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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 "PosixSource.h"
#include "Rts.h"
#include "Timer.h"
#include "Proftimer.h"
#include "Schedule.h"
#include "Ticker.h"
#include "Capability.h"
#include "RtsSignals.h"
/* ticks left before next pre-emptive context switch */
static int ticks_to_ctxt_switch = 0;
/* idle ticks left before GC allowed */
static int idle_ticks_to_gc = 0;
/* inter-idle GC ticks left before GC allowed */
static int inter_gc_ticks_to_gc = 0;
/*
* Function: handle_tick()
*
* At each occurrence of a tick, the OS timer will invoke
* handle_tick().
*/
static
void
handle_tick(int unused STG_UNUSED)
{
handleProfTick();
if (RtsFlags.ConcFlags.ctxtSwitchTicks > 0) {
ticks_to_ctxt_switch--;
if (ticks_to_ctxt_switch <= 0) {
ticks_to_ctxt_switch = RtsFlags.ConcFlags.ctxtSwitchTicks;
contextSwitchAllCapabilities(); /* schedule a context switch */
}
}
/*
* If we've been inactive for idleGCDelayTime (set by +RTS
* -I), tell the scheduler to wake up and do a GC, to check
* for threads that are deadlocked. However, ensure we wait
* at least interIdleGCWait (+RTS -Iw) between idle GCs.
*/
switch (recent_activity) {
case ACTIVITY_YES:
recent_activity = ACTIVITY_MAYBE_NO;
idle_ticks_to_gc = RtsFlags.GcFlags.idleGCDelayTime /
RtsFlags.MiscFlags.tickInterval;
break;
case ACTIVITY_MAYBE_NO:
if (idle_ticks_to_gc == 0 && inter_gc_ticks_to_gc == 0) {
if (RtsFlags.GcFlags.doIdleGC) {
recent_activity = ACTIVITY_INACTIVE;
inter_gc_ticks_to_gc = RtsFlags.GcFlags.interIdleGCWait /
RtsFlags.MiscFlags.tickInterval;
#if defined(THREADED_RTS)
wakeUpRts();
// The scheduler will call stopTimer() when it has done
// the GC.
#endif
} else {
recent_activity = ACTIVITY_DONE_GC;
// disable timer signals (see #1623, #5991, #9105)
// but only if we're not profiling (e.g. passed -h or -p RTS
// flags). If we are profiling we need to keep the timer active
// so that samples continue to be collected.
#if defined(PROFILING)
if (!(RtsFlags.ProfFlags.doHeapProfile
|| RtsFlags.CcFlags.doCostCentres)) {
stopTimer();
}
#else
stopTimer();
#endif
}
} else {
if (idle_ticks_to_gc) idle_ticks_to_gc--;
if (inter_gc_ticks_to_gc) inter_gc_ticks_to_gc--;
}
break;
default:
break;
}
}
// This global counter is used to allow multiple threads to stop the
// timer temporarily with a stopTimer()/startTimer() pair. If
// timer_enabled == 0 timer is enabled
// timer_disabled == N, N > 0 timer is disabled by N threads
// When timer_enabled makes a transition to 0, we enable the timer,
// and when it makes a transition to non-0 we disable it.
static StgWord timer_disabled;
void
initTimer(void)
{
initProfTimer();
if (RtsFlags.MiscFlags.tickInterval != 0) {
initTicker(RtsFlags.MiscFlags.tickInterval, handle_tick);
}
timer_disabled = 1;
}
void
startTimer(void)
{
if (atomic_dec(&timer_disabled) == 0) {
if (RtsFlags.MiscFlags.tickInterval != 0) {
startTicker();
}
}
}
void
stopTimer(void)
{
if (atomic_inc(&timer_disabled, 1) == 1) {
if (RtsFlags.MiscFlags.tickInterval != 0) {
stopTicker();
}
}
}
void
exitTimer (bool wait)
{
if (RtsFlags.MiscFlags.tickInterval != 0) {
exitTicker(wait);
}
}
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