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/* -----------------------------------------------------------------------------
*
* (c) The GHC Team, 1995-2005
*
* Interval timer service for profiling and pre-emptive scheduling.
*
* ---------------------------------------------------------------------------*/
/*
* The interval timer is used for profiling and for context switching in the
* threaded build.
*
* This file defines the platform-independent view of interval timing, relying
* on platform-specific services to install and run the timers.
*
*/
#include "Rts.h"
#include "RtsFlags.h"
#include "Proftimer.h"
#include "Schedule.h"
#include "Timer.h"
#include "Ticker.h"
#include "Capability.h"
/* ticks left before next pre-emptive context switch */
static int ticks_to_ctxt_switch = 0;
#if defined(THREADED_RTS)
/* idle ticks left before we perform a GC */
static int ticks_to_gc = 0;
#endif
/*
* Function: handle_tick()
*
* At each occurrence of a tick, the OS timer will invoke
* handle_tick().
*/
static
void
handle_tick(int unused STG_UNUSED)
{
#ifdef PROFILING
handleProfTick();
#endif
if (RtsFlags.ConcFlags.ctxtSwitchTicks > 0) {
ticks_to_ctxt_switch--;
if (ticks_to_ctxt_switch <= 0) {
ticks_to_ctxt_switch = RtsFlags.ConcFlags.ctxtSwitchTicks;
context_switch = 1; /* schedule a context switch */
}
}
#if defined(THREADED_RTS)
/*
* If we've been inactive for idleGCDelayTicks (set by +RTS
* -I), tell the scheduler to wake up and do a GC, to check
* for threads that are deadlocked.
*/
switch (recent_activity) {
case ACTIVITY_YES:
recent_activity = ACTIVITY_MAYBE_NO;
ticks_to_gc = RtsFlags.GcFlags.idleGCDelayTicks;
break;
case ACTIVITY_MAYBE_NO:
if (ticks_to_gc == 0) break; /* 0 ==> no idle GC */
ticks_to_gc--;
if (ticks_to_gc == 0) {
ticks_to_gc = RtsFlags.GcFlags.idleGCDelayTicks;
recent_activity = ACTIVITY_INACTIVE;
blackholes_need_checking = rtsTrue;
/* hack: re-use the blackholes_need_checking flag */
/* ToDo: this doesn't work. Can't invoke
* pthread_cond_signal from a signal handler.
* Furthermore, we can't prod a capability that we
* might be holding. What can we do?
*/
prodOneCapability();
}
break;
default:
break;
}
#endif
}
int
startTimer(nat ms)
{
#ifdef PROFILING
initProfTimer();
#endif
return startTicker(ms, handle_tick);
}
int
stopTimer()
{
return stopTicker();
}
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