1 /* -----------------------------------------------------------------------------
2 * $Id: Itimer.c,v 1.23 2001/08/14 13:40:09 sewardj 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.
21 /* This is not posix compliant. */
22 /* #include "PosixSource.h" */
27 #include "Proftimer.h"
30 /* As recommended in the autoconf manual */
31 # ifdef TIME_WITH_SYS_TIME
32 # include <sys/time.h>
35 # ifdef HAVE_SYS_TIME_H
36 # include <sys/time.h>
48 /* ticks left before next pre-emptive context switch */
49 int ticks_to_ctxt_switch = 0;
51 /* -----------------------------------------------------------------------------
54 We use the ticker for time profiling.
56 SMP note: this signal could be delivered to *any* thread. We have
57 to ensure that it doesn't matter which thread actually runs the
59 -------------------------------------------------------------------------- */
63 #if defined(mingw32_TARGET_OS) || (defined(cygwin32_TARGET_OS) && !defined(HAVE_SETITIMER))
65 handle_tick(UINT uID STG_UNUSED, UINT uMsg STG_UNUSED, DWORD dwUser STG_UNUSED,
66 DWORD dw1 STG_UNUSED, DWORD d STG_UNUSED)
68 handle_tick(int unused STG_UNUSED)
77 /* so we can get a rough indication of the current time at any point
78 * without having to call gettimeofday() (see Select.c):
80 ticks_since_timestamp++;
82 if (RtsFlags.ConcFlags.ctxtSwitchTicks > 0) {
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 */
93 * Handling timer events under cygwin32 is not done with signal/setitimer.
94 * Instead of the two steps of first registering a signal handler to handle
95 * \tr{SIGVTALRM} and then start generating them via @setitimer()@, we use
96 * the Multimedia API (MM) and its @timeSetEvent@. (Internally, the MM API
97 * creates a separate thread that will notify the main thread of timer
98 * expiry). -- SOF 7/96
100 * 11/98: if the cygwin DLL supports setitimer(), then use it instead.
103 #if defined(mingw32_TARGET_OS) || (defined(cygwin32_TARGET_OS) && !defined(HAVE_SETITIMER))
105 LPTIMECALLBACK vtalrm_cback;
108 initialize_virtual_timer(nat ms)
110 /* On Win32 setups that don't have support for
111 setitimer(), we use the MultiMedia API's timer
114 The delivery of ticks isn't free; the performance hit should be checked.
117 static unsigned int vtalrm_id;
120 delay = timeBeginPeriod(1);
121 if (delay == TIMERR_NOCANDO) { /* error of some sort. */
125 timeSetEvent(ms, /* event every `delay' milliseconds. */
126 1, /* precision is within 1 ms */
128 TIME_CALLBACK_FUNCTION, /* ordinary callback */
131 timeKillEvent(vtalrm_id);
141 initialize_virtual_timer(nat ms)
143 # ifndef HAVE_SETITIMER
144 /* fprintf(stderr, "No virtual timer on this system\n"); */
149 timestamp = getourtimeofday();
150 ticks_since_timestamp = 0;
152 it.it_value.tv_sec = ms / 1000;
153 it.it_value.tv_usec = 1000 * (ms - (1000 * it.it_value.tv_sec));
154 it.it_interval = it.it_value;
155 return (setitimer(ITIMER_VIRTUAL, &it, NULL));
159 #endif /* !cygwin32_TARGET_OS */
162 /* This is a potential POSIX version */
164 initialize_virtual_timer(nat ms)
167 struct itimerspec it;
170 timestamp = getourtimeofday();
171 ticks_since_timestamp = 0;
173 se.sigev_notify = SIGEV_SIGNAL;
174 se.sigev_signo = SIGVTALRM;
175 se.sigev_value.sival_int = SIGVTALRM;
176 if (timer_create(CLOCK_VIRTUAL, &se, &tid)) {
177 barf("can't create virtual timer");
179 it.it_value.tv_sec = ms / 1000;
180 it.it_value.tv_nsec = 1000000 * (ms - 1000 * it.it_value.tv_sec);
181 it.it_interval = it.it_value;
182 timer_settime(tid, TIMER_RELTIME, &it, NULL);
186 #if defined(mingw32_TARGET_OS) || (defined(cygwin32_TARGET_OS) && !defined(HAVE_SETITIMER))
188 install_vtalrm_handler(void)
190 vtalrm_cback = handle_tick;
196 install_vtalrm_handler(void)
198 struct sigaction action;
200 action.sa_handler = handle_tick;
202 sigemptyset(&action.sa_mask);
205 return sigaction(SIGVTALRM, &action, NULL);
209 block_vtalrm_signal(void)
213 sigemptyset(&signals);
214 sigaddset(&signals, SIGVTALRM);
216 (void) sigprocmask(SIG_BLOCK, &signals, NULL);
220 unblock_vtalrm_signal(void)
224 sigemptyset(&signals);
225 sigaddset(&signals, SIGVTALRM);
227 (void) sigprocmask(SIG_UNBLOCK, &signals, NULL);
231 /* gettimeofday() takes around 1us on our 500MHz PIII. Since we're
232 * only calling it 50 times/s, it shouldn't have any great impact.
234 #if !defined(mingw32_TARGET_OS)
236 getourtimeofday(void)
239 gettimeofday(&tv, (struct timezone *) NULL);
240 return (tv.tv_sec * TICK_FREQUENCY +
241 tv.tv_usec * TICK_FREQUENCY / 1000000);
245 getourtimeofday(void)
247 return ((unsigned int)GetTickCount() * TICK_FREQUENCY) / 1000;