1 /* -----------------------------------------------------------------------------
2 * $Id: Itimer.c,v 1.21 2001/02/27 12:43:45 rrt Exp $
4 * (c) The GHC Team, 1995-1999
6 * Interval timer for profiling and pre-emptive scheduling.
8 * ---------------------------------------------------------------------------*/
11 * The interval timer is used for profiling and for context switching in the
12 * threaded build. Though POSIX 1003.1b includes a standard interface for
13 * such things, no one really seems to be implementing them yet. Even
14 * Solaris 2.3 only seems to provide support for @CLOCK_REAL@, whereas we're
15 * keen on getting access to @CLOCK_VIRTUAL@.
17 * Hence, we use the old-fashioned @setitimer@ that just about everyone seems
18 * to support. So much for standards.
22 # define NON_POSIX_SOURCE
28 #include "Proftimer.h"
31 /* As recommended in the autoconf manual */
32 # ifdef TIME_WITH_SYS_TIME
33 # include <sys/time.h>
36 # ifdef HAVE_SYS_TIME_H
37 # include <sys/time.h>
49 /* ticks left before next pre-emptive context switch */
50 int ticks_to_ctxt_switch = 0;
52 /* -----------------------------------------------------------------------------
55 We use the ticker for time profiling.
57 SMP note: this signal could be delivered to *any* thread. We have
58 to ensure that it doesn't matter which thread actually runs the
60 -------------------------------------------------------------------------- */
64 #if defined(mingw32_TARGET_OS) || (defined(cygwin32_TARGET_OS) && !defined(HAVE_SETITIMER))
66 handle_tick(UINT uID STG_UNUSED, UINT uMsg STG_UNUSED, DWORD dwUser STG_UNUSED,
67 DWORD dw1 STG_UNUSED, DWORD d STG_UNUSED)
69 handle_tick(int unused STG_UNUSED)
78 /* so we can get a rough indication of the current time at any point
79 * without having to call gettimeofday() (see Select.c):
81 ticks_since_timestamp++;
83 ticks_to_ctxt_switch--;
84 if (ticks_to_ctxt_switch <= 0) {
85 ticks_to_ctxt_switch = RtsFlags.ConcFlags.ctxtSwitchTicks;
86 context_switch = 1; /* schedule a context switch */
92 * Handling timer events under cygwin32 is not done with signal/setitimer.
93 * Instead of the two steps of first registering a signal handler to handle
94 * \tr{SIGVTALRM} and then start generating them via @setitimer()@, we use
95 * the Multimedia API (MM) and its @timeSetEvent@. (Internally, the MM API
96 * creates a separate thread that will notify the main thread of timer
97 * expiry). -- SOF 7/96
99 * 11/98: if the cygwin DLL supports setitimer(), then use it instead.
102 #if defined(mingw32_TARGET_OS) || (defined(cygwin32_TARGET_OS) && !defined(HAVE_SETITIMER))
104 LPTIMECALLBACK vtalrm_cback;
107 initialize_virtual_timer(nat ms)
109 /* On Win32 setups that don't have support for
110 setitimer(), we use the MultiMedia API's timer
113 The delivery of ticks isn't free; the performance hit should be checked.
116 static unsigned int vtalrm_id;
119 delay = timeBeginPeriod(1);
120 if (delay == TIMERR_NOCANDO) { /* error of some sort. */
124 timeSetEvent(ms, /* event every `delay' milliseconds. */
125 1, /* precision is within 1 ms */
127 TIME_CALLBACK_FUNCTION, /* ordinary callback */
130 timeKillEvent(vtalrm_id);
140 initialize_virtual_timer(nat ms)
142 # ifndef HAVE_SETITIMER
143 /* fprintf(stderr, "No virtual timer on this system\n"); */
148 timestamp = getourtimeofday();
149 ticks_since_timestamp = 0;
151 it.it_value.tv_sec = ms / 1000;
152 it.it_value.tv_usec = 1000 * (ms - (1000 * it.it_value.tv_sec));
153 it.it_interval = it.it_value;
154 return (setitimer(ITIMER_VIRTUAL, &it, NULL));
158 #endif /* !cygwin32_TARGET_OS */
161 /* This is a potential POSIX version */
163 initialize_virtual_timer(nat ms)
166 struct itimerspec it;
169 timestamp = getourtimeofday();
170 ticks_since_timestamp = 0;
172 se.sigev_notify = SIGEV_SIGNAL;
173 se.sigev_signo = SIGVTALRM;
174 se.sigev_value.sival_int = SIGVTALRM;
175 if (timer_create(CLOCK_VIRTUAL, &se, &tid)) {
176 barf("can't create virtual timer");
178 it.it_value.tv_sec = ms / 1000;
179 it.it_value.tv_nsec = 1000000 * (ms - 1000 * it.it_value.tv_sec);
180 it.it_interval = it.it_value;
181 timer_settime(tid, TIMER_RELTIME, &it, NULL);
185 #if defined(mingw32_TARGET_OS) || (defined(cygwin32_TARGET_OS) && !defined(HAVE_SETITIMER))
187 install_vtalrm_handler(void)
189 vtalrm_cback = handle_tick;
195 install_vtalrm_handler(void)
197 struct sigaction action;
199 action.sa_handler = handle_tick;
201 sigemptyset(&action.sa_mask);
204 return sigaction(SIGVTALRM, &action, NULL);
208 block_vtalrm_signal(void)
212 sigemptyset(&signals);
213 sigaddset(&signals, SIGVTALRM);
215 (void) sigprocmask(SIG_BLOCK, &signals, NULL);
219 unblock_vtalrm_signal(void)
223 sigemptyset(&signals);
224 sigaddset(&signals, SIGVTALRM);
226 (void) sigprocmask(SIG_UNBLOCK, &signals, NULL);
230 /* gettimeofday() takes around 1us on our 500MHz PIII. Since we're
231 * only calling it 50 times/s, it shouldn't have any great impact.
233 #if !defined(mingw32_TARGET_OS)
235 getourtimeofday(void)
238 gettimeofday(&tv, (struct timezone *) NULL);
239 return (tv.tv_sec * TICK_FREQUENCY +
240 tv.tv_usec * TICK_FREQUENCY / 1000000);
244 getourtimeofday(void)
246 return ((unsigned int)GetTickCount() * TICK_FREQUENCY) / 1000;