RTS tidyup sweep, first phase
[ghc.git] / rts / Timer.c
1 /* -----------------------------------------------------------------------------
2 *
3 * (c) The GHC Team, 1995-2005
4 *
5 * Interval timer service for profiling and pre-emptive scheduling.
6 *
7 * ---------------------------------------------------------------------------*/
8
9 /*
10 * The interval timer is used for profiling and for context switching in the
11 * threaded build.
12 *
13 * This file defines the platform-independent view of interval timing, relying
14 * on platform-specific services to install and run the timers.
15 *
16 */
17
18 #include "PosixSource.h"
19 #include "Rts.h"
20
21 #include "Timer.h"
22 #include "Proftimer.h"
23 #include "Schedule.h"
24 #include "Ticker.h"
25 #include "Capability.h"
26 #include "RtsSignals.h"
27
28 /* ticks left before next pre-emptive context switch */
29 static int ticks_to_ctxt_switch = 0;
30
31 #if defined(THREADED_RTS)
32 /* idle ticks left before we perform a GC */
33 static int ticks_to_gc = 0;
34 #endif
35
36 /*
37 * Function: handle_tick()
38 *
39 * At each occurrence of a tick, the OS timer will invoke
40 * handle_tick().
41 */
42 static
43 void
44 handle_tick(int unused STG_UNUSED)
45 {
46 handleProfTick();
47 if (RtsFlags.ConcFlags.ctxtSwitchTicks > 0) {
48 ticks_to_ctxt_switch--;
49 if (ticks_to_ctxt_switch <= 0) {
50 ticks_to_ctxt_switch = RtsFlags.ConcFlags.ctxtSwitchTicks;
51 setContextSwitches(); /* schedule a context switch */
52 }
53 }
54
55 #if defined(THREADED_RTS)
56 /*
57 * If we've been inactive for idleGCDelayTime (set by +RTS
58 * -I), tell the scheduler to wake up and do a GC, to check
59 * for threads that are deadlocked.
60 */
61 switch (recent_activity) {
62 case ACTIVITY_YES:
63 recent_activity = ACTIVITY_MAYBE_NO;
64 ticks_to_gc = RtsFlags.GcFlags.idleGCDelayTime /
65 RtsFlags.MiscFlags.tickInterval;
66 break;
67 case ACTIVITY_MAYBE_NO:
68 if (ticks_to_gc == 0) {
69 /* 0 ==> no idle GC */
70 recent_activity = ACTIVITY_DONE_GC;
71 // disable timer signals (see #1623)
72 stopTimer();
73 } else {
74 ticks_to_gc--;
75 if (ticks_to_gc == 0) {
76 ticks_to_gc = RtsFlags.GcFlags.idleGCDelayTime /
77 RtsFlags.MiscFlags.tickInterval;
78 recent_activity = ACTIVITY_INACTIVE;
79 blackholes_need_checking = rtsTrue;
80 /* hack: re-use the blackholes_need_checking flag */
81 wakeUpRts();
82 }
83 }
84 break;
85 default:
86 break;
87 }
88 #endif
89 }
90
91 void
92 initTimer(void)
93 {
94 initProfTimer();
95 if (RtsFlags.MiscFlags.tickInterval != 0) {
96 initTicker(RtsFlags.MiscFlags.tickInterval, handle_tick);
97 }
98 }
99
100 void
101 startTimer(void)
102 {
103 if (RtsFlags.MiscFlags.tickInterval != 0) {
104 startTicker();
105 }
106 }
107
108 void
109 stopTimer(void)
110 {
111 if (RtsFlags.MiscFlags.tickInterval != 0) {
112 stopTicker();
113 }
114 }
115
116 void
117 exitTimer(void)
118 {
119 if (RtsFlags.MiscFlags.tickInterval != 0) {
120 exitTicker();
121 }
122 }