Calculate the total memory allocated on a per-capability basis
[ghc.git] / rts / Capability.h
1 /* ---------------------------------------------------------------------------
2 *
3 * (c) The GHC Team, 2001-2006
4 *
5 * Capabilities
6 *
7 * For details on the high-level design, see
8 * http://hackage.haskell.org/trac/ghc/wiki/Commentary/Rts/Scheduler
9 *
10 * A Capability holds all the state an OS thread/task needs to run
11 * Haskell code: its STG registers, a pointer to its TSO, a nursery
12 * etc. During STG execution, a pointer to the Capabilitity is kept in
13 * a register (BaseReg).
14 *
15 * Only in a THREADED_RTS build will there be multiple capabilities,
16 * in the non-threaded RTS there is one global capability, called
17 * MainCapability.
18 *
19 * --------------------------------------------------------------------------*/
20
21 #ifndef CAPABILITY_H
22 #define CAPABILITY_H
23
24 #include "sm/GC.h" // for evac_fn
25 #include "Task.h"
26 #include "Sparks.h"
27
28 #include "BeginPrivate.h"
29
30 struct Capability_ {
31 // State required by the STG virtual machine when running Haskell
32 // code. During STG execution, the BaseReg register always points
33 // to the StgRegTable of the current Capability (&cap->r).
34 StgFunTable f;
35 StgRegTable r;
36
37 nat no; // capability number.
38
39 // The Task currently holding this Capability. This task has
40 // exclusive access to the contents of this Capability (apart from
41 // returning_tasks_hd/returning_tasks_tl).
42 // Locks required: cap->lock.
43 Task *running_task;
44
45 // true if this Capability is running Haskell code, used for
46 // catching unsafe call-ins.
47 rtsBool in_haskell;
48
49 // Has there been any activity on this Capability since the last GC?
50 nat idle;
51
52 rtsBool disabled;
53
54 // The run queue. The Task owning this Capability has exclusive
55 // access to its run queue, so can wake up threads without
56 // taking a lock, and the common path through the scheduler is
57 // also lock-free.
58 StgTSO *run_queue_hd;
59 StgTSO *run_queue_tl;
60
61 // Tasks currently making safe foreign calls. Doubly-linked.
62 // When returning, a task first acquires the Capability before
63 // removing itself from this list, so that the GC can find all
64 // the suspended TSOs easily. Hence, when migrating a Task from
65 // the returning_tasks list, we must also migrate its entry from
66 // this list.
67 InCall *suspended_ccalls;
68
69 // One mutable list per generation, so we don't need to take any
70 // locks when updating an old-generation thunk. This also lets us
71 // keep track of which closures this CPU has been mutating, so we
72 // can traverse them using the right thread during GC and avoid
73 // unnecessarily moving the data from one cache to another.
74 bdescr **mut_lists;
75 bdescr **saved_mut_lists; // tmp use during GC
76
77 // block for allocating pinned objects into
78 bdescr *pinned_object_block;
79 // full pinned object blocks allocated since the last GC
80 bdescr *pinned_object_blocks;
81
82 // Context switch flag. When non-zero, this means: stop running
83 // Haskell code, and switch threads.
84 int context_switch;
85
86 // Interrupt flag. Like the context_switch flag, this also
87 // indicates that we should stop running Haskell code, but we do
88 // *not* switch threads. This is used to stop a Capability in
89 // order to do GC, for example.
90 //
91 // The interrupt flag is always reset before we start running
92 // Haskell code, unlike the context_switch flag which is only
93 // reset after we have executed the context switch.
94 int interrupt;
95
96 #if defined(THREADED_RTS)
97 // Worker Tasks waiting in the wings. Singly-linked.
98 Task *spare_workers;
99 nat n_spare_workers; // count of above
100
101 // This lock protects:
102 // running_task
103 // returning_tasks_{hd,tl}
104 // wakeup_queue
105 // inbox
106 Mutex lock;
107
108 // Tasks waiting to return from a foreign call, or waiting to make
109 // a new call-in using this Capability (NULL if empty).
110 // NB. this field needs to be modified by tasks other than the
111 // running_task, so it requires cap->lock to modify. A task can
112 // check whether it is NULL without taking the lock, however.
113 Task *returning_tasks_hd; // Singly-linked, with head/tail
114 Task *returning_tasks_tl;
115
116 // Messages, or END_TSO_QUEUE.
117 // Locks required: cap->lock
118 Message *inbox;
119
120 SparkPool *sparks;
121
122 // Stats on spark creation/conversion
123 SparkCounters spark_stats;
124 #endif
125 // Total words allocated by this cap since rts start
126 lnat total_allocated;
127
128 // Per-capability STM-related data
129 StgTVarWatchQueue *free_tvar_watch_queues;
130 StgInvariantCheckQueue *free_invariant_check_queues;
131 StgTRecChunk *free_trec_chunks;
132 StgTRecHeader *free_trec_headers;
133 nat transaction_tokens;
134 } // typedef Capability is defined in RtsAPI.h
135 // Capabilities are stored in an array, so make sure that adjacent
136 // Capabilities don't share any cache-lines:
137 #ifndef mingw32_HOST_OS
138 ATTRIBUTE_ALIGNED(64)
139 #endif
140 ;
141
142
143 #if defined(THREADED_RTS)
144 #define ASSERT_TASK_ID(task) ASSERT(task->id == osThreadId())
145 #else
146 #define ASSERT_TASK_ID(task) /*empty*/
147 #endif
148
149 // These properties should be true when a Task is holding a Capability
150 #define ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task) \
151 ASSERT(cap->running_task != NULL && cap->running_task == task); \
152 ASSERT(task->cap == cap); \
153 ASSERT_PARTIAL_CAPABILITY_INVARIANTS(cap,task)
154
155 // Sometimes a Task holds a Capability, but the Task is not associated
156 // with that Capability (ie. task->cap != cap). This happens when
157 // (a) a Task holds multiple Capabilities, and (b) when the current
158 // Task is bound, its thread has just blocked, and it may have been
159 // moved to another Capability.
160 #define ASSERT_PARTIAL_CAPABILITY_INVARIANTS(cap,task) \
161 ASSERT(cap->run_queue_hd == END_TSO_QUEUE ? \
162 cap->run_queue_tl == END_TSO_QUEUE : 1); \
163 ASSERT(myTask() == task); \
164 ASSERT_TASK_ID(task);
165
166 #if defined(THREADED_RTS)
167 rtsBool checkSparkCountInvariant (void);
168 #endif
169
170 // Converts a *StgRegTable into a *Capability.
171 //
172 INLINE_HEADER Capability *
173 regTableToCapability (StgRegTable *reg)
174 {
175 return (Capability *)((void *)((unsigned char*)reg - STG_FIELD_OFFSET(Capability,r)));
176 }
177
178 // Initialise the available capabilities.
179 //
180 void initCapabilities (void);
181
182 // Add and initialise more Capabilities
183 //
184 Capability * moreCapabilities (nat from, nat to);
185
186 // Release a capability. This is called by a Task that is exiting
187 // Haskell to make a foreign call, or in various other cases when we
188 // want to relinquish a Capability that we currently hold.
189 //
190 // ASSUMES: cap->running_task is the current Task.
191 //
192 #if defined(THREADED_RTS)
193 void releaseCapability (Capability* cap);
194 void releaseAndWakeupCapability (Capability* cap);
195 void releaseCapability_ (Capability* cap, rtsBool always_wakeup);
196 // assumes cap->lock is held
197 #else
198 // releaseCapability() is empty in non-threaded RTS
199 INLINE_HEADER void releaseCapability (Capability* cap STG_UNUSED) {};
200 INLINE_HEADER void releaseAndWakeupCapability (Capability* cap STG_UNUSED) {};
201 INLINE_HEADER void releaseCapability_ (Capability* cap STG_UNUSED,
202 rtsBool always_wakeup STG_UNUSED) {};
203 #endif
204
205 // declared in includes/rts/Threads.h:
206 // extern Capability MainCapability;
207
208 // declared in includes/rts/Threads.h:
209 // extern nat n_capabilities;
210
211 extern nat enabled_capabilities;
212
213 // Array of all the capabilities
214 //
215 extern Capability *capabilities;
216
217 // The Capability that was last free. Used as a good guess for where
218 // to assign new threads.
219 //
220 extern Capability *last_free_capability;
221
222 //
223 // Indicates that the RTS wants to synchronise all the Capabilities
224 // for some reason. All Capabilities should stop and return to the
225 // scheduler.
226 //
227 #define SYNC_GC_SEQ 1
228 #define SYNC_GC_PAR 2
229 #define SYNC_OTHER 3
230 extern volatile StgWord pending_sync;
231
232 // Acquires a capability at a return point. If *cap is non-NULL, then
233 // this is taken as a preference for the Capability we wish to
234 // acquire.
235 //
236 // OS threads waiting in this function get priority over those waiting
237 // in waitForCapability().
238 //
239 // On return, *cap is non-NULL, and points to the Capability acquired.
240 //
241 void waitForReturnCapability (Capability **cap/*in/out*/, Task *task);
242
243 EXTERN_INLINE void recordMutableCap (StgClosure *p, Capability *cap, nat gen);
244
245 EXTERN_INLINE void recordClosureMutated (Capability *cap, StgClosure *p);
246
247 #if defined(THREADED_RTS)
248
249 // Gives up the current capability IFF there is a higher-priority
250 // thread waiting for it. This happens in one of two ways:
251 //
252 // (a) we are passing the capability to another OS thread, so
253 // that it can run a bound Haskell thread, or
254 //
255 // (b) there is an OS thread waiting to return from a foreign call
256 //
257 // On return: *pCap is NULL if the capability was released. The
258 // current task should then re-acquire it using waitForCapability().
259 //
260 void yieldCapability (Capability** pCap, Task *task);
261
262 // Acquires a capability for doing some work.
263 //
264 // On return: pCap points to the capability.
265 //
266 void waitForCapability (Task *task, Mutex *mutex, Capability **pCap);
267
268 // Wakes up a worker thread on just one Capability, used when we
269 // need to service some global event.
270 //
271 void prodOneCapability (void);
272 void prodCapability (Capability *cap, Task *task);
273
274 // Similar to prodOneCapability(), but prods all of them.
275 //
276 void prodAllCapabilities (void);
277
278 // Attempt to gain control of a Capability if it is free.
279 //
280 rtsBool tryGrabCapability (Capability *cap, Task *task);
281
282 // Try to find a spark to run
283 //
284 StgClosure *findSpark (Capability *cap);
285
286 // True if any capabilities have sparks
287 //
288 rtsBool anySparks (void);
289
290 INLINE_HEADER rtsBool emptySparkPoolCap (Capability *cap);
291 INLINE_HEADER nat sparkPoolSizeCap (Capability *cap);
292 INLINE_HEADER void discardSparksCap (Capability *cap);
293
294 #else // !THREADED_RTS
295
296 // Grab a capability. (Only in the non-threaded RTS; in the threaded
297 // RTS one of the waitFor*Capability() functions must be used).
298 //
299 extern void grabCapability (Capability **pCap);
300
301 #endif /* !THREADED_RTS */
302
303 // Waits for a capability to drain of runnable threads and workers,
304 // and then acquires it. Used at shutdown time.
305 //
306 void shutdownCapability (Capability *cap, Task *task, rtsBool wait_foreign);
307
308 // Shut down all capabilities.
309 //
310 void shutdownCapabilities(Task *task, rtsBool wait_foreign);
311
312 // cause all capabilities to context switch as soon as possible.
313 void contextSwitchAllCapabilities(void);
314 INLINE_HEADER void contextSwitchCapability(Capability *cap);
315
316 // cause all capabilities to stop running Haskell code and return to
317 // the scheduler as soon as possible.
318 void interruptAllCapabilities(void);
319 INLINE_HEADER void interruptCapability(Capability *cap);
320
321 // Free all capabilities
322 void freeCapabilities (void);
323
324 // For the GC:
325 void markCapability (evac_fn evac, void *user, Capability *cap,
326 rtsBool no_mark_sparks USED_IF_THREADS);
327
328 void markCapabilities (evac_fn evac, void *user);
329
330 void traverseSparkQueues (evac_fn evac, void *user);
331
332 /* -----------------------------------------------------------------------------
333 Messages
334 -------------------------------------------------------------------------- */
335
336 #ifdef THREADED_RTS
337
338 INLINE_HEADER rtsBool emptyInbox(Capability *cap);
339
340 #endif // THREADED_RTS
341
342 /* -----------------------------------------------------------------------------
343 * INLINE functions... private below here
344 * -------------------------------------------------------------------------- */
345
346 EXTERN_INLINE void
347 recordMutableCap (StgClosure *p, Capability *cap, nat gen)
348 {
349 bdescr *bd;
350
351 // We must own this Capability in order to modify its mutable list.
352 // ASSERT(cap->running_task == myTask());
353 // NO: assertion is violated by performPendingThrowTos()
354 bd = cap->mut_lists[gen];
355 if (bd->free >= bd->start + BLOCK_SIZE_W) {
356 bdescr *new_bd;
357 new_bd = allocBlock_lock();
358 new_bd->link = bd;
359 bd = new_bd;
360 cap->mut_lists[gen] = bd;
361 }
362 *bd->free++ = (StgWord)p;
363 }
364
365 EXTERN_INLINE void
366 recordClosureMutated (Capability *cap, StgClosure *p)
367 {
368 bdescr *bd;
369 bd = Bdescr((StgPtr)p);
370 if (bd->gen_no != 0) recordMutableCap(p,cap,bd->gen_no);
371 }
372
373
374 #if defined(THREADED_RTS)
375 INLINE_HEADER rtsBool
376 emptySparkPoolCap (Capability *cap)
377 { return looksEmpty(cap->sparks); }
378
379 INLINE_HEADER nat
380 sparkPoolSizeCap (Capability *cap)
381 { return sparkPoolSize(cap->sparks); }
382
383 INLINE_HEADER void
384 discardSparksCap (Capability *cap)
385 { discardSparks(cap->sparks); }
386 #endif
387
388 INLINE_HEADER void
389 stopCapability (Capability *cap)
390 {
391 // setting HpLim to NULL tries to make the next heap check will
392 // fail, which will cause the thread to return to the scheduler.
393 // It may not work - the thread might be updating HpLim itself
394 // at the same time - so we also have the context_switch/interrupted
395 // flags as a sticky way to tell the thread to stop.
396 cap->r.rHpLim = NULL;
397 }
398
399 INLINE_HEADER void
400 interruptCapability (Capability *cap)
401 {
402 stopCapability(cap);
403 cap->interrupt = 1;
404 }
405
406 INLINE_HEADER void
407 contextSwitchCapability (Capability *cap)
408 {
409 stopCapability(cap);
410 cap->context_switch = 1;
411 }
412
413 #ifdef THREADED_RTS
414
415 INLINE_HEADER rtsBool emptyInbox(Capability *cap)
416 {
417 return (cap->inbox == (Message*)END_TSO_QUEUE);
418 }
419
420 #endif
421
422 #include "EndPrivate.h"
423
424 #endif /* CAPABILITY_H */