source: libcfa/src/concurrency/ready_queue.cfa @ b2fc7ad9

arm-ehjacob/cs343-translationnew-ast-unique-expr
Last change on this file since b2fc7ad9 was b2fc7ad9, checked in by Thierry Delisle <tdelisle@…>, 7 months ago

Fixed missing return.
Was incorrectly removed in a33c11376e88fecef869e2f63e32b80f9410edc8

  • Property mode set to 100644
File size: 22.4 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2019 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// ready_queue.cfa --
8//
9// Author           : Thierry Delisle
10// Created On       : Mon Nov dd 16:29:18 2019
11// Last Modified By :
12// Last Modified On :
13// Update Count     :
14//
15
16#define __cforall_thread__
17// #define __CFA_DEBUG_PRINT_READY_QUEUE__
18
19// #define USE_MPSC
20
21#define USE_RELAXED_FIFO
22// #define USE_WORK_STEALING
23
24#include "bits/defs.hfa"
25#include "kernel_private.hfa"
26
27#define _GNU_SOURCE
28#include "stdlib.hfa"
29#include "math.hfa"
30
31#include <unistd.h>
32
33#include "ready_subqueue.hfa"
34
35static const size_t cache_line_size = 64;
36
37#if !defined(__CFA_NO_STATISTICS__)
38        #define __STATS(...) __VA_ARGS__
39#else
40        #define __STATS(...)
41#endif
42
43// No overriden function, no environment variable, no define
44// fall back to a magic number
45#ifndef __CFA_MAX_PROCESSORS__
46        #define __CFA_MAX_PROCESSORS__ 1024
47#endif
48
49#if   defined(USE_RELAXED_FIFO)
50        #define BIAS 4
51        #define READYQ_SHARD_FACTOR 4
52        #define SEQUENTIAL_SHARD 1
53#elif defined(USE_WORK_STEALING)
54        #define READYQ_SHARD_FACTOR 2
55        #define SEQUENTIAL_SHARD 2
56#else
57        #error no scheduling strategy selected
58#endif
59
60static inline struct $thread * try_pop(struct cluster * cltr, unsigned w __STATS(, __stats_readyQ_pop_t & stats));
61static inline struct $thread * try_pop(struct cluster * cltr, unsigned i, unsigned j __STATS(, __stats_readyQ_pop_t & stats));
62static inline struct $thread * search(struct cluster * cltr);
63static inline [unsigned, bool] idx_from_r(unsigned r, unsigned preferred);
64
65
66// returns the maximum number of processors the RWLock support
67__attribute__((weak)) unsigned __max_processors() {
68        const char * max_cores_s = getenv("CFA_MAX_PROCESSORS");
69        if(!max_cores_s) {
70                __cfadbg_print_nolock(ready_queue, "No CFA_MAX_PROCESSORS in ENV\n");
71                return __CFA_MAX_PROCESSORS__;
72        }
73
74        char * endptr = 0p;
75        long int max_cores_l = strtol(max_cores_s, &endptr, 10);
76        if(max_cores_l < 1 || max_cores_l > 65535) {
77                __cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS out of range : %ld\n", max_cores_l);
78                return __CFA_MAX_PROCESSORS__;
79        }
80        if('\0' != *endptr) {
81                __cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS not a decimal number : %s\n", max_cores_s);
82                return __CFA_MAX_PROCESSORS__;
83        }
84
85        return max_cores_l;
86}
87
88//=======================================================================
89// Cluster wide reader-writer lock
90//=======================================================================
91void  ?{}(__scheduler_RWLock_t & this) {
92        this.max   = __max_processors();
93        this.alloc = 0;
94        this.ready = 0;
95        this.lock  = false;
96        this.data  = alloc(this.max);
97
98        /*paranoid*/ verify( 0 == (((uintptr_t)(this.data    )) % 64) );
99        /*paranoid*/ verify( 0 == (((uintptr_t)(this.data + 1)) % 64) );
100        /*paranoid*/ verify(__atomic_is_lock_free(sizeof(this.alloc), &this.alloc));
101        /*paranoid*/ verify(__atomic_is_lock_free(sizeof(this.ready), &this.ready));
102
103}
104void ^?{}(__scheduler_RWLock_t & this) {
105        free(this.data);
106}
107
108void ?{}( __scheduler_lock_id_t & this, __processor_id_t * proc ) {
109        this.handle = proc;
110        this.lock   = false;
111        #ifdef __CFA_WITH_VERIFY__
112                this.owned  = false;
113        #endif
114}
115
116//=======================================================================
117// Lock-Free registering/unregistering of threads
118void register_proc_id( struct __processor_id_t * proc ) with(*__scheduler_lock) {
119        __cfadbg_print_safe(ready_queue, "Kernel : Registering proc %p for RW-Lock\n", proc);
120
121        // Step - 1 : check if there is already space in the data
122        uint_fast32_t s = ready;
123
124        // Check among all the ready
125        for(uint_fast32_t i = 0; i < s; i++) {
126                __processor_id_t * null = 0p; // Re-write every loop since compare thrashes it
127                if( __atomic_load_n(&data[i].handle, (int)__ATOMIC_RELAXED) == null
128                        && __atomic_compare_exchange_n( &data[i].handle, &null, proc, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
129                        /*paranoid*/ verify(i < ready);
130                        /*paranoid*/ verify(0 == (__alignof__(data[i]) % cache_line_size));
131                        /*paranoid*/ verify((((uintptr_t)&data[i]) % cache_line_size) == 0);
132                        proc->id = i;
133                        return;
134                }
135        }
136
137        if(max <= alloc) abort("Trying to create more than %ud processors", __scheduler_lock->max);
138
139        // Step - 2 : F&A to get a new spot in the array.
140        uint_fast32_t n = __atomic_fetch_add(&alloc, 1, __ATOMIC_SEQ_CST);
141        if(max <= n) abort("Trying to create more than %ud processors", __scheduler_lock->max);
142
143        // Step - 3 : Mark space as used and then publish it.
144        __scheduler_lock_id_t * storage = (__scheduler_lock_id_t *)&data[n];
145        (*storage){ proc };
146        while() {
147                unsigned copy = n;
148                if( __atomic_load_n(&ready, __ATOMIC_RELAXED) == n
149                        && __atomic_compare_exchange_n(&ready, &copy, n + 1, true, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST))
150                        break;
151                Pause();
152        }
153
154        __cfadbg_print_safe(ready_queue, "Kernel : Registering proc %p done, id %lu\n", proc, n);
155
156        // Return new spot.
157        /*paranoid*/ verify(n < ready);
158        /*paranoid*/ verify(__alignof__(data[n]) == (2 * cache_line_size));
159        /*paranoid*/ verify((((uintptr_t)&data[n]) % cache_line_size) == 0);
160        proc->id = n;
161}
162
163void unregister_proc_id( struct __processor_id_t * proc ) with(*__scheduler_lock) {
164        unsigned id = proc->id;
165        /*paranoid*/ verify(id < ready);
166        /*paranoid*/ verify(proc == __atomic_load_n(&data[id].handle, __ATOMIC_RELAXED));
167        __atomic_store_n(&data[id].handle, 0p, __ATOMIC_RELEASE);
168
169        __cfadbg_print_safe(ready_queue, "Kernel : Unregister proc %p\n", proc);
170}
171
172//-----------------------------------------------------------------------
173// Writer side : acquire when changing the ready queue, e.g. adding more
174//  queues or removing them.
175uint_fast32_t ready_mutate_lock( void ) with(*__scheduler_lock) {
176        /* paranoid */ verify( ! __preemption_enabled() );
177
178        // Step 1 : lock global lock
179        // It is needed to avoid processors that register mid Critical-Section
180        //   to simply lock their own lock and enter.
181        __atomic_acquire( &lock );
182
183        // Step 2 : lock per-proc lock
184        // Processors that are currently being registered aren't counted
185        //   but can't be in read_lock or in the critical section.
186        // All other processors are counted
187        uint_fast32_t s = ready;
188        for(uint_fast32_t i = 0; i < s; i++) {
189                __atomic_acquire( &data[i].lock );
190        }
191
192        /* paranoid */ verify( ! __preemption_enabled() );
193        return s;
194}
195
196void ready_mutate_unlock( uint_fast32_t last_s ) with(*__scheduler_lock) {
197        /* paranoid */ verify( ! __preemption_enabled() );
198
199        // Step 1 : release local locks
200        // This must be done while the global lock is held to avoid
201        //   threads that where created mid critical section
202        //   to race to lock their local locks and have the writer
203        //   immidiately unlock them
204        // Alternative solution : return s in write_lock and pass it to write_unlock
205        for(uint_fast32_t i = 0; i < last_s; i++) {
206                verify(data[i].lock);
207                __atomic_store_n(&data[i].lock, (bool)false, __ATOMIC_RELEASE);
208        }
209
210        // Step 2 : release global lock
211        /*paranoid*/ assert(true == lock);
212        __atomic_store_n(&lock, (bool)false, __ATOMIC_RELEASE);
213
214        /* paranoid */ verify( ! __preemption_enabled() );
215}
216
217//=======================================================================
218// Cforall Ready Queue used for scheduling
219//=======================================================================
220void ?{}(__ready_queue_t & this) with (this) {
221        lanes.data  = 0p;
222        lanes.tscs  = 0p;
223        lanes.count = 0;
224}
225
226void ^?{}(__ready_queue_t & this) with (this) {
227        verify( SEQUENTIAL_SHARD == lanes.count );
228        free(lanes.data);
229        free(lanes.tscs);
230}
231
232//-----------------------------------------------------------------------
233#if defined(USE_RELAXED_FIFO)
234        //-----------------------------------------------------------------------
235        // get index from random number with or without bias towards queues
236        static inline [unsigned, bool] idx_from_r(unsigned r, unsigned preferred) {
237                unsigned i;
238                bool local;
239                unsigned rlow  = r % BIAS;
240                unsigned rhigh = r / BIAS;
241                if((0 != rlow) && preferred >= 0) {
242                        // (BIAS - 1) out of BIAS chances
243                        // Use perferred queues
244                        i = preferred + (rhigh % READYQ_SHARD_FACTOR);
245                        local = true;
246                }
247                else {
248                        // 1 out of BIAS chances
249                        // Use all queues
250                        i = rhigh;
251                        local = false;
252                }
253                return [i, local];
254        }
255
256        __attribute__((hot)) void push(struct cluster * cltr, struct $thread * thrd) with (cltr->ready_queue) {
257                __cfadbg_print_safe(ready_queue, "Kernel : Pushing %p on cluster %p\n", thrd, cltr);
258
259                const bool external = (!kernelTLS().this_processor) || (cltr != kernelTLS().this_processor->cltr);
260                /* paranoid */ verify(external || kernelTLS().this_processor->rdq.id < lanes.count );
261
262                // write timestamp
263                thrd->link.ts = rdtscl();
264
265                bool local;
266                int preferred = external ? -1 : kernelTLS().this_processor->rdq.id;
267
268                // Try to pick a lane and lock it
269                unsigned i;
270                do {
271                        // Pick the index of a lane
272                        unsigned r = __tls_rand_fwd();
273                        [i, local] = idx_from_r(r, preferred);
274
275                        i %= __atomic_load_n( &lanes.count, __ATOMIC_RELAXED );
276
277                        #if !defined(__CFA_NO_STATISTICS__)
278                                if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.attempt, 1, __ATOMIC_RELAXED);
279                                else if(local) __tls_stats()->ready.push.local.attempt++;
280                                else __tls_stats()->ready.push.share.attempt++;
281                        #endif
282
283                #if defined(USE_MPSC)
284                        // mpsc always succeeds
285                } while( false );
286                #else
287                        // If we can't lock it retry
288                } while( !__atomic_try_acquire( &lanes.data[i].lock ) );
289                #endif
290
291                // Actually push it
292                push(lanes.data[i], thrd);
293
294                #if !defined(USE_MPSC)
295                        // Unlock and return
296                        __atomic_unlock( &lanes.data[i].lock );
297                #endif
298
299                // Mark the current index in the tls rng instance as having an item
300                __tls_rand_advance_bck();
301
302                __cfadbg_print_safe(ready_queue, "Kernel : Pushed %p on cluster %p (idx: %u, mask %llu, first %d)\n", thrd, cltr, i, used.mask[0], lane_first);
303
304                // Update statistics
305                #if !defined(__CFA_NO_STATISTICS__)
306                        if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.success, 1, __ATOMIC_RELAXED);
307                        else if(local) __tls_stats()->ready.push.local.success++;
308                        else __tls_stats()->ready.push.share.success++;
309                #endif
310        }
311
312        // Pop from the ready queue from a given cluster
313        __attribute__((hot)) $thread * pop_fast(struct cluster * cltr) with (cltr->ready_queue) {
314                /* paranoid */ verify( lanes.count > 0 );
315                /* paranoid */ verify( kernelTLS().this_processor );
316                /* paranoid */ verify( kernelTLS().this_processor->rdq.id < lanes.count );
317
318                unsigned count = __atomic_load_n( &lanes.count, __ATOMIC_RELAXED );
319                int preferred = kernelTLS().this_processor->rdq.id;
320
321
322                // As long as the list is not empty, try finding a lane that isn't empty and pop from it
323                for(25) {
324                        // Pick two lists at random
325                        unsigned ri = __tls_rand_bck();
326                        unsigned rj = __tls_rand_bck();
327
328                        unsigned i, j;
329                        __attribute__((unused)) bool locali, localj;
330                        [i, locali] = idx_from_r(ri, preferred);
331                        [j, localj] = idx_from_r(rj, preferred);
332
333                        i %= count;
334                        j %= count;
335
336                        // try popping from the 2 picked lists
337                        struct $thread * thrd = try_pop(cltr, i, j __STATS(, *(locali || localj ? &__tls_stats()->ready.pop.local : &__tls_stats()->ready.pop.help)));
338                        if(thrd) {
339                                return thrd;
340                        }
341                }
342
343                // All lanes where empty return 0p
344                return 0p;
345        }
346
347        __attribute__((hot)) struct $thread * pop_slow(struct cluster * cltr) { return pop_fast(cltr); }
348        __attribute__((hot)) struct $thread * pop_search(struct cluster * cltr) {
349                return search(cltr);
350        }
351#endif
352#if defined(USE_WORK_STEALING)
353        __attribute__((hot)) void push(struct cluster * cltr, struct $thread * thrd) with (cltr->ready_queue) {
354                __cfadbg_print_safe(ready_queue, "Kernel : Pushing %p on cluster %p\n", thrd, cltr);
355
356                const bool external = (!kernelTLS().this_processor) || (cltr != kernelTLS().this_processor->cltr);
357                /* paranoid */ verify(external || kernelTLS().this_processor->rdq.id < lanes.count );
358
359                // write timestamp
360                thrd->link.ts = rdtscl();
361
362                // Try to pick a lane and lock it
363                unsigned i;
364                do {
365                        #if !defined(__CFA_NO_STATISTICS__)
366                                if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.attempt, 1, __ATOMIC_RELAXED);
367                                else __tls_stats()->ready.push.local.attempt++;
368                        #endif
369
370                        if(unlikely(external)) {
371                                i = __tls_rand() % lanes.count;
372                        }
373                        else {
374                                processor * proc = kernelTLS().this_processor;
375                                unsigned r = proc->rdq.its++;
376                                i =  proc->rdq.id + (r % READYQ_SHARD_FACTOR);
377                        }
378
379
380                #if defined(USE_MPSC)
381                        // mpsc always succeeds
382                } while( false );
383                #else
384                        // If we can't lock it retry
385                } while( !__atomic_try_acquire( &lanes.data[i].lock ) );
386                #endif
387
388                // Actually push it
389                push(lanes.data[i], thrd);
390
391                #if !defined(USE_MPSC)
392                        // Unlock and return
393                        __atomic_unlock( &lanes.data[i].lock );
394                #endif
395
396                #if !defined(__CFA_NO_STATISTICS__)
397                        if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.success, 1, __ATOMIC_RELAXED);
398                        else __tls_stats()->ready.push.local.success++;
399                #endif
400
401                __cfadbg_print_safe(ready_queue, "Kernel : Pushed %p on cluster %p (idx: %u, mask %llu, first %d)\n", thrd, cltr, i, used.mask[0], lane_first);
402        }
403
404        // Pop from the ready queue from a given cluster
405        __attribute__((hot)) $thread * pop_fast(struct cluster * cltr) with (cltr->ready_queue) {
406                /* paranoid */ verify( lanes.count > 0 );
407                /* paranoid */ verify( kernelTLS().this_processor );
408                /* paranoid */ verify( kernelTLS().this_processor->rdq.id < lanes.count );
409
410                processor * proc = kernelTLS().this_processor;
411
412                if(proc->rdq.target == -1u) {
413                        proc->rdq.target = __tls_rand() % lanes.count;
414                        unsigned it1  = proc->rdq.itr;
415                        unsigned it2  = proc->rdq.itr + 1;
416                        unsigned idx1 = proc->rdq.id + (it1 % READYQ_SHARD_FACTOR);
417                        unsigned idx2 = proc->rdq.id + (it2 % READYQ_SHARD_FACTOR);
418                        unsigned long long tsc1 = ts(lanes.data[idx1]);
419                        unsigned long long tsc2 = ts(lanes.data[idx2]);
420                        proc->rdq.cutoff = min(tsc1, tsc2);
421                        if(proc->rdq.cutoff == 0) proc->rdq.cutoff = -1ull;
422                }
423                else {
424                        unsigned target = proc->rdq.target;
425                        proc->rdq.target = -1u;
426                        if(lanes.tscs[target].tv < proc->rdq.cutoff) {
427                                $thread * t = try_pop(cltr, target __STATS(, __tls_stats()->ready.pop.help));
428                                if(t) return t;
429                        }
430                }
431
432                for(READYQ_SHARD_FACTOR) {
433                        unsigned i = proc->rdq.id + (--proc->rdq.itr % READYQ_SHARD_FACTOR);
434                        if($thread * t = try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.local))) return t;
435                }
436                return 0p;
437        }
438
439        __attribute__((hot)) struct $thread * pop_slow(struct cluster * cltr) with (cltr->ready_queue) {
440                unsigned i = __tls_rand() % lanes.count;
441                return try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.steal));
442        }
443
444        __attribute__((hot)) struct $thread * pop_search(struct cluster * cltr) with (cltr->ready_queue) {
445                return search(cltr);
446        }
447#endif
448
449//=======================================================================
450// Various Ready Queue utilities
451//=======================================================================
452// these function work the same or almost the same
453// whether they are using work-stealing or relaxed fifo scheduling
454
455//-----------------------------------------------------------------------
456// try to pop from a lane given by index w
457static inline struct $thread * try_pop(struct cluster * cltr, unsigned w __STATS(, __stats_readyQ_pop_t & stats)) with (cltr->ready_queue) {
458        __STATS( stats.attempt++; )
459
460        // Get relevant elements locally
461        __intrusive_lane_t & lane = lanes.data[w];
462
463        // If list looks empty retry
464        if( is_empty(lane) ) {
465                __STATS( stats.espec++; )
466                return 0p;
467        }
468
469        // If we can't get the lock retry
470        if( !__atomic_try_acquire(&lane.lock) ) {
471                __STATS( stats.elock++; )
472                return 0p;
473        }
474
475        // If list is empty, unlock and retry
476        if( is_empty(lane) ) {
477                __atomic_unlock(&lane.lock);
478                __STATS( stats.eempty++; )
479                return 0p;
480        }
481
482        // Actually pop the list
483        struct $thread * thrd;
484        thrd = pop(lane);
485
486        /* paranoid */ verify(thrd);
487        /* paranoid */ verify(lane.lock);
488
489        // Unlock and return
490        __atomic_unlock(&lane.lock);
491
492        // Update statistics
493        __STATS( stats.success++; )
494
495        #if defined(USE_WORK_STEALING)
496                lanes.tscs[w].tv = thrd->link.ts;
497        #endif
498
499        // return the popped thread
500        return thrd;
501}
502
503//-----------------------------------------------------------------------
504// try to pop from any lanes making sure you don't miss any threads push
505// before the start of the function
506static inline struct $thread * search(struct cluster * cltr) with (cltr->ready_queue) {
507        /* paranoid */ verify( lanes.count > 0 );
508        unsigned count = __atomic_load_n( &lanes.count, __ATOMIC_RELAXED );
509        unsigned offset = __tls_rand();
510        for(i; count) {
511                unsigned idx = (offset + i) % count;
512                struct $thread * thrd = try_pop(cltr, idx __STATS(, __tls_stats()->ready.pop.search));
513                if(thrd) {
514                        return thrd;
515                }
516        }
517
518        // All lanes where empty return 0p
519        return 0p;
520}
521
522//-----------------------------------------------------------------------
523// Check that all the intrusive queues in the data structure are still consistent
524static void check( __ready_queue_t & q ) with (q) {
525        #if defined(__CFA_WITH_VERIFY__) && !defined(USE_MPSC)
526                {
527                        for( idx ; lanes.count ) {
528                                __intrusive_lane_t & sl = lanes.data[idx];
529                                assert(!lanes.data[idx].lock);
530
531                                assert(head(sl)->link.prev == 0p );
532                                assert(head(sl)->link.next->link.prev == head(sl) );
533                                assert(tail(sl)->link.next == 0p );
534                                assert(tail(sl)->link.prev->link.next == tail(sl) );
535
536                                if(is_empty(sl)) {
537                                        assert(tail(sl)->link.prev == head(sl));
538                                        assert(head(sl)->link.next == tail(sl));
539                                } else {
540                                        assert(tail(sl)->link.prev != head(sl));
541                                        assert(head(sl)->link.next != tail(sl));
542                                }
543                        }
544                }
545        #endif
546}
547
548//-----------------------------------------------------------------------
549// Given 2 indexes, pick the list with the oldest push an try to pop from it
550static inline struct $thread * try_pop(struct cluster * cltr, unsigned i, unsigned j __STATS(, __stats_readyQ_pop_t & stats)) with (cltr->ready_queue) {
551        // Pick the bet list
552        int w = i;
553        if( __builtin_expect(!is_empty(lanes.data[j]), true) ) {
554                w = (ts(lanes.data[i]) < ts(lanes.data[j])) ? i : j;
555        }
556
557        return try_pop(cltr, w __STATS(, stats));
558}
559
560// Call this function of the intrusive list was moved using memcpy
561// fixes the list so that the pointers back to anchors aren't left dangling
562static inline void fix(__intrusive_lane_t & ll) {
563        #if !defined(USE_MPSC)
564                // if the list is not empty then follow he pointer and fix its reverse
565                if(!is_empty(ll)) {
566                        head(ll)->link.next->link.prev = head(ll);
567                        tail(ll)->link.prev->link.next = tail(ll);
568                }
569                // Otherwise just reset the list
570                else {
571                        verify(tail(ll)->link.next == 0p);
572                        tail(ll)->link.prev = head(ll);
573                        head(ll)->link.next = tail(ll);
574                        verify(head(ll)->link.prev == 0p);
575                }
576        #endif
577}
578
579static void assign_list(unsigned & value, dlist(processor, processor) & list, unsigned count) {
580        processor * it = &list`first;
581        for(unsigned i = 0; i < count; i++) {
582                /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
583                it->rdq.id = value;
584                it->rdq.target = -1u;
585                value += READYQ_SHARD_FACTOR;
586                it = &(*it)`next;
587        }
588}
589
590static void reassign_cltr_id(struct cluster * cltr) {
591        unsigned preferred = 0;
592        assign_list(preferred, cltr->procs.actives, cltr->procs.total - cltr->procs.idle);
593        assign_list(preferred, cltr->procs.idles  , cltr->procs.idle );
594}
595
596static void fix_times( struct cluster * cltr ) with( cltr->ready_queue ) {
597        #if defined(USE_WORK_STEALING)
598                lanes.tscs = alloc(lanes.count, lanes.tscs`realloc);
599                for(i; lanes.count) {
600                        lanes.tscs[i].tv = ts(lanes.data[i]);
601                }
602        #endif
603}
604
605// Grow the ready queue
606void ready_queue_grow(struct cluster * cltr) {
607        size_t ncount;
608        int target = cltr->procs.total;
609
610        /* paranoid */ verify( ready_mutate_islocked() );
611        __cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue\n");
612
613        // Make sure that everything is consistent
614        /* paranoid */ check( cltr->ready_queue );
615
616        // grow the ready queue
617        with( cltr->ready_queue ) {
618                // Find new count
619                // Make sure we always have atleast 1 list
620                if(target >= 2) {
621                        ncount = target * READYQ_SHARD_FACTOR;
622                } else {
623                        ncount = SEQUENTIAL_SHARD;
624                }
625
626                // Allocate new array (uses realloc and memcpies the data)
627                lanes.data = alloc( ncount, lanes.data`realloc );
628
629                // Fix the moved data
630                for( idx; (size_t)lanes.count ) {
631                        fix(lanes.data[idx]);
632                }
633
634                // Construct new data
635                for( idx; (size_t)lanes.count ~ ncount) {
636                        (lanes.data[idx]){};
637                }
638
639                // Update original
640                lanes.count = ncount;
641        }
642
643        fix_times(cltr);
644
645        reassign_cltr_id(cltr);
646
647        // Make sure that everything is consistent
648        /* paranoid */ check( cltr->ready_queue );
649
650        __cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue done\n");
651
652        /* paranoid */ verify( ready_mutate_islocked() );
653}
654
655// Shrink the ready queue
656void ready_queue_shrink(struct cluster * cltr) {
657        /* paranoid */ verify( ready_mutate_islocked() );
658        __cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue\n");
659
660        // Make sure that everything is consistent
661        /* paranoid */ check( cltr->ready_queue );
662
663        int target = cltr->procs.total;
664
665        with( cltr->ready_queue ) {
666                // Remember old count
667                size_t ocount = lanes.count;
668
669                // Find new count
670                // Make sure we always have atleast 1 list
671                lanes.count = target >= 2 ? target * READYQ_SHARD_FACTOR: SEQUENTIAL_SHARD;
672                /* paranoid */ verify( ocount >= lanes.count );
673                /* paranoid */ verify( lanes.count == target * READYQ_SHARD_FACTOR || target < 2 );
674
675                // for printing count the number of displaced threads
676                #if defined(__CFA_DEBUG_PRINT__) || defined(__CFA_DEBUG_PRINT_READY_QUEUE__)
677                        __attribute__((unused)) size_t displaced = 0;
678                #endif
679
680                // redistribute old data
681                for( idx; (size_t)lanes.count ~ ocount) {
682                        // Lock is not strictly needed but makes checking invariants much easier
683                        __attribute__((unused)) bool locked = __atomic_try_acquire(&lanes.data[idx].lock);
684                        verify(locked);
685
686                        // As long as we can pop from this lane to push the threads somewhere else in the queue
687                        while(!is_empty(lanes.data[idx])) {
688                                struct $thread * thrd;
689                                thrd = pop(lanes.data[idx]);
690
691                                push(cltr, thrd);
692
693                                // for printing count the number of displaced threads
694                                #if defined(__CFA_DEBUG_PRINT__) || defined(__CFA_DEBUG_PRINT_READY_QUEUE__)
695                                        displaced++;
696                                #endif
697                        }
698
699                        // Unlock the lane
700                        __atomic_unlock(&lanes.data[idx].lock);
701
702                        // TODO print the queue statistics here
703
704                        ^(lanes.data[idx]){};
705                }
706
707                __cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue displaced %zu threads\n", displaced);
708
709                // Allocate new array (uses realloc and memcpies the data)
710                lanes.data = alloc( lanes.count, lanes.data`realloc );
711
712                // Fix the moved data
713                for( idx; (size_t)lanes.count ) {
714                        fix(lanes.data[idx]);
715                }
716        }
717
718        fix_times(cltr);
719
720        reassign_cltr_id(cltr);
721
722        // Make sure that everything is consistent
723        /* paranoid */ check( cltr->ready_queue );
724
725        __cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue done\n");
726        /* paranoid */ verify( ready_mutate_islocked() );
727}
Note: See TracBrowser for help on using the repository browser.