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 behavior.
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");
2665 _cfls->par_get_chunk_of_blocks(word_sz, n_blks, fl);
2666 // Update stats table entry for this block size
2667 _num_blocks[word_sz] += fl->count();
2668 }
2669
2670 void CFLS_LAB::compute_desired_plab_size() {
2671 for (size_t i = CompactibleFreeListSpace::IndexSetStart;
2672 i < CompactibleFreeListSpace::IndexSetSize;
2673 i += CompactibleFreeListSpace::IndexSetStride) {
2674 assert((_global_num_workers[i] == 0) == (_global_num_blocks[i] == 0),
2675 "Counter inconsistency");
2676 if (_global_num_workers[i] > 0) {
2677 // Need to smooth wrt historical average
2678 if (ResizeOldPLAB) {
2679 _blocks_to_claim[i].sample(
2680 MAX2((size_t)CMSOldPLABMin,
2681 MIN2((size_t)CMSOldPLABMax,
2682 _global_num_blocks[i]/(_global_num_workers[i]*CMSOldPLABNumRefills))));
|
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 behavior.
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, (size_t)CMSOldPLABMax);
2663 }
2664 assert(n_blks > 0, "Error");
2665 _cfls->par_get_chunk_of_blocks(word_sz, n_blks, fl);
2666 // Update stats table entry for this block size
2667 _num_blocks[word_sz] += fl->count();
2668 }
2669
2670 void CFLS_LAB::compute_desired_plab_size() {
2671 for (size_t i = CompactibleFreeListSpace::IndexSetStart;
2672 i < CompactibleFreeListSpace::IndexSetSize;
2673 i += CompactibleFreeListSpace::IndexSetStride) {
2674 assert((_global_num_workers[i] == 0) == (_global_num_blocks[i] == 0),
2675 "Counter inconsistency");
2676 if (_global_num_workers[i] > 0) {
2677 // Need to smooth wrt historical average
2678 if (ResizeOldPLAB) {
2679 _blocks_to_claim[i].sample(
2680 MAX2((size_t)CMSOldPLABMin,
2681 MIN2((size_t)CMSOldPLABMax,
2682 _global_num_blocks[i]/(_global_num_workers[i]*CMSOldPLABNumRefills))));
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