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 #include <pulsecore/macro.h>
  34
  35 #include "cpulimit.h"
  36
  37 #ifdef HAVE_SIGXCPU
  38
  39 #include <errno.h>
  40 #include <stdio.h>
  41 #include <string.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     long n;
  96     struct rlimit rl;
  97     struct rusage ru;
  98
  99     /* Get the current CPU time of the current process */
 100     pa_assert_se(getrusage(RUSAGE_SELF, &ru) >= 0);
 101
 102     n = ru.ru_utime.tv_sec + ru.ru_stime.tv_sec + t;
 103     pa_assert_se(getrlimit(RLIMIT_CPU, &rl) >= 0);
 104
 105     rl.rlim_cur = n;
 106     pa_assert_se(setrlimit(RLIMIT_CPU, &rl) >= 0);
 107 }
 108
 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);
 112 }
 113
 114 /* The signal handler, called on every SIGXCPU */
 115 static void signal_handler(int sig) {
 116     int saved_errno;
 117
 118     saved_errno = errno;
 119     pa_assert(sig == SIGXCPU);
 120
 121     if (phase == PHASE_IDLE) {
 122         time_t now;
 123
 124 #ifdef PRINT_CPU_LOAD
 125         char t[256];
 126 #endif
 127
 128         time(&now);
 129
 130 #ifdef PRINT_CPU_LOAD
 131         pa_snprintf(t, sizeof(t), "Using %0.1f%% CPU\n", (double)CPUTIME_INTERVAL_SOFT/(now-last_time)*100);
 132         write_err(t);
 133 #endif
 134
 135         if (CPUTIME_INTERVAL_SOFT >= ((now-last_time)*(double)CPUTIME_PERCENT/100)) {
 136             static const char c = 'X';
 137
 138             write_err("Soft CPU time limit exhausted, terminating.\n");
 139
 140             /* Try a soft cleanup */
 141             write(the_pipe[1], &c, sizeof(c));
 142             phase = PHASE_SOFT;
 143             reset_cpu_time(CPUTIME_INTERVAL_HARD);
 144
 145         } else {
 146
 147             /* Everything's fine */
 148             reset_cpu_time(CPUTIME_INTERVAL_SOFT);
 149             last_time = now;
 150         }
 151
 152     } else if (phase == PHASE_SOFT) {
 153         write_err("Hard CPU time limit exhausted, terminating forcibly.\n");
 154         _exit(1); /* Forced exit */
 155     }
 156
 157     errno = saved_errno;
 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     pa_assert(m);
 164     pa_assert(e);
 165     pa_assert(f == PA_IO_EVENT_INPUT);
 166     pa_assert(e == io_event);
 167     pa_assert(fd == the_pipe[0]);
 168
 169     pa_read(the_pipe[0], &c, sizeof(c), NULL);
 170     m->quit(m, 1); /* Quit the main loop */
 171 }
 172
 173 /* Initializes CPU load limiter */
 174 int pa_cpu_limit_init(pa_mainloop_api *m) {
 175     struct sigaction sa;
 176
 177     pa_assert(m);
 178     pa_assert(!api);
 179     pa_assert(!io_event);
 180     pa_assert(the_pipe[0] == -1);
 181     pa_assert(the_pipe[1] == -1);
 182     pa_assert(!installed);
 183
 184     time(&last_time);
 185
 186     /* Prepare the main loop pipe */
 187     if (pipe(the_pipe) < 0) {
 188         pa_log("pipe() failed: %s", pa_cstrerror(errno));
 189         return -1;
 190     }
 191
 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]);
 196
 197     api = m;
 198     io_event = api->io_new(m, the_pipe[0], PA_IO_EVENT_INPUT, callback, NULL);
 199
 200     phase = PHASE_IDLE;
 201
 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;
 207
 208     if (sigaction(SIGXCPU, &sa, &sigaction_prev) < 0) {
 209         pa_cpu_limit_done();
 210         return -1;
 211     }
 212
 213     installed = 1;
 214
 215     reset_cpu_time(CPUTIME_INTERVAL_SOFT);
 216
 217     return 0;
 218 }
 219
 220 /* Shutdown CPU load limiter */
 221 void pa_cpu_limit_done(void) {
 222
 223     if (io_event) {
 224         pa_assert(api);
 225         api->io_free(io_event);
 226         io_event = NULL;
 227         api = NULL;
 228     }
 229
 230     pa_close_pipe(the_pipe);
 231
 232     if (installed) {
 233         pa_assert_se(sigaction(SIGXCPU, &sigaction_prev, NULL) >= 0);
 234         installed = 0;
 235     }
 236 }
 237
 238 #else /* HAVE_SIGXCPU */
 239
 240 int pa_cpu_limit_init(PA_GCC_UNUSED pa_mainloop_api *m) {
 241     return 0;
 242 }
 243
 244 void pa_cpu_limit_done(void) {
 245 }
 246
 247 #endif