runner.c 22.8 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
/*******************************************************************************
 * This file is part of GadgetSMP.
 * Coypright (c) 2012 Pedro Gonnet (pedro.gonnet@durham.ac.uk)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 ******************************************************************************/
Pedro Gonnet's avatar
Pedro Gonnet committed
19

Pedro Gonnet's avatar
Pedro Gonnet committed
20
21
/* Config parameters. */
#include "../config.h"
Pedro Gonnet's avatar
Pedro Gonnet committed
22
23
24
25
26
27
28
29
30
31

/* Some standard headers. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <math.h>
#include <float.h>
#include <limits.h>
#include <omp.h>
Pedro Gonnet's avatar
Pedro Gonnet committed
32
#include <sched.h>
Pedro Gonnet's avatar
Pedro Gonnet committed
33
34
35

/* Local headers. */
#include "cycle.h"
36
#include "const.h"
Pedro Gonnet's avatar
Pedro Gonnet committed
37
#include "lock.h"
38
39
40
#include "task.h"
#include "part.h"
#include "cell.h"
Pedro Gonnet's avatar
Pedro Gonnet committed
41
#include "space.h"
42
#include "queue.h"
Pedro Gonnet's avatar
Pedro Gonnet committed
43
#include "engine.h"
Pedro Gonnet's avatar
Pedro Gonnet committed
44
#include "runner.h"
45
#include "runner_iact.h"
Pedro Gonnet's avatar
Pedro Gonnet committed
46
47

/* Error macro. */
48
#define error(s) { fprintf( stderr , "%s:%s:%i: %s\n" , __FILE__ , __FUNCTION__ , __LINE__ , s ); abort(); }
Pedro Gonnet's avatar
Pedro Gonnet committed
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79

/* Convert cell location to ID. */
#define cell_getid( cdim , i , j , k ) ( (int)(k) + (cdim)[2]*( (int)(j) + (cdim)[1]*(int)(i) ) )

/* The timers. */
ticks runner_timer[ runner_timer_count ];

/* The counters. */
int runner_counter[ runner_counter_count ];

        

const float runner_shift[13*3] = {
     5.773502691896258e-01 ,  5.773502691896258e-01 ,  5.773502691896258e-01 ,
     7.071067811865475e-01 ,  7.071067811865475e-01 ,  0.0                   ,
     5.773502691896258e-01 ,  5.773502691896258e-01 , -5.773502691896258e-01 ,
     7.071067811865475e-01 ,  0.0                   ,  7.071067811865475e-01 ,
     1.0                   ,  0.0                   ,  0.0                   ,
     7.071067811865475e-01 ,  0.0                   , -7.071067811865475e-01 ,
     5.773502691896258e-01 , -5.773502691896258e-01 ,  5.773502691896258e-01 ,
     7.071067811865475e-01 , -7.071067811865475e-01 ,  0.0                   ,
     5.773502691896258e-01 , -5.773502691896258e-01 , -5.773502691896258e-01 ,
     0.0                   ,  7.071067811865475e-01 ,  7.071067811865475e-01 ,
     0.0                   ,  1.0                   ,  0.0                   ,
     0.0                   ,  7.071067811865475e-01 , -7.071067811865475e-01 ,
     0.0                   ,  0.0                   ,  1.0                   ,
    };
const char runner_flip[27] = { 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 0 ,
                               0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 }; 


80
81
82
83
84
85
86
87
88
/* Import the density functions. */
#define FUNCTION density
#include "runner_doiact.h"

#undef FUNCTION
#define FUNCTION force
#include "runner_doiact.h"


Pedro Gonnet's avatar
Pedro Gonnet committed
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
/**
 * @brief Sort the entries in ascending order using QuickSort.
 *
 * @param sort The entries
 * @param N The number of entries.
 */
 
void runner_dosort_ascending ( struct entry *sort , int N ) {

    struct {
        short int lo, hi;
        } qstack[10];
    int qpos, i, j, lo, hi, imin;
    struct entry temp;
    float pivot;
        
    /* Sort parts in cell_i in decreasing order with quicksort */
    qstack[0].lo = 0; qstack[0].hi = N - 1; qpos = 0;
    while ( qpos >= 0 ) {
        lo = qstack[qpos].lo; hi = qstack[qpos].hi;
        qpos -= 1;
        if ( hi - lo < 15 ) {
            for ( i = lo ; i < hi ; i++ ) {
                imin = i;
                for ( j = i+1 ; j <= hi ; j++ )
                    if ( sort[j].d < sort[imin].d )
                        imin = j;
                if ( imin != i ) {
                    temp = sort[imin]; sort[imin] = sort[i]; sort[i] = temp;
                    }
                }
            }
        else {
            pivot = sort[ ( lo + hi ) / 2 ].d;
            i = lo; j = hi;
            while ( i <= j ) {
                while ( sort[i].d < pivot ) i++;
                while ( sort[j].d > pivot ) j--;
                if ( i <= j ) {
                    if ( i < j ) {
                        temp = sort[i]; sort[i] = sort[j]; sort[j] = temp;
                        }
                    i += 1; j -= 1;
                    }
                }
            if ( j > ( lo + hi ) / 2 ) {
                if ( lo < j ) {
                    qpos += 1;
                    qstack[qpos].lo = lo;
                    qstack[qpos].hi = j;
                    }
                if ( i < hi ) {
                    qpos += 1;
                    qstack[qpos].lo = i;
                    qstack[qpos].hi = hi;
                    }
                }
            else {
                if ( i < hi ) {
                    qpos += 1;
                    qstack[qpos].lo = i;
                    qstack[qpos].hi = hi;
                    }
                if ( lo < j ) {
                    qpos += 1;
                    qstack[qpos].lo = lo;
                    qstack[qpos].hi = j;
                    }
                }
            }
        }
                
    }
    
    
/**
 * @brief Sort the particles in the given cell along all cardinal directions.
 *
 * @param r The #runner.
 * @param c The #cell.
 */
 
Pedro Gonnet's avatar
Pedro Gonnet committed
171
void runner_dosort ( struct runner *r , struct cell *c , int flags ) {
Pedro Gonnet's avatar
Pedro Gonnet committed
172
173
174

    struct entry *finger;
    struct entry *fingers[8];
175
    struct cpart *cparts = c->cparts;
Pedro Gonnet's avatar
Pedro Gonnet committed
176
177
    int j, k, count = c->count;
    int i, ind, off[8], inds[8], temp_i;
178
    // float shift[3];
Pedro Gonnet's avatar
Pedro Gonnet committed
179
    float buff[8], px[3];
Pedro Gonnet's avatar
Pedro Gonnet committed
180
181
182
183
184
185
    TIMER_TIC
    
    /* start by allocating the entry arrays. */
    if ( lock_lock( &c->lock ) != 0 )
        error( "Failed to lock cell." );
    if ( c->sort == NULL )
186
        if ( ( c->sort = (struct entry *)malloc( sizeof(struct entry) * (c->count + 1) * 14 ) ) == NULL )
Pedro Gonnet's avatar
Pedro Gonnet committed
187
188
189
190
191
192
193
            error( "Failed to allocate sort memory." );
    if ( lock_unlock( &c->lock ) != 0 )
        error( "Failed to unlock cell." );
        
    /* Does this cell have any progeny? */
    if ( c->split ) {
    
194
195
        /* Loop over the 13+1 different sort arrays. */
        for ( j = 0 ; j < 14 ; j++ ) {
Pedro Gonnet's avatar
Pedro Gonnet committed
196
197
198
199
200
        
            /* Has this sort array been flagged? */
            if ( !( flags & (1 << j) ) )
                continue;
                
201
202
203
204
205
            /* Sort any un-sorted progeny. */
            for ( k = 0 ; k < 8 ; k++ )
                if ( c->progeny[k] != NULL && ( c->progeny[k]->sorts[0] == NULL || !(c->progeny[k]->sorts[0]->flags & (1 << j)) ) )
                    runner_dosort( r , c->progeny[k] , 1 << j );
        
206
207
208
209
210
211
212
213
214
215
216
217
218
219
            /* Init the particle index offsets. */
            for ( off[0] = 0 , k = 1 ; k < 8 ; k++ )
                if ( c->progeny[k-1] != NULL )
                    off[k] = off[k-1] + c->progeny[k-1]->count;
                else
                    off[k] = off[k-1];

            /* Init the entries and indices. */
            for ( k = 0 ; k < 8 ; k++ ) {
                inds[k] = k;
                if ( c->progeny[k] != NULL && c->progeny[k]->count > 0 ) {
                    fingers[k] = &c->progeny[k]->sort[ j*(c->progeny[k]->count + 1) ];
                    buff[k] = fingers[k]->d;
                    off[k] = off[k];
Pedro Gonnet's avatar
Pedro Gonnet committed
220
                    }
221
222
                else
                    buff[k] = FLT_MAX;
Pedro Gonnet's avatar
Pedro Gonnet committed
223
224
                }

225
226
227
228
229
230
            /* Sort the buffer. */
            for ( i = 0 ; i < 7 ; i++ )
                for ( k = i+1 ; k < 8 ; k++ )
                    if ( buff[ inds[k] ] < buff[ inds[i] ] ) {
                        temp_i = inds[i]; inds[i] = inds[k]; inds[k] = temp_i;
                        }
Pedro Gonnet's avatar
Pedro Gonnet committed
231

232
233
234
            /* For each entry in the new sort list. */
            finger = &c->sort[ j*(count + 1) ];
            for ( ind = 0 ; ind < count ; ind++ ) {
Pedro Gonnet's avatar
Pedro Gonnet committed
235

236
237
238
                /* Copy the minimum into the new sort array. */
                finger[ind].d = buff[inds[0]];
                finger[ind].i = fingers[inds[0]]->i + off[inds[0]];
Pedro Gonnet's avatar
Pedro Gonnet committed
239

240
241
242
                /* Update the buffer. */
                fingers[inds[0]] += 1;
                buff[inds[0]] = fingers[inds[0]]->d;
Pedro Gonnet's avatar
Pedro Gonnet committed
243

244
245
246
247
                /* Find the smallest entry. */
                for ( k = 1 ; k < 8 && buff[inds[k]] < buff[inds[k-1]] ; k++ ) {
                    temp_i = inds[k-1]; inds[k-1] = inds[k]; inds[k] = temp_i;
                    }
Pedro Gonnet's avatar
Pedro Gonnet committed
248

249
                } /* Merge. */
Pedro Gonnet's avatar
Pedro Gonnet committed
250
251
252
253
254
255
256
257
258
259
260
261
            
            /* Add a sentinel. */
            c->sort[ j*(c->count + 1) + c->count ].d = FLT_MAX;
            c->sort[ j*(c->count + 1) + c->count ].i = 0;
            
            } /* loop over sort arrays. */
    
        } /* progeny? */
        
    /* Otherwise, just sort. */
    else {
    
262
        /* Fill the sort array. */
Pedro Gonnet's avatar
Pedro Gonnet committed
263
        for ( k = 0 ; k < count ; k++ ) {
264
265
266
            px[0] = cparts[k].x[0];
            px[1] = cparts[k].x[1];
            px[2] = cparts[k].x[2];
267
268
269
            for ( j = 0 ; j < 13 ; j++ )
                if ( flags & (1 << j) ) {
                    c->sort[ j*(count + 1) + k].i = k;
Pedro Gonnet's avatar
Pedro Gonnet committed
270
                    c->sort[ j*(count + 1) + k].d = px[0]*runner_shift[ 3*j + 0 ] + px[1]*runner_shift[ 3*j + 1 ] + px[2]*runner_shift[ 3*j + 2 ];
271
                    }
272
273
            if ( flags & (1 << 14) ) {
                c->sort[ 14*(count + 1) + k ].i = k;
274
                c->sort[ 14*(count + 1) + k ].d = cparts[k].dt;
275
                }
Pedro Gonnet's avatar
Pedro Gonnet committed
276
            }
277
278

        /* Add the sentinel and sort. */
279
        for ( j = 0 ; j < 14 ; j++ )
280
281
282
283
            if ( flags & (1 << j) ) {
                c->sort[ j*(count + 1) + c->count ].d = FLT_MAX;
                c->sort[ j*(count + 1) + c->count ].i = 0;
                runner_dosort_ascending( &c->sort[ j*(count + 1) ] , c->count );
Pedro Gonnet's avatar
Pedro Gonnet committed
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
                }
            
        }
        
    /* Verify the sorting. */
    /* for ( j = 0 ; j < 13 ; j++ ) {
        if ( !( flags & (1 << j) ) )
            continue;
        finger = &c->sort[ j*(c->count + 1) ];
        for ( k = 1 ; k < c->count ; k++ ) {
            if ( finger[k].d < finger[k-1].d )
                error( "Sorting failed, ascending array." );
            if ( finger[k].i >= c->count )
                error( "Sorting failed, indices borked." );
            }
        } */
300
        
Pedro Gonnet's avatar
Pedro Gonnet committed
301
302
    #ifdef TIMER_VERBOSE
        printf( "runner_dosort[%02i]: %i parts at depth %i (flags = %i%i%i%i%i%i%i%i%i%i%i%i%i) took %.3f ms.\n" ,
Pedro Gonnet's avatar
Pedro Gonnet committed
303
            r->id , c->count , c->depth ,
Pedro Gonnet's avatar
Pedro Gonnet committed
304
305
306
307
308
309
310
            (flags & 0x1000) >> 12 , (flags & 0x800) >> 11 , (flags & 0x400) >> 10 , (flags & 0x200) >> 9 , (flags & 0x100) >> 8 , (flags & 0x80) >> 7 , (flags & 0x40) >> 6 , (flags & 0x20) >> 5 , (flags & 0x10) >> 4 , (flags & 0x8) >> 3 , (flags & 0x4) >> 2 , (flags & 0x2) >> 1 , (flags & 0x1) >> 0 , 
            ((double)TIMER_TOC(runner_timer_dosort)) / CPU_TPS * 1000 ); fflush(stdout);
    #else
        TIMER_TOC(runner_timer_dosort);
    #endif

    }
311
312
313
314
315
    
    
/**
 * @brief Intermediate task between density and force
 *
Pedro Gonnet's avatar
Pedro Gonnet committed
316
 * @param r The runner thread.
317
318
319
 * @param ci THe cell.
 */
 
Pedro Gonnet's avatar
Pedro Gonnet committed
320
void runner_doghost ( struct runner *r , struct cell *c ) {
321
322

    struct part *p;
323
    struct cell *finger;
Pedro Gonnet's avatar
Pedro Gonnet committed
324
325
326
    int i, k, redo, count = c->count;
    int *pid;
    float ihg, ihg2;
327
    float dt_max = r->e->dt_max;
328
329
    TIMER_TIC
    
Pedro Gonnet's avatar
Pedro Gonnet committed
330
331
332
333
334
335
336
    /* Recurse? */
    if ( c->split ) {
        for ( k = 0 ; k < 8 ; k++ )
            if ( c->progeny[k] != NULL )
                runner_doghost( r , c->progeny[k] );
        return;
        }
337
        
Pedro Gonnet's avatar
Pedro Gonnet committed
338
339
340
341
342
343
344
345
    /* Init the IDs that have to be updated. */
    if ( ( pid = (int *)alloca( sizeof(int) * count ) ) == NULL )
        error( "Call to alloca failed." );
    for ( k = 0 ; k < count ; k++ )
        pid[k] = k;
        
    /* While there are particles that need to be updated... */
    while ( count > 0 ) {
346
    
Pedro Gonnet's avatar
Pedro Gonnet committed
347
348
        /* Reset the redo-count. */
        redo = 0;
349
    
Pedro Gonnet's avatar
Pedro Gonnet committed
350
351
352
353
354
        /* Loop over the parts in this cell. */
        for ( i = 0 ; i < count ; i++ ) {

            /* Get a direct pointer on the part. */
            p = &c->parts[ pid[i] ];
355
            
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
            /* Is this part within the timestep? */
            if ( p->dt <= dt_max ) {

                /* Adjust the computed rho. */
                ihg = kernel_igamma / p->h;
                ihg2 = ihg * ihg;
                p->rho *= ihg * ihg2;
                p->rho_dh *= ihg2 * ihg2;

                /* Update the smoothing length. */
                p->h -= ( p->wcount + kernel_root - const_nwneigh ) / p->wcount_dh;

                /* Did we get the right number density? */
                if ( p->wcount + kernel_root > const_nwneigh + 1 ||
                     p->wcount + kernel_root < const_nwneigh - 1 ) {
                    // printf( "runner_doghost: particle %lli (h=%e,depth=%i) has bad wcount=%f.\n" , p->id , p->h , c->depth , p->wcount + kernel_root ); fflush(stdout);
                    // p->h += ( p->wcount + kernel_root - const_nwneigh ) / p->wcount_dh;
                    pid[redo] = pid[i];
                    redo += 1;
                    p->wcount = 0.0;
                    p->wcount_dh = 0.0;
                    p->rho = 0.0;
                    p->rho_dh = 0.0;
                    continue;
                    }
                    
                /* Compute this particle's time step. */
                p->dt = const_cfl * p->h / sqrtf( const_gamma * ( const_gamma - 1.0f ) * p->u );

                /* Compute the pressure. */
                // p->P = p->rho * p->u * ( const_gamma - 1.0f );

                /* Compute the P/Omega/rho2. */
                p->POrho2 = p->u * ( const_gamma - 1.0f ) / ( p->rho + p->h * p->rho_dh / 3.0f );

Pedro Gonnet's avatar
Pedro Gonnet committed
391
392
393
394
395
396
397
398
399
400
401
                }

            /* Reset the acceleration. */
            for ( k = 0 ; k < 3 ; k++ )
                p->a[k] = 0.0f;

            /* Reset the time derivatives. */
            p->u_dt = 0.0f;
            p->h_dt = 0.0f;

            }
402
            
Pedro Gonnet's avatar
Pedro Gonnet committed
403
404
        /* Re-set the counter for the next loop (potentially). */
        count = redo;
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
        if ( count > 0 ) {
        
            // error( "Bad smoothing length, fixing this isn't implemented yet." );
            
            /* Climb up the cell hierarchy. */
            for ( finger = c ; finger != NULL ; finger = finger->parent ) {
            
                /* Run through this cell's density interactions. */
                for ( k = 0 ; k < finger->nr_density ; k++ ) {
                
                    /* Self-interaction? */
                    if ( finger->density[k]->type == task_type_self )
                        runner_doself_subset_density( r , finger , c->parts , pid , count );
                        
                    /* Otherwise, pair interaction? */
                    else if ( finger->density[k]->type == task_type_pair ) {
                    
                        /* Left or right? */
                        if ( finger->density[k]->ci == finger )
                            runner_dopair_subset_density( r , finger , c->parts , pid , count , finger->density[k]->cj );
                        else
                            runner_dopair_subset_density( r , finger , c->parts , pid , count , finger->density[k]->ci );
                        
                        }
                
                    /* Otherwise, sub interaction? */
431
432
433
434
435
436
437
438
439
                    else if ( finger->density[k]->type == task_type_sub ) {
                    
                        /* Left or right? */
                        if ( finger->density[k]->ci == finger )
                            runner_dosub_subset_density( r , finger , c->parts , pid , count , finger->density[k]->cj , -1 );
                        else
                            runner_dosub_subset_density( r , finger , c->parts , pid , count , finger->density[k]->ci , -1 );
                        
                        }
440
441
                
                    }
Pedro Gonnet's avatar
Pedro Gonnet committed
442
                    
443
444
445
                }
        
            }
446
447
448
449
450
            
        }

    #ifdef TIMER_VERBOSE
        printf( "runner_doghost[%02i]: %i parts at depth %i took %.3f ms.\n" ,
Pedro Gonnet's avatar
Pedro Gonnet committed
451
            r->id , c->count , c->depth ,
452
453
454
455
456
457
            ((double)TIMER_TOC(runner_timer_doghost)) / CPU_TPS * 1000 ); fflush(stdout);
    #else
        TIMER_TOC(runner_timer_doghost);
    #endif
    
    }
Pedro Gonnet's avatar
Pedro Gonnet committed
458
459
460
461
462
463
464
465
466
467


/**
 * @brief The #runner main thread routine.
 *
 * @param data A pointer to this thread's data.
 */
 
void *runner_main ( void *data ) {

Pedro Gonnet's avatar
Pedro Gonnet committed
468
469
470
    struct runner *r = (struct runner *)data;
    struct engine *e = r->e;
    int threadID = r->id;
Pedro Gonnet's avatar
Pedro Gonnet committed
471
    int k, qid, naq, keep, tpq;
Pedro Gonnet's avatar
Pedro Gonnet committed
472
    struct queue *queues[ e->nr_queues ], *myq;
Pedro Gonnet's avatar
Pedro Gonnet committed
473
474
    struct task *t;
    struct cell *ci, *cj;
Pedro Gonnet's avatar
Pedro Gonnet committed
475
    unsigned int myseed = rand() + r->id;
Pedro Gonnet's avatar
Pedro Gonnet committed
476
477
478
479
480
481
482
483
    #ifdef TIMER
        ticks stalled;
    #endif
    
    /* Main loop. */
    while ( 1 ) {
    
        /* Wait at the barrier. */
Pedro Gonnet's avatar
Pedro Gonnet committed
484
        engine_barrier( e );
Pedro Gonnet's avatar
Pedro Gonnet committed
485
486
        
        /* Set some convenient local data. */
Pedro Gonnet's avatar
Pedro Gonnet committed
487
        keep = e->policy & engine_policy_keep;
Pedro Gonnet's avatar
Pedro Gonnet committed
488
        myq = &e->queues[ threadID * e->nr_queues / e->nr_threads ];
Pedro Gonnet's avatar
Pedro Gonnet committed
489
        tpq = ceil( ((double)e->nr_threads) / e->nr_queues );
490
491
492
        #ifdef TIMER
            stalled = 0;
        #endif
Pedro Gonnet's avatar
Pedro Gonnet committed
493
494
        
        /* Set up the local list of active queues. */
Pedro Gonnet's avatar
Pedro Gonnet committed
495
        naq = e->nr_queues;
Pedro Gonnet's avatar
Pedro Gonnet committed
496
        for ( k = 0 ; k < naq ; k++ )
Pedro Gonnet's avatar
Pedro Gonnet committed
497
            queues[k] = &e->queues[k];
Pedro Gonnet's avatar
Pedro Gonnet committed
498
499
    
        /* Set up the local list of active queues. */
Pedro Gonnet's avatar
Pedro Gonnet committed
500
        naq = e->nr_queues;
Pedro Gonnet's avatar
Pedro Gonnet committed
501
        for ( k = 0 ; k < naq ; k++ )
Pedro Gonnet's avatar
Pedro Gonnet committed
502
            queues[k] = &e->queues[k];
Pedro Gonnet's avatar
Pedro Gonnet committed
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
    
        /* Loop while there are tasks... */
        while ( 1 ) {
        
            /* Remove any inactive queues. */
            for ( k = 0 ; k < naq ; k++ )
                if ( queues[k]->next == queues[k]->count ) {
                    naq -= 1;
                    queues[k] = queues[naq];
                    k -= 1;
                    }
            if ( naq == 0 )
                break;
        
            /* Get a task, how and from where depends on the policy. */
            TIMER_TIC
            t = NULL;
Pedro Gonnet's avatar
Pedro Gonnet committed
520
            if ( e->nr_queues == 1 ) {
521
                t = queue_gettask_old( &e->queues[0] , 1 , 0 );
Pedro Gonnet's avatar
Pedro Gonnet committed
522
                }
Pedro Gonnet's avatar
Pedro Gonnet committed
523
            else if ( e->policy & engine_policy_steal ) {
Pedro Gonnet's avatar
Pedro Gonnet committed
524
                if ( ( myq->next == myq->count ) ||
525
                     ( t = queue_gettask( myq , r->id , 0 , 0 ) ) == NULL ) {
Pedro Gonnet's avatar
Pedro Gonnet committed
526
                    TIMER_TIC2
527
                    qid = rand_r( &myseed ) % naq;
Pedro Gonnet's avatar
Pedro Gonnet committed
528
                    keep = ( e->policy & engine_policy_keep ) &&
Pedro Gonnet's avatar
Pedro Gonnet committed
529
530
531
532
533
                           ( myq->count <= myq->size-tpq );
                    if ( myq->next == myq->count )
                        COUNT(runner_counter_steal_empty);
                    else
                        COUNT(runner_counter_steal_stall);
534
                    t = queue_gettask( queues[qid] , r->id , 0 , keep );
Pedro Gonnet's avatar
Pedro Gonnet committed
535
536
                    if ( t != NULL && keep )
                        queue_insert( myq , t );
Pedro Gonnet's avatar
Pedro Gonnet committed
537
538
539
                    TIMER_TOC2(runner_timer_steal);
                    }
                }
Pedro Gonnet's avatar
Pedro Gonnet committed
540
            else if ( e->policy & engine_policy_rand ) {
541
                qid = rand_r( &myseed ) % naq;
542
                t = queue_gettask( queues[qid] , r->id , e->policy & engine_policy_block , 0 );
Pedro Gonnet's avatar
Pedro Gonnet committed
543
544
                }
            else {
545
                t = queue_gettask( &e->queues[threadID] , r->id , e->policy & engine_policy_block , 0 );
Pedro Gonnet's avatar
Pedro Gonnet committed
546
547
548
549
550
551
                }
            TIMER_TOC(runner_timer_getpair);
            
            /* Did I get anything? */
            if ( t == NULL ) {
                COUNT(runner_counter_stall);
552
553
554
555
                #ifdef TIMER
                    if ( !stalled )
                        stalled = getticks();
                #endif
Pedro Gonnet's avatar
Pedro Gonnet committed
556
557
558
559
560
561
562
                continue;
                }
            #ifdef TIMER
            else if ( stalled ) {
                stalled = getticks() - stalled;
                __sync_add_and_fetch( &runner_timer[runner_timer_stalled] , stalled );
                #ifdef TIMER_VERBOSE
Pedro Gonnet's avatar
Pedro Gonnet committed
563
                    printf( "runner_main[%02i]: stalled %.3f ms\n" , r->id , ((double)stalled) / CPU_TPS * 1000 );
Pedro Gonnet's avatar
Pedro Gonnet committed
564
565
566
567
568
569
570
571
572
573
574
575
                    fflush(stdout);
                #endif
                stalled = 0;
                }
            #endif
        
            /* Get the cells. */
            ci = t->ci;
            cj = t->cj;
            
            /* Different types of tasks... */
            switch ( t->type ) {
576
577
                case task_type_self:
                    if ( t->subtype == task_subtype_density )
578
                        runner_doself1_density( r , ci );
579
                    else if ( t->subtype == task_subtype_force )
580
                        runner_doself2_force( r , ci );
581
582
                    else
                        error( "Unknown task subtype." );
Pedro Gonnet's avatar
Pedro Gonnet committed
583
584
                    cell_unlocktree( ci );
                    break;
585
586
                case task_type_pair:
                    if ( t->subtype == task_subtype_density )
587
                        runner_dopair1_density( r , ci , cj );
588
                    else if ( t->subtype == task_subtype_force )
589
                        runner_dopair2_force( r , ci , cj );
590
591
                    else
                        error( "Unknown task subtype." );
Pedro Gonnet's avatar
Pedro Gonnet committed
592
593
594
                    cell_unlocktree( ci );
                    cell_unlocktree( cj );
                    break;
595
                case task_type_sort:
Pedro Gonnet's avatar
Pedro Gonnet committed
596
                    runner_dosort( r , ci , t->flags );
Pedro Gonnet's avatar
Pedro Gonnet committed
597
                    break;
598
599
                case task_type_sub:
                    if ( t->subtype == task_subtype_density )
600
                        runner_dosub1_density( r , ci , cj , t->flags );
601
                    else if ( t->subtype == task_subtype_force )
602
                        runner_dosub2_force( r , ci , cj , t->flags );
603
604
                    else
                        error( "Unknown task subtype." );
Pedro Gonnet's avatar
Pedro Gonnet committed
605
606
607
608
                    cell_unlocktree( ci );
                    if ( cj != NULL )
                        cell_unlocktree( cj );
                    break;
609
                case task_type_ghost:
Pedro Gonnet's avatar
Pedro Gonnet committed
610
                    if ( ci->super == ci )
Pedro Gonnet's avatar
Pedro Gonnet committed
611
                        runner_doghost( r , ci );
612
                    break;
Pedro Gonnet's avatar
Pedro Gonnet committed
613
614
615
616
617
618
                default:
                    error( "Unknown task type." );
                }
                
            /* Resolve any dependencies. */
            for ( k = 0 ; k < t->nr_unlock_tasks ; k++ )
Pedro Gonnet's avatar
Pedro Gonnet committed
619
620
                if ( __sync_fetch_and_sub( &t->unlock_tasks[k]->wait , 1 ) == 0 )
                    abort();
Pedro Gonnet's avatar
Pedro Gonnet committed
621
622
623
624
625
626
627
628
629
630
631
            for ( k = 0 ; k < t->nr_unlock_cells ; k++ )
                __sync_fetch_and_sub( &t->unlock_cells[k]->wait , 1 );
        
            } /* main loop. */
            
    	/* Any leftover stalls? */    
        #ifdef TIMER
        if ( stalled ) {
            stalled = getticks() - stalled;
            __sync_add_and_fetch( &runner_timer[runner_timer_stalled] , stalled );
            #ifdef TIMER_VERBOSE
Pedro Gonnet's avatar
Pedro Gonnet committed
632
                printf( "runner_main[%02i]: stalled %.3f ms\n" , r->id , ((double)stalled) / CPU_TPS * 1000 );
Pedro Gonnet's avatar
Pedro Gonnet committed
633
634
635
636
637
638
639
640
641
642
643
644
645
646
                fflush(stdout);
            #endif
            stalled = 0;
            }
        #endif
            
        }
        
    /* Be kind, rewind. */
    return NULL;

    }