2624 // If it didn't work, give up.
2625 if (fl->count() == 0) return NULL;
2626 }
2627 res = fl->get_chunk_at_head();
2628 assert(res != NULL, "Why was count non-zero?");
2629 }
2630 res->markNotFree();
2631 assert(!res->is_free(), "shouldn't be marked free");
2632 assert(oop(res)->klass_or_null() == NULL, "should look uninitialized");
2633 // mangle a just allocated object with a distinct pattern.
2634 debug_only(res->mangleAllocated(word_sz));
2635 return (HeapWord*)res;
2636 }
2637
2638 // Get a chunk of blocks of the right size and update related
2639 // book-keeping stats
2640 void CFLS_LAB::get_from_global_pool(size_t word_sz, AdaptiveFreeList<FreeChunk>* fl) {
2641 // Get the #blocks we want to claim
2642 size_t n_blks = (size_t)_blocks_to_claim[word_sz].average();
2643 assert(n_blks > 0, "Error");
2644 assert(ResizePLAB || n_blks == OldPLABSize, "Error");
2645 // In some cases, when the application has a phase change,
2646 // there may be a sudden and sharp shift in the object survival
2647 // profile, and updating the counts at the end of a scavenge
2648 // may not be quick enough, giving rise to large scavenge pauses
2649 // during these phase changes. It is beneficial to detect such
2650 // changes on-the-fly during a scavenge and avoid such a phase-change
2651 // pothole. The following code is a heuristic attempt to do that.
2652 // It is protected by a product flag until we have gained
2653 // enough experience with this heuristic and fine-tuned its behaviour.
2654 // WARNING: This might increase fragmentation if we overreact to
2655 // small spikes, so some kind of historical smoothing based on
2656 // previous experience with the greater reactivity might be useful.
2657 // Lacking sufficient experience, CMSOldPLABResizeQuicker is disabled by
2658 // default.
2659 if (ResizeOldPLAB && CMSOldPLABResizeQuicker) {
2660 size_t multiple = _num_blocks[word_sz]/(CMSOldPLABToleranceFactor*CMSOldPLABNumRefills*n_blks);
2661 n_blks += CMSOldPLABReactivityFactor*multiple*n_blks;
2662 n_blks = MIN2(n_blks, CMSOldPLABMax);
2663 }
2664 assert(n_blks > 0, "Error");
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2624 // If it didn't work, give up.
2625 if (fl->count() == 0) return NULL;
2626 }
2627 res = fl->get_chunk_at_head();
2628 assert(res != NULL, "Why was count non-zero?");
2629 }
2630 res->markNotFree();
2631 assert(!res->is_free(), "shouldn't be marked free");
2632 assert(oop(res)->klass_or_null() == NULL, "should look uninitialized");
2633 // mangle a just allocated object with a distinct pattern.
2634 debug_only(res->mangleAllocated(word_sz));
2635 return (HeapWord*)res;
2636 }
2637
2638 // Get a chunk of blocks of the right size and update related
2639 // book-keeping stats
2640 void CFLS_LAB::get_from_global_pool(size_t word_sz, AdaptiveFreeList<FreeChunk>* fl) {
2641 // Get the #blocks we want to claim
2642 size_t n_blks = (size_t)_blocks_to_claim[word_sz].average();
2643 assert(n_blks > 0, "Error");
2644 assert(ResizeOldPLAB || n_blks == OldPLABSize, "Error");
2645 // In some cases, when the application has a phase change,
2646 // there may be a sudden and sharp shift in the object survival
2647 // profile, and updating the counts at the end of a scavenge
2648 // may not be quick enough, giving rise to large scavenge pauses
2649 // during these phase changes. It is beneficial to detect such
2650 // changes on-the-fly during a scavenge and avoid such a phase-change
2651 // pothole. The following code is a heuristic attempt to do that.
2652 // It is protected by a product flag until we have gained
2653 // enough experience with this heuristic and fine-tuned its behaviour.
2654 // WARNING: This might increase fragmentation if we overreact to
2655 // small spikes, so some kind of historical smoothing based on
2656 // previous experience with the greater reactivity might be useful.
2657 // Lacking sufficient experience, CMSOldPLABResizeQuicker is disabled by
2658 // default.
2659 if (ResizeOldPLAB && CMSOldPLABResizeQuicker) {
2660 size_t multiple = _num_blocks[word_sz]/(CMSOldPLABToleranceFactor*CMSOldPLABNumRefills*n_blks);
2661 n_blks += CMSOldPLABReactivityFactor*multiple*n_blks;
2662 n_blks = MIN2(n_blks, CMSOldPLABMax);
2663 }
2664 assert(n_blks > 0, "Error");
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