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

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of PulseAudio.
   5
   6   Copyright 2004-2006 Lennart Poettering
   7
   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.
  12
  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.
  17
  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
  21   USA.
  22 ***/
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include <config.h>
  26 #endif
  27
  28 #include <pulse/error.h>
  29
  30 #include <pulsecore/core-util.h>
  31 #include <pulsecore/core-error.h>
  32 #include <pulsecore/log.h>
  33
  34 #include "cpulimit.h"
  35
  36 #ifdef HAVE_SIGXCPU
  37
  38 #include <errno.h>
  39 #include <stdio.h>
  40 #include <string.h>
  41 #include <assert.h>
  42 #include <sys/time.h>
  43 #include <unistd.h>
  44 #include <signal.h>
  45
  46 #ifdef HAVE_SYS_RESOURCE_H
  47 #include <sys/resource.h>
  48 #endif
  49
  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. */
  54
  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. */
  61
  62 /* Utilize this much CPU time at maximum */
  63 #define CPUTIME_PERCENT 70
  64
  65 /* Check every 10s */
  66 #define CPUTIME_INTERVAL_SOFT (10)
  67
  68 /* Recheck after 5s */
  69 #define CPUTIME_INTERVAL_HARD (5)
  70
  71 /* Time of the last CPU load check */
  72 static time_t last_time = 0;
  73
  74 /* Pipe for communicating with the main loop */
  75 static int the_pipe[2] = {-1, -1};
  76
  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;
  80
  81 /* Saved sigaction struct for SIGXCPU */
  82 static struct sigaction sigaction_prev;
  83
  84 /* Nonzero after pa_cpu_limit_init() */
  85 static int installed = 0;
  86
  87 /* The current state of operation */
  88 static enum  {
  89     PHASE_IDLE,   /* Normal state */
  90     PHASE_SOFT    /* After CPU overload has been detected */
  91 } phase = PHASE_IDLE;
  92
  93 /* Reset the SIGXCPU timer to the next t seconds */
  94 static void reset_cpu_time(int t) {
  95     int r;
  96     long n;
  97     struct rlimit rl;
  98     struct rusage ru;
  99
 100     /* Get the current CPU time of the current process */
 101     r = getrusage(RUSAGE_SELF, &ru);
 102     assert(r >= 0);
 103
 104     n = ru.ru_utime.tv_sec + ru.ru_stime.tv_sec + t;
 105
 106     r = getrlimit(RLIMIT_CPU, &rl);
 107     assert(r >= 0);
 108
 109     rl.rlim_cur = n;
 110     r = setrlimit(RLIMIT_CPU, &rl);
 111     assert(r >= 0);
 112 }
 113
 114 /* A simple, thread-safe puts() work-alike */
 115 static void write_err(const char *p) {
 116     pa_loop_write(2, p, strlen(p), NULL);
 117 }
 118
 119 /* The signal handler, called on every SIGXCPU */
 120 static void signal_handler(int sig) {
 121     assert(sig == SIGXCPU);
 122
 123     if (phase == PHASE_IDLE) {
 124         time_t now;
 125
 126 #ifdef PRINT_CPU_LOAD
 127         char t[256];
 128 #endif
 129
 130         time(&now);
 131
 132 #ifdef PRINT_CPU_LOAD
 133         snprintf(t, sizeof(t), "Using %0.1f%% CPU\n", (double)CPUTIME_INTERVAL_SOFT/(now-last_time)*100);
 134         write_err(t);
 135 #endif
 136
 137         if (CPUTIME_INTERVAL_SOFT >= ((now-last_time)*(double)CPUTIME_PERCENT/100)) {
 138             static const char c = 'X';
 139
 140             write_err("Soft CPU time limit exhausted, terminating.\n");
 141
 142             /* Try a soft cleanup */
 143             write(the_pipe[1], &c, sizeof(c));
 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         _exit(1); /* Forced exit */
 157     }
 158 }
 159
 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) {
 162     char c;
 163     assert(m && e && f == PA_IO_EVENT_INPUT && e == io_event && fd == the_pipe[0]);
 164     pa_read(the_pipe[0], &c, sizeof(c), NULL);
 165     m->quit(m, 1); /* Quit the main loop */
 166 }
 167
 168 /* Initializes CPU load limiter */
 169 int pa_cpu_limit_init(pa_mainloop_api *m) {
 170     struct sigaction sa;
 171     assert(m && !api && !io_event && the_pipe[0] == -1 && the_pipe[1] == -1 && !installed);
 172
 173     time(&last_time);
 174
 175     /* Prepare the main loop pipe */
 176     if (pipe(the_pipe) < 0) {
 177         pa_log("pipe() failed: %s", pa_cstrerror(errno));
 178         return -1;
 179     }
 180
 181     pa_make_nonblock_fd(the_pipe[0]);
 182     pa_make_nonblock_fd(the_pipe[1]);
 183     pa_fd_set_cloexec(the_pipe[0], 1);
 184     pa_fd_set_cloexec(the_pipe[1], 1);
 185
 186     api = m;
 187     io_event = api->io_new(m, the_pipe[0], PA_IO_EVENT_INPUT, callback, NULL);
 188
 189     phase = PHASE_IDLE;
 190
 191     /* Install signal handler for SIGXCPU */
 192     memset(&sa, 0, sizeof(sa));
 193     sa.sa_handler = signal_handler;
 194     sigemptyset(&sa.sa_mask);
 195     sa.sa_flags = SA_RESTART;
 196
 197     if (sigaction(SIGXCPU, &sa, &sigaction_prev) < 0) {
 198         pa_cpu_limit_done();
 199         return -1;
 200     }
 201
 202     installed = 1;
 203
 204     reset_cpu_time(CPUTIME_INTERVAL_SOFT);
 205
 206     return 0;
 207 }
 208
 209 /* Shutdown CPU load limiter */
 210 void pa_cpu_limit_done(void) {
 211     int r;
 212
 213     if (io_event) {
 214         assert(api);
 215         api->io_free(io_event);
 216         io_event = NULL;
 217         api = NULL;
 218     }
 219
 220     if (the_pipe[0] >= 0)
 221         close(the_pipe[0]);
 222     if (the_pipe[1] >= 0)
 223         close(the_pipe[1]);
 224     the_pipe[0] = the_pipe[1] = -1;
 225
 226     if (installed) {
 227         r = sigaction(SIGXCPU, &sigaction_prev, NULL);
 228         assert(r >= 0);
 229         installed = 0;
 230     }
 231 }
 232
 233 #else /* HAVE_SIGXCPU */
 234
 235 int pa_cpu_limit_init(PA_GCC_UNUSED pa_mainloop_api *m) {
 236     return 0;
 237 }
 238
 239 void pa_cpu_limit_done(void) {
 240 }
 241
 242 #endif