 139
 140             write_err("Soft CPU time limit exhausted, terminating.\n");
 141
 142             /* Try a soft cleanup */
 143             (void) pa_write(the_pipe[1], &c, sizeof(c), NULL);
 144             phase = PHASE_SOFT;
 145             reset_cpu_time(CPUTIME_INTERVAL_HARD);
 146
 147         } else {
 148
 149             /* Everything's fine */
 150             reset_cpu_time(CPUTIME_INTERVAL_SOFT);
 151             last_time = now;
 152         }
 153
 154     } else if (phase == PHASE_SOFT) {
 155         write_err("Hard CPU time limit exhausted, terminating forcibly.\n");
 156         abort(); /* Forced exit */
 157     }
 158
 159     errno = saved_errno;
 160 }
 161
 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) {
 164     char c;
 165     pa_assert(m);
 166     pa_assert(e);
 167     pa_assert(f == PA_IO_EVENT_INPUT);
 168     pa_assert(e == io_event);
 169     pa_assert(fd == the_pipe[0]);
 170
 171     pa_log("Received request to terminate due to CPU overload.");
 172
 173     pa_read(the_pipe[0], &c, sizeof(c), NULL);
 174     m->quit(m, 1); /* Quit the main loop */
 175 }
 176
 177 /* Initializes CPU load limiter */
 178 int pa_cpu_limit_init(pa_mainloop_api *m) {
 179     struct sigaction sa;
 180
 181     pa_assert(m);
 182     pa_assert(!api);
 183     pa_assert(!io_event);
 184     pa_assert(the_pipe[0] == -1);
 185     pa_assert(the_pipe[1] == -1);
 186     pa_assert(!installed);
 187
 188     last_time = pa_rtclock_now();
 189
 190     /* Prepare the main loop pipe */
 191     if (pa_pipe_cloexec(the_pipe) < 0) {
 192         pa_log("pipe() failed: %s", pa_cstrerror(errno));
 193         return -1;
 194     }
 195
 196     pa_make_fd_nonblock(the_pipe[0]);
 197     pa_make_fd_nonblock(the_pipe[1]);
 198
 199     api = m;
 200     io_event = api->io_new(m, the_pipe[0], PA_IO_EVENT_INPUT, callback, NULL);
 201
 202     phase = PHASE_IDLE;
 203
 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;
 209
 210     if (sigaction(SIGXCPU, &sa, &sigaction_prev) < 0) {
 211         pa_cpu_limit_done();
 212         return -1;
 213     }
 214
 215     installed = TRUE;
 216
 217     reset_cpu_time(CPUTIME_INTERVAL_SOFT);
 218
 219     return 0;
 220 }
 221
 222 /* Shutdown CPU load limiter */
 223 void pa_cpu_limit_done(void) {
 224
 225     if (io_event) {
 226         pa_assert(api);
 227         api->io_free(io_event);
 228         io_event = NULL;
 229         api = NULL;
 230     }
 231
 232     pa_close_pipe(the_pipe);
 233
 234     if (installed) {
 235         pa_assert_se(sigaction(SIGXCPU, &sigaction_prev, NULL) >= 0);
 236         installed = FALSE;
 237     }
 238 }
 239
 240 #else /* HAVE_SIGXCPU */
 241
 242 int pa_cpu_limit_init(pa_mainloop_api *m) {
 243     return 0;
 244 }
 245
 246 void pa_cpu_limit_done(void) {
 247 }
 248
 249 #endif