1 | #pragma once |
---|
2 | |
---|
3 | #include <locks.hfa> |
---|
4 | #include <limits.hfa> |
---|
5 | #include <list.hfa> |
---|
6 | #include <kernel.hfa> |
---|
7 | #include <vector2.hfa> |
---|
8 | |
---|
9 | #ifdef __CFA_DEBUG__ |
---|
10 | #define CFA_DEBUG( stmt ) stmt |
---|
11 | #else |
---|
12 | #define CFA_DEBUG( stmt ) |
---|
13 | #endif // CFA_DEBUG |
---|
14 | |
---|
15 | // Define the default number of processors created in the executor. Must be greater than 0. |
---|
16 | #define __DEFAULT_EXECUTOR_PROCESSORS__ 2 |
---|
17 | |
---|
18 | // Define the default number of threads created in the executor. Must be greater than 0. |
---|
19 | #define __DEFAULT_EXECUTOR_WORKERS__ 2 |
---|
20 | |
---|
21 | // Define the default number of executor request-queues (mailboxes) written to by actors and serviced by the |
---|
22 | // actor-executor threads. Must be greater than 0. |
---|
23 | #define __DEFAULT_EXECUTOR_RQUEUES__ 2 |
---|
24 | |
---|
25 | // Define if executor is created in a separate cluster |
---|
26 | #define __DEFAULT_EXECUTOR_SEPCLUS__ false |
---|
27 | |
---|
28 | #define __STEAL 1 // workstealing toggle. Disjoint from toggles above |
---|
29 | |
---|
30 | // whether to steal work or to steal a queue Only applicable if __STEAL == 1 |
---|
31 | #define __STEAL_WORK 0 |
---|
32 | |
---|
33 | // heuristic selection (only set one to be 1) |
---|
34 | #define __RAND_QUEUE 1 |
---|
35 | #define __RAND_WORKER 0 |
---|
36 | |
---|
37 | // show stealing stats |
---|
38 | // #define __STEAL_STATS |
---|
39 | |
---|
40 | // forward decls |
---|
41 | struct actor; |
---|
42 | struct message; |
---|
43 | |
---|
44 | enum Allocation { Nodelete, Delete, Destroy, Finished }; // allocation status |
---|
45 | |
---|
46 | typedef Allocation (*__receive_fn)(actor &, message &); |
---|
47 | struct request { |
---|
48 | actor * receiver; |
---|
49 | message * msg; |
---|
50 | __receive_fn fn; |
---|
51 | bool stop; |
---|
52 | }; |
---|
53 | |
---|
54 | static inline void ?{}( request & this ) { this.stop = true; } // default ctor makes a sentinel |
---|
55 | static inline void ?{}( request & this, actor * receiver, message * msg, __receive_fn fn ) { |
---|
56 | this.receiver = receiver; |
---|
57 | this.msg = msg; |
---|
58 | this.fn = fn; |
---|
59 | this.stop = false; |
---|
60 | } |
---|
61 | static inline void ?{}( request & this, request & copy ) { |
---|
62 | this.receiver = copy.receiver; |
---|
63 | this.msg = copy.msg; |
---|
64 | this.fn = copy.fn; |
---|
65 | this.stop = copy.stop; |
---|
66 | } |
---|
67 | |
---|
68 | // hybrid data structure. Copies until buffer is full and then allocates for intrusive list |
---|
69 | struct copy_queue { |
---|
70 | request * buffer; |
---|
71 | size_t count, buffer_size, index, utilized, last_size; |
---|
72 | }; |
---|
73 | static inline void ?{}( copy_queue & this ) {} |
---|
74 | static inline void ?{}( copy_queue & this, size_t buf_size ) with(this) { |
---|
75 | buffer_size = buf_size; |
---|
76 | buffer = aalloc( buffer_size ); |
---|
77 | count = 0; |
---|
78 | utilized = 0; |
---|
79 | index = 0; |
---|
80 | last_size = 0; |
---|
81 | } |
---|
82 | static inline void ^?{}( copy_queue & this ) with(this) { adelete(buffer); } |
---|
83 | |
---|
84 | static inline void insert( copy_queue & this, request & elem ) with(this) { |
---|
85 | if ( count >= buffer_size ) { // increase arr size |
---|
86 | last_size = buffer_size; |
---|
87 | buffer_size = 2 * buffer_size; |
---|
88 | buffer = realloc( buffer, sizeof( request ) * buffer_size ); |
---|
89 | /* paranoid */ verify( buffer ); |
---|
90 | } |
---|
91 | buffer[count]{ elem }; // C_TODO: change to memcpy |
---|
92 | // memcpy( &buffer[count], &elem, sizeof(request) ); |
---|
93 | count++; |
---|
94 | } |
---|
95 | |
---|
96 | // once you start removing you need to remove all elements |
---|
97 | // it is not supported to call insert() before the list is fully empty |
---|
98 | static inline request & remove( copy_queue & this ) with(this) { |
---|
99 | if ( count > 0 ) { |
---|
100 | count--; |
---|
101 | size_t old_idx = index; |
---|
102 | index = count == 0 ? 0 : index + 1; |
---|
103 | return buffer[old_idx]; |
---|
104 | } |
---|
105 | request * ret = 0p; |
---|
106 | return *0p; |
---|
107 | } |
---|
108 | |
---|
109 | // try to reclaim some memory |
---|
110 | static inline void reclaim( copy_queue & this ) with(this) { |
---|
111 | if ( utilized >= last_size || buffer_size <= 4 ) { utilized = 0; return; } |
---|
112 | utilized = 0; |
---|
113 | buffer_size--; |
---|
114 | buffer = realloc( buffer, sizeof( request ) * buffer_size ); // try to reclaim some memory |
---|
115 | } |
---|
116 | |
---|
117 | static inline bool isEmpty( copy_queue & this ) with(this) { return count == 0; } |
---|
118 | |
---|
119 | static size_t __buffer_size = 10; // C_TODO: rework this to be passed from executor through ctors (no need for global) |
---|
120 | struct work_queue { |
---|
121 | __spinlock_t mutex_lock; |
---|
122 | copy_queue owned_queue; |
---|
123 | copy_queue * c_queue; |
---|
124 | volatile bool being_processed; |
---|
125 | }; // work_queue |
---|
126 | static inline void ?{}( work_queue & this ) with(this) { |
---|
127 | owned_queue{ __buffer_size }; |
---|
128 | c_queue = &owned_queue; |
---|
129 | being_processed = false; |
---|
130 | } |
---|
131 | |
---|
132 | static inline void insert( work_queue & this, request & elem ) with(this) { |
---|
133 | lock( mutex_lock __cfaabi_dbg_ctx2 ); |
---|
134 | insert( *c_queue, elem ); |
---|
135 | unlock( mutex_lock ); |
---|
136 | } // insert |
---|
137 | |
---|
138 | static inline void transfer( work_queue & this, copy_queue ** transfer_to, work_queue ** queue_arr, unsigned int idx ) with(this) { |
---|
139 | lock( mutex_lock __cfaabi_dbg_ctx2 ); |
---|
140 | #if __STEAL |
---|
141 | |
---|
142 | #if __STEAL_WORK |
---|
143 | if ( unlikely( being_processed ) ) |
---|
144 | #else |
---|
145 | // check if queue has been stolen out from under us between |
---|
146 | // transfer() call and lock acquire C_TODO: maybe just use new queue! |
---|
147 | if ( unlikely( being_processed || queue_arr[idx] != &this ) ) |
---|
148 | #endif // __STEAL_WORK |
---|
149 | { |
---|
150 | unlock( mutex_lock ); |
---|
151 | return; |
---|
152 | } |
---|
153 | |
---|
154 | being_processed = c_queue->count != 0; |
---|
155 | #endif // __STEAL |
---|
156 | |
---|
157 | c_queue->utilized = c_queue->count; |
---|
158 | |
---|
159 | // swap copy queue ptrs |
---|
160 | copy_queue * temp = *transfer_to; |
---|
161 | *transfer_to = c_queue; |
---|
162 | c_queue = temp; |
---|
163 | unlock( mutex_lock ); |
---|
164 | } // transfer |
---|
165 | |
---|
166 | thread worker { |
---|
167 | work_queue ** request_queues; |
---|
168 | copy_queue * current_queue; |
---|
169 | worker ** worker_arr; // C_TODO: change n_workers, n_queues,worker_arr to just be pulled from ptr to executor |
---|
170 | request & req; |
---|
171 | unsigned int start, range, empty_count, n_workers, n_queues, id; |
---|
172 | #ifdef __STEAL_STATS |
---|
173 | unsigned int try_steal, stolen; |
---|
174 | #endif |
---|
175 | }; |
---|
176 | |
---|
177 | #ifdef __STEAL_STATS |
---|
178 | unsigned int total_tries = 0, total_stolen = 0, total_workers; |
---|
179 | #endif |
---|
180 | static inline void ?{}( worker & this, cluster & clu, work_queue ** request_queues, copy_queue * current_queue, unsigned int start, |
---|
181 | unsigned int range, worker ** worker_arr, unsigned int n_workers, unsigned int n_queues, unsigned int id ) { |
---|
182 | ((thread &)this){ clu }; |
---|
183 | this.request_queues = request_queues; |
---|
184 | this.current_queue = current_queue; |
---|
185 | this.start = start; |
---|
186 | this.range = range; |
---|
187 | this.empty_count = 0; |
---|
188 | this.n_workers = n_workers; |
---|
189 | this.worker_arr = worker_arr; |
---|
190 | this.n_queues = n_queues; |
---|
191 | this.id = id; |
---|
192 | #ifdef __STEAL_STATS |
---|
193 | this.try_steal = 0; |
---|
194 | this.stolen = 0; |
---|
195 | total_workers = n_workers; |
---|
196 | #endif |
---|
197 | } |
---|
198 | static inline void ^?{}( worker & mutex this ) with(this) { |
---|
199 | // delete( current_queue ); |
---|
200 | #ifdef __STEAL_STATS |
---|
201 | __atomic_add_fetch(&total_tries, try_steal, __ATOMIC_SEQ_CST); |
---|
202 | __atomic_add_fetch(&total_stolen, stolen, __ATOMIC_SEQ_CST); |
---|
203 | if (__atomic_sub_fetch(&total_workers, 1, __ATOMIC_SEQ_CST) == 0) |
---|
204 | printf("steal attempts: %u, steals: %u\n", total_tries, total_stolen); |
---|
205 | #endif |
---|
206 | } |
---|
207 | |
---|
208 | struct executor { |
---|
209 | cluster * cluster; // if workers execute on separate cluster |
---|
210 | processor ** processors; // array of virtual processors adding parallelism for workers |
---|
211 | work_queue * request_queues; // master array of work request queues |
---|
212 | copy_queue * local_queues; // array of all worker local queues to avoid deletion race |
---|
213 | work_queue ** worker_req_queues; // secondary array of work queues to allow for swapping |
---|
214 | worker ** workers; // array of workers executing work requests |
---|
215 | unsigned int nprocessors, nworkers, nrqueues; // number of processors/threads/request queues |
---|
216 | bool seperate_clus; // use same or separate cluster for executor |
---|
217 | }; // executor |
---|
218 | |
---|
219 | static inline void ?{}( executor & this, unsigned int nprocessors, unsigned int nworkers, unsigned int nrqueues, bool seperate_clus, size_t buf_size ) with(this) { |
---|
220 | if ( nrqueues < nworkers ) abort( "nrqueues needs to be >= nworkers\n" ); |
---|
221 | __buffer_size = buf_size; |
---|
222 | this.nprocessors = nprocessors; |
---|
223 | this.nworkers = nworkers; |
---|
224 | this.nrqueues = nrqueues; |
---|
225 | this.seperate_clus = seperate_clus; |
---|
226 | |
---|
227 | if ( seperate_clus ) { |
---|
228 | cluster = alloc(); |
---|
229 | (*cluster){}; |
---|
230 | } else cluster = active_cluster(); |
---|
231 | |
---|
232 | request_queues = aalloc( nrqueues ); |
---|
233 | worker_req_queues = aalloc( nrqueues ); |
---|
234 | for ( i; nrqueues ) { |
---|
235 | request_queues[i]{}; |
---|
236 | worker_req_queues[i] = &request_queues[i]; |
---|
237 | } |
---|
238 | |
---|
239 | processors = aalloc( nprocessors ); |
---|
240 | for ( i; nprocessors ) |
---|
241 | (*(processors[i] = alloc())){ *cluster }; |
---|
242 | |
---|
243 | local_queues = aalloc( nworkers ); |
---|
244 | workers = alloc( nworkers ); |
---|
245 | unsigned int reqPerWorker = nrqueues / nworkers, extras = nrqueues % nworkers; |
---|
246 | for ( unsigned int i = 0, start = 0, range; i < nworkers; i += 1, start += range ) { |
---|
247 | local_queues[i]{ buf_size }; |
---|
248 | range = reqPerWorker + ( i < extras ? 1 : 0 ); |
---|
249 | (*(workers[i] = alloc())){ *cluster, worker_req_queues, &local_queues[i], start, range, workers, nworkers, nrqueues, i }; |
---|
250 | } // for |
---|
251 | } |
---|
252 | static inline void ?{}( executor & this, unsigned int nprocessors, unsigned int nworkers, unsigned int nrqueues, bool seperate_clus ) { this{ nprocessors, nworkers, nrqueues, seperate_clus, __buffer_size }; } |
---|
253 | static inline void ?{}( executor & this, unsigned int nprocessors, unsigned int nworkers, unsigned int nrqueues ) { this{ nprocessors, nworkers, nrqueues, __DEFAULT_EXECUTOR_SEPCLUS__ }; } |
---|
254 | static inline void ?{}( executor & this, unsigned int nprocessors, unsigned int nworkers ) { this{ nprocessors, nworkers, __DEFAULT_EXECUTOR_RQUEUES__ }; } |
---|
255 | static inline void ?{}( executor & this, unsigned int nprocessors ) { this{ nprocessors, __DEFAULT_EXECUTOR_WORKERS__ }; } |
---|
256 | static inline void ?{}( executor & this ) { this{ __DEFAULT_EXECUTOR_PROCESSORS__ }; } |
---|
257 | |
---|
258 | // C_TODO: once stealing is implemented make sure shutdown still works |
---|
259 | static inline void ^?{}( executor & this ) with(this) { |
---|
260 | #if __STEAL |
---|
261 | request sentinels[nrqueues]; |
---|
262 | for ( unsigned int i = 0; i < nrqueues; i++ ) { |
---|
263 | insert( request_queues[i], sentinels[i] ); // force eventually termination |
---|
264 | } // for |
---|
265 | #else |
---|
266 | request sentinels[nworkers]; |
---|
267 | unsigned int reqPerWorker = nrqueues / nworkers; |
---|
268 | for ( unsigned int i = 0, step = 0; i < nworkers; i += 1, step += reqPerWorker ) { |
---|
269 | insert( request_queues[step], sentinels[i] ); // force eventually termination |
---|
270 | } // for |
---|
271 | #endif |
---|
272 | |
---|
273 | for ( i; nworkers ) |
---|
274 | delete( workers[i] ); |
---|
275 | |
---|
276 | for ( i; nprocessors ) { |
---|
277 | delete( processors[i] ); |
---|
278 | } // for |
---|
279 | |
---|
280 | adelete( workers ); |
---|
281 | adelete( local_queues ); |
---|
282 | adelete( request_queues ); |
---|
283 | adelete( worker_req_queues ); |
---|
284 | adelete( processors ); |
---|
285 | if ( seperate_clus ) delete( cluster ); |
---|
286 | } |
---|
287 | |
---|
288 | // this is a static field of executor but have to forward decl for get_next_ticket |
---|
289 | static unsigned int __next_ticket = 0; |
---|
290 | |
---|
291 | static inline unsigned int get_next_ticket( executor & this ) with(this) { |
---|
292 | return __atomic_fetch_add( &__next_ticket, 1, __ATOMIC_SEQ_CST) % nrqueues; |
---|
293 | } // tickets |
---|
294 | |
---|
295 | // C_TODO: update globals in this file to be static fields once the project is done |
---|
296 | static executor * __actor_executor_ = 0p; |
---|
297 | static bool __actor_executor_passed = false; // was an executor passed to start_actor_system |
---|
298 | static unsigned long int __num_actors_; // number of actor objects in system |
---|
299 | static struct thread$ * __actor_executor_thd = 0p; // used to wake executor after actors finish |
---|
300 | struct actor { |
---|
301 | unsigned long int ticket; // executor-queue handle to provide FIFO message execution |
---|
302 | Allocation allocation_; // allocation action |
---|
303 | }; |
---|
304 | |
---|
305 | static inline void ?{}( actor & this ) { |
---|
306 | // Once an actor is allocated it must be sent a message or the actor system cannot stop. Hence, its receive |
---|
307 | // member must be called to end it |
---|
308 | verifyf( __actor_executor_, "Creating actor before calling start_actor_system()." ); |
---|
309 | this.allocation_ = Nodelete; |
---|
310 | this.ticket = get_next_ticket( *__actor_executor_ ); |
---|
311 | __atomic_fetch_add( &__num_actors_, 1, __ATOMIC_SEQ_CST ); |
---|
312 | } |
---|
313 | static inline void ^?{}( actor & this ) {} |
---|
314 | |
---|
315 | static inline void check_actor( actor & this ) { |
---|
316 | if ( this.allocation_ != Nodelete ) { |
---|
317 | switch( this.allocation_ ) { |
---|
318 | case Delete: delete( &this ); break; |
---|
319 | case Destroy: |
---|
320 | CFA_DEBUG( this.ticket = MAX; ); // mark as terminated |
---|
321 | ^?{}(this); |
---|
322 | break; |
---|
323 | case Finished: |
---|
324 | CFA_DEBUG( this.ticket = MAX; ); // mark as terminated |
---|
325 | break; |
---|
326 | default: ; // stop warning |
---|
327 | } |
---|
328 | |
---|
329 | if ( unlikely( __atomic_add_fetch( &__num_actors_, -1, __ATOMIC_SEQ_CST ) == 0 ) ) { // all actors have terminated |
---|
330 | unpark( __actor_executor_thd ); |
---|
331 | } |
---|
332 | } |
---|
333 | } |
---|
334 | |
---|
335 | struct message { |
---|
336 | Allocation allocation_; // allocation action |
---|
337 | }; |
---|
338 | |
---|
339 | static inline void ?{}( message & this ) { this.allocation_ = Nodelete; } |
---|
340 | static inline void ?{}( message & this, Allocation allocation ) { this.allocation_ = allocation; } |
---|
341 | static inline void ^?{}( message & this ) {} |
---|
342 | |
---|
343 | static inline void check_message( message & this ) { |
---|
344 | switch ( this.allocation_ ) { // analyze message status |
---|
345 | case Nodelete: break; |
---|
346 | case Delete: delete( &this ); break; |
---|
347 | case Destroy: ^?{}(this); break; |
---|
348 | case Finished: break; |
---|
349 | } // switch |
---|
350 | } |
---|
351 | |
---|
352 | static inline void deliver_request( request & this ) { |
---|
353 | Allocation actor_allocation = this.fn( *this.receiver, *this.msg ); |
---|
354 | this.receiver->allocation_ = actor_allocation; |
---|
355 | check_actor( *this.receiver ); |
---|
356 | check_message( *this.msg ); |
---|
357 | } |
---|
358 | |
---|
359 | // Couple of ways to approach work stealing |
---|
360 | // 1: completely worker agnostic, just find a big queue and steal it |
---|
361 | // 2: track some heuristic of worker's load and focus on that and then pick a queue from that worker |
---|
362 | // worker heuristics: |
---|
363 | // - how many queues have work? |
---|
364 | // - size of largest queue |
---|
365 | // - total # of messages |
---|
366 | // - messages currently servicing |
---|
367 | // - pick randomly |
---|
368 | // - pick from closer threads/workers (this can be combined with others) |
---|
369 | |
---|
370 | // lock free or global lock for queue stealing |
---|
371 | #define __LOCK_SWP 0 |
---|
372 | |
---|
373 | __spinlock_t swp_lock; |
---|
374 | |
---|
375 | // tries to atomically swap two queues and returns a bool indicating if the swap failed |
---|
376 | static inline bool try_swap_queues( worker & this, unsigned int victim_idx, unsigned int my_idx ) with(this) { |
---|
377 | #if __LOCK_SWP |
---|
378 | |
---|
379 | lock( swp_lock __cfaabi_dbg_ctx2 ); |
---|
380 | work_queue * temp = request_queues[my_idx]; |
---|
381 | request_queues[my_idx] = request_queues[victim_idx]; |
---|
382 | request_queues[victim_idx] = temp; |
---|
383 | unlock( swp_lock ); |
---|
384 | |
---|
385 | return true; |
---|
386 | |
---|
387 | #else // __LOCK_SWP else |
---|
388 | work_queue * my_queue = request_queues[my_idx]; |
---|
389 | work_queue * other_queue = request_queues[victim_idx]; |
---|
390 | if ( other_queue == 0p || my_queue == 0p ) return false; |
---|
391 | |
---|
392 | // try to set our queue ptr to be 0p. If it fails someone moved our queue so return false |
---|
393 | if ( !__atomic_compare_exchange_n( &request_queues[my_idx], &my_queue, 0p, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST ) ) |
---|
394 | return false; |
---|
395 | |
---|
396 | // try to set other queue ptr to be our queue ptr. If it fails someone moved the other queue so fix up then return false |
---|
397 | if ( !__atomic_compare_exchange_n( &request_queues[victim_idx], &other_queue, my_queue, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST ) ) { |
---|
398 | /* paranoid */ verify( request_queues[my_idx] == 0p ); |
---|
399 | request_queues[my_idx] = my_queue; // reset my queue ptr back to appropriate val |
---|
400 | return false; |
---|
401 | } |
---|
402 | |
---|
403 | // we have successfully swapped and since our queue is 0p no one will touch it so write back new queue ptr non atomically |
---|
404 | request_queues[my_idx] = other_queue; // last write does not need to be atomic |
---|
405 | return true; |
---|
406 | |
---|
407 | #endif // __LOCK_SWP |
---|
408 | } |
---|
409 | |
---|
410 | // once a worker to steal from has been chosen, choose queue to steal from |
---|
411 | static inline bool choose_queue( worker & this, unsigned int victim_id, unsigned int & last_idx ) with(this) { |
---|
412 | #if __RAND_QUEUE |
---|
413 | unsigned int tries = 0; |
---|
414 | const unsigned int start_idx = prng( n_queues ); |
---|
415 | work_queue * curr_steal_queue; |
---|
416 | |
---|
417 | for ( unsigned int i = start_idx; tries < n_queues; i = (i + 1) % n_queues ) { |
---|
418 | tries++; |
---|
419 | curr_steal_queue = request_queues[i]; |
---|
420 | #if __STEAL_WORK |
---|
421 | |
---|
422 | // avoid empty queues and queues that are being operated on |
---|
423 | if ( curr_steal_queue->being_processed || isEmpty( *curr_steal_queue->c_queue ) ) |
---|
424 | continue; |
---|
425 | |
---|
426 | // in this case we just return from transfer if this doesn't work |
---|
427 | transfer( *curr_steal_queue, ¤t_queue, request_queues, i ); |
---|
428 | if ( isEmpty( *current_queue ) ) continue; |
---|
429 | last_idx = i; |
---|
430 | |
---|
431 | #ifdef __STEAL_STATS |
---|
432 | stolen++; |
---|
433 | #endif // __STEAL_STATS |
---|
434 | |
---|
435 | #else // __STEAL_WORK else |
---|
436 | |
---|
437 | // avoid empty queues and queues that are being operated on |
---|
438 | if ( curr_steal_queue == 0p || curr_steal_queue->being_processed || isEmpty( *curr_steal_queue->c_queue ) ) |
---|
439 | continue; |
---|
440 | |
---|
441 | #ifdef __STEAL_STATS |
---|
442 | bool success = try_swap_queues( this, i, last_idx ); |
---|
443 | if ( success ) stolen++; |
---|
444 | #else |
---|
445 | try_swap_queues( this, i, last_idx ); |
---|
446 | #endif // __STEAL_STATS |
---|
447 | |
---|
448 | // C_TODO: try transfer immediately |
---|
449 | // transfer( *request_queues[last_idx], ¤t_queue, request_queues, last_idx ); |
---|
450 | // if ( isEmpty( *current_queue ) ) return false; |
---|
451 | return false; |
---|
452 | |
---|
453 | #endif // __STEAL_WORK |
---|
454 | |
---|
455 | return true; |
---|
456 | } // for |
---|
457 | return false; |
---|
458 | |
---|
459 | #elif __RAND_WORKER |
---|
460 | |
---|
461 | // have to calculate victim start and range since victim may be deleted before us in shutdown |
---|
462 | const unsigned int queues_per_worker = n_queues / n_workers; |
---|
463 | const unsigned int extras = n_queues % n_workers; |
---|
464 | unsigned int vic_start, vic_range; |
---|
465 | if ( extras > victim_id ) { |
---|
466 | vic_range = queues_per_worker + 1; |
---|
467 | vic_start = vic_range * victim_id; |
---|
468 | } else { |
---|
469 | vic_start = extras + victim_id * queues_per_worker; |
---|
470 | vic_range = queues_per_worker; |
---|
471 | } |
---|
472 | unsigned int start_idx = prng( vic_range ); |
---|
473 | unsigned int tries = 0; |
---|
474 | work_queue * curr_steal_queue; |
---|
475 | |
---|
476 | for ( unsigned int i = start_idx; tries < vic_range; i = (i + 1) % vic_range ) { |
---|
477 | tries++; |
---|
478 | curr_steal_queue = request_queues[ i + vic_start ]; |
---|
479 | // avoid empty queues and queues that are being operated on |
---|
480 | if ( curr_steal_queue == 0p || curr_steal_queue->being_processed || isEmpty( *curr_steal_queue->c_queue ) ) |
---|
481 | continue; |
---|
482 | |
---|
483 | try_swap_queues( this, i, last_idx ); |
---|
484 | |
---|
485 | #ifdef __STEAL_STATS |
---|
486 | bool success = try_swap_queues( this, i, last_idx ); |
---|
487 | if ( success ) stolen++; |
---|
488 | #else |
---|
489 | try_swap_queues( this, i, last_idx ); |
---|
490 | #endif // __STEAL_STATS |
---|
491 | |
---|
492 | // C_TODO: try transfer immediately |
---|
493 | // transfer( *request_queues[last_idx], ¤t_queue, request_queues, last_idx ); |
---|
494 | // if ( isEmpty( *current_queue ) ) return false; |
---|
495 | return false; |
---|
496 | } |
---|
497 | #endif |
---|
498 | } |
---|
499 | |
---|
500 | // choose a worker to steal from |
---|
501 | static inline bool choose_victim( worker & this, unsigned int & last_idx ) with(this) { |
---|
502 | #if __RAND_WORKER |
---|
503 | unsigned int victim = prng( n_workers ); |
---|
504 | if ( victim == id ) victim = ( victim + 1 ) % n_workers; |
---|
505 | return choose_queue( this, victim, last_idx ); |
---|
506 | #else |
---|
507 | return choose_queue( this, 0, last_idx ); |
---|
508 | #endif |
---|
509 | } |
---|
510 | |
---|
511 | // look for work to steal |
---|
512 | // returns a bool: true => a queue was stolen, false => no work was stolen |
---|
513 | static inline bool steal_work( worker & this, unsigned int & last_idx ) with(this) { // C_TODO: add debug tracking of how many steals occur |
---|
514 | // to steal queue acquire both queue's locks in address ordering (maybe can do atomic swap) |
---|
515 | // maybe a flag to hint which queue is being processed |
---|
516 | // look at count to see if queue is worth stealing (dont steal empty queues) |
---|
517 | // if steal and then flag is up then dont process and just continue looking at own queues |
---|
518 | // (best effort approach) its ok if stealing isn't fruitful |
---|
519 | // -> more important to not delay busy threads |
---|
520 | |
---|
521 | return choose_victim( this, last_idx ); |
---|
522 | } |
---|
523 | |
---|
524 | void main( worker & this ) with(this) { |
---|
525 | // threshold of empty queues we see before we go stealing |
---|
526 | const unsigned int steal_threshold = 2 * n_queues; |
---|
527 | unsigned int curr_idx; |
---|
528 | work_queue * curr_work_queue; |
---|
529 | Exit: |
---|
530 | for ( unsigned int i = 0;; i = (i + 1) % range ) { // cycle through set of request buffers |
---|
531 | // C_TODO: potentially check queue count instead of immediately trying to transfer |
---|
532 | curr_idx = i + start; |
---|
533 | curr_work_queue = request_queues[curr_idx]; |
---|
534 | transfer( *curr_work_queue, ¤t_queue, request_queues, curr_idx ); |
---|
535 | if ( isEmpty( *current_queue ) ) { |
---|
536 | #if __STEAL |
---|
537 | empty_count++; |
---|
538 | if ( empty_count < steal_threshold ) continue; |
---|
539 | empty_count = 0; // C_TODO: look into stealing backoff schemes |
---|
540 | #ifdef __STEAL_STATS |
---|
541 | try_steal++; |
---|
542 | #endif // __STEAL_STATS |
---|
543 | |
---|
544 | if ( ! steal_work( this, curr_idx ) ) continue; |
---|
545 | |
---|
546 | #else // __STEAL else |
---|
547 | |
---|
548 | continue; |
---|
549 | |
---|
550 | #endif // __STEAL |
---|
551 | } |
---|
552 | while ( ! isEmpty( *current_queue ) ) { |
---|
553 | &req = &remove( *current_queue ); |
---|
554 | if ( !&req ) continue; // possibly add some work stealing/idle sleep here |
---|
555 | if ( req.stop ) break Exit; |
---|
556 | deliver_request( req ); |
---|
557 | } |
---|
558 | #if __STEAL |
---|
559 | curr_work_queue->being_processed = false; // set done processing |
---|
560 | #endif |
---|
561 | empty_count = 0; // we found work so reset empty counter |
---|
562 | reclaim( *current_queue ); |
---|
563 | } // for |
---|
564 | } |
---|
565 | |
---|
566 | static inline void send( executor & this, request & req, unsigned long int ticket ) with(this) { |
---|
567 | insert( request_queues[ticket], req); |
---|
568 | } |
---|
569 | |
---|
570 | static inline void send( actor & this, request & req ) { |
---|
571 | send( *__actor_executor_, req, this.ticket ); |
---|
572 | } |
---|
573 | |
---|
574 | static inline void start_actor_system( size_t num_thds ) { |
---|
575 | __actor_executor_thd = active_thread(); |
---|
576 | __actor_executor_ = alloc(); |
---|
577 | (*__actor_executor_){ 0, num_thds, num_thds == 1 ? 1 : num_thds * 16 }; |
---|
578 | } |
---|
579 | |
---|
580 | static inline void start_actor_system() { start_actor_system( active_cluster()->procs.total ); } |
---|
581 | |
---|
582 | static inline void start_actor_system( executor & this ) { |
---|
583 | __actor_executor_thd = active_thread(); |
---|
584 | __actor_executor_ = &this; |
---|
585 | __actor_executor_passed = true; |
---|
586 | } |
---|
587 | |
---|
588 | static inline void stop_actor_system() { |
---|
589 | park( ); // will receive signal when actor system is finished |
---|
590 | |
---|
591 | if ( !__actor_executor_passed ) delete( __actor_executor_ ); |
---|
592 | __actor_executor_ = 0p; |
---|
593 | __actor_executor_thd = 0p; |
---|
594 | __next_ticket = 0; |
---|
595 | __actor_executor_passed = false; |
---|
596 | } |
---|