函数源码 |
Source File:kernel\padata.c |
Create Date:2022-07-27 15:08:58 |
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213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 | static void padata_reorder( struct parallel_data *pd) { struct padata_instance *pinst = pd->ps->pinst; int cb_cpu; struct padata_priv *padata; struct padata_serial_queue *squeue; struct padata_parallel_queue *next_queue; /* * We need to ensure that only one cpu can work on dequeueing of * the reorder queue the time. Calculating in which percpu reorder * queue the next object will arrive takes some time. A spinlock * would be highly contended. Also it is not clear in which order * the objects arrive to the reorder queues. So a cpu could wait to * get the lock just to notice that there is nothing to do at the * moment. Therefore we use a trylock and let the holder of the lock * care for all the objects enqueued during the holdtime of the lock. */ if (!spin_trylock_bh(&pd->lock)) return ; while (1) { padata = padata_find_next(pd, true ); /* * If the next object that needs serialization is parallel * processed by another cpu and is still on it's way to the * cpu's reorder queue, nothing to do for now. */ if (!padata) break ; cb_cpu = padata->cb_cpu; squeue = per_cpu_ptr(pd->squeue, cb_cpu); spin_lock(&squeue->serial.lock); list_add_tail(&padata->list, &squeue->serial.list); spin_unlock(&squeue->serial.lock); queue_work_on(cb_cpu, pinst->serial_wq, &squeue->work); } spin_unlock_bh(&pd->lock); /* * The next object that needs serialization might have arrived to * the reorder queues in the meantime. * * Ensure reorder queue is read after pd->lock is dropped so we see * new objects from another task in padata_do_serial. Pairs with * smp_mb__after_atomic in padata_do_serial. */ smp_mb(); next_queue = per_cpu_ptr(pd->pqueue, pd->cpu); if (!list_empty(&next_queue->reorder.list) && padata_find_next(pd, false )) queue_work(pinst->serial_wq, &pd->reorder_work); } |