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 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/timeval.h>
  28
  29 #include <pulsecore/core-util.h>
  30 #include <pulsecore/core-error.h>
  31 #include <pulsecore/log.h>
  32 #include <pulsecore/macro.h>
  33 #include <pulsecore/rtclock.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 pa_usec_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 pa_bool_t installed = FALSE;
  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 = (rlim_t) 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         pa_usec_t now, elapsed;
 123
 124 #ifdef PRINT_CPU_LOAD
 125         char t[256];
 126 #endif
 127
 128         now = pa_rtclock_usec();
 129         elapsed = now - last_time;
 130
 131 #ifdef PRINT_CPU_LOAD
 132         pa_snprintf(t, sizeof(t), "Using %0.1f%% CPU\n", ((double) CPUTIME_INTERVAL_SOFT * (double) PA_USEC_PER_SEC) / (double) elapsed * 100.0);
 133         write_err(t);
 134 #endif
 135
 136         if (((double) CPUTIME_INTERVAL_SOFT * (double) PA_USEC_PER_SEC) >= ((double) elapsed * (double) CPUTIME_PERCENT / 100.0)) {
 137             static const char c = 'X';
 138
 139             write_err("Soft CPU time limit exhausted, terminating.\n");
 140
 141             /* Try a soft cleanup */
 142             write(the_pipe[1], &c, sizeof(c));
 143             phase = PHASE_SOFT;
 144             reset_cpu_time(CPUTIME_INTERVAL_HARD);
 145
 146         } else {
 147
 148             /* Everything's fine */
 149             reset_cpu_time(CPUTIME_INTERVAL_SOFT);
 150             last_time = now;
 151         }
 152
 153     } else if (phase == PHASE_SOFT) {
 154         write_err("Hard CPU time limit exhausted, terminating forcibly.\n");
 155         abort(); /* Forced exit */
 156     }
 157
 158     errno = saved_errno;
 159 }
 160
 161 /* Callback for IO events on the FIFO */
 162 static void callback(pa_mainloop_api*m, pa_io_event*e, int fd, pa_io_event_flags_t f, void *userdata) {
 163     char c;
 164     pa_assert(m);
 165     pa_assert(e);
 166     pa_assert(f == PA_IO_EVENT_INPUT);
 167     pa_assert(e == io_event);
 168     pa_assert(fd == the_pipe[0]);
 169
 170     pa_log("Recevied request to terminate due to CPU overload.");
 171
 172     pa_read(the_pipe[0], &c, sizeof(c), NULL);
 173     m->quit(m, 1); /* Quit the main loop */
 174 }
 175
 176 /* Initializes CPU load limiter */
 177 int pa_cpu_limit_init(pa_mainloop_api *m) {
 178     struct sigaction sa;
 179
 180     pa_assert(m);
 181     pa_assert(!api);
 182     pa_assert(!io_event);
 183     pa_assert(the_pipe[0] == -1);
 184     pa_assert(the_pipe[1] == -1);
 185     pa_assert(!installed);
 186
 187     last_time = pa_rtclock_usec();
 188
 189     /* Prepare the main loop pipe */
 190     if (pipe(the_pipe) < 0) {
 191         pa_log("pipe() failed: %s", pa_cstrerror(errno));
 192         return -1;
 193     }
 194
 195     pa_make_fd_nonblock(the_pipe[0]);
 196     pa_make_fd_nonblock(the_pipe[1]);
 197     pa_make_fd_cloexec(the_pipe[0]);
 198     pa_make_fd_cloexec(the_pipe[1]);
 199
 200     api = m;
 201     io_event = api->io_new(m, the_pipe[0], PA_IO_EVENT_INPUT, callback, NULL);
 202
 203     phase = PHASE_IDLE;
 204
 205     /* Install signal handler for SIGXCPU */
 206     memset(&sa, 0, sizeof(sa));
 207     sa.sa_handler = signal_handler;
 208     sigemptyset(&sa.sa_mask);
 209     sa.sa_flags = SA_RESTART;
 210
 211     if (sigaction(SIGXCPU, &sa, &sigaction_prev) < 0) {
 212         pa_cpu_limit_done();
 213         return -1;
 214     }
 215
 216     installed = TRUE;
 217
 218     reset_cpu_time(CPUTIME_INTERVAL_SOFT);
 219
 220     return 0;
 221 }
 222
 223 /* Shutdown CPU load limiter */
 224 void pa_cpu_limit_done(void) {
 225
 226     if (io_event) {
 227         pa_assert(api);
 228         api->io_free(io_event);
 229         io_event = NULL;
 230         api = NULL;
 231     }
 232
 233     pa_close_pipe(the_pipe);
 234
 235     if (installed) {
 236         pa_assert_se(sigaction(SIGXCPU, &sigaction_prev, NULL) >= 0);
 237         installed = FALSE;
 238     }
 239 }
 240
 241 #else /* HAVE_SIGXCPU */
 242
 243 int pa_cpu_limit_init(pa_mainloop_api *m) {
 244     return 0;
 245 }
 246
 247 void pa_cpu_limit_done(void) {
 248 }
 249
 250 #endif