6883834: ParNew: assert(!_g->to()->is_in_reserved(obj),"Scanning field twice?") with LargeObjects tests
Fixed process_chunk_boundaries(), used for parallel card scanning when using ParNew/CMS, so as to prevent double-scanning, or worse, non-scanning of imprecisely marked objects exceeding parallel chunk size. Made some sizing parameters for parallel card scanning diagnostic, disabled ParallelGCRetainPLAB, and elaborated and clarified some comments. Reviewed-by: stefank, johnc
This commit is contained in:
Y. Srinivas Ramakrishna
parent
90ab9d500c
commit
8e56205189
@ -29,13 +29,14 @@
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#include "memory/sharedHeap.hpp"
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#include "memory/space.inline.hpp"
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#include "memory/universe.hpp"
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#include "oops/oop.inline.hpp"
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#include "runtime/java.hpp"
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#include "runtime/mutexLocker.hpp"
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#include "runtime/virtualspace.hpp"
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void CardTableModRefBS::non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr,
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DirtyCardToOopClosure* dcto_cl,
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ClearNoncleanCardWrapper* cl,
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OopsInGenClosure* cl,
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CardTableRS* ct,
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int n_threads) {
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assert(n_threads > 0, "Error: expected n_threads > 0");
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assert((n_threads == 1 && ParallelGCThreads == 0) ||
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@ -49,14 +50,14 @@ void CardTableModRefBS::non_clean_card_iterate_parallel_work(Space* sp, MemRegio
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lowest_non_clean_base_chunk_index,
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lowest_non_clean_chunk_size);
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int n_strides = n_threads * StridesPerThread;
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int n_strides = n_threads * ParGCStridesPerThread;
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SequentialSubTasksDone* pst = sp->par_seq_tasks();
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pst->set_n_threads(n_threads);
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pst->set_n_tasks(n_strides);
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int stride = 0;
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while (!pst->is_task_claimed(/* reference */ stride)) {
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process_stride(sp, mr, stride, n_strides, dcto_cl, cl,
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process_stride(sp, mr, stride, n_strides, cl, ct,
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lowest_non_clean,
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lowest_non_clean_base_chunk_index,
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lowest_non_clean_chunk_size);
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@ -79,13 +80,13 @@ CardTableModRefBS::
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process_stride(Space* sp,
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MemRegion used,
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jint stride, int n_strides,
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DirtyCardToOopClosure* dcto_cl,
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ClearNoncleanCardWrapper* cl,
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OopsInGenClosure* cl,
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CardTableRS* ct,
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jbyte** lowest_non_clean,
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uintptr_t lowest_non_clean_base_chunk_index,
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size_t lowest_non_clean_chunk_size) {
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// We don't have to go downwards here; it wouldn't help anyway,
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// because of parallelism.
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// We go from higher to lower addresses here; it wouldn't help that much
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// because of the strided parallelism pattern used here.
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// Find the first card address of the first chunk in the stride that is
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// at least "bottom" of the used region.
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@ -98,25 +99,35 @@ process_stride(Space* sp,
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if ((uintptr_t)stride >= start_chunk_stride_num) {
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chunk_card_start = (jbyte*)(start_card +
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(stride - start_chunk_stride_num) *
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CardsPerStrideChunk);
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ParGCCardsPerStrideChunk);
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} else {
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// Go ahead to the next chunk group boundary, then to the requested stride.
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chunk_card_start = (jbyte*)(start_card +
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(n_strides - start_chunk_stride_num + stride) *
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CardsPerStrideChunk);
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ParGCCardsPerStrideChunk);
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}
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while (chunk_card_start < end_card) {
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// We don't have to go downwards here; it wouldn't help anyway,
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// because of parallelism. (We take care with "min_done"; see below.)
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// Even though we go from lower to higher addresses below, the
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// strided parallelism can interleave the actual processing of the
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// dirty pages in various ways. For a specific chunk within this
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// stride, we take care to avoid double scanning or missing a card
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// by suitably initializing the "min_done" field in process_chunk_boundaries()
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// below, together with the dirty region extension accomplished in
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// DirtyCardToOopClosure::do_MemRegion().
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jbyte* chunk_card_end = chunk_card_start + ParGCCardsPerStrideChunk;
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// Invariant: chunk_mr should be fully contained within the "used" region.
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jbyte* chunk_card_end = chunk_card_start + CardsPerStrideChunk;
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MemRegion chunk_mr = MemRegion(addr_for(chunk_card_start),
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chunk_card_end >= end_card ?
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used.end() : addr_for(chunk_card_end));
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assert(chunk_mr.word_size() > 0, "[chunk_card_start > used_end)");
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assert(used.contains(chunk_mr), "chunk_mr should be subset of used");
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DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision(),
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cl->gen_boundary());
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ClearNoncleanCardWrapper clear_cl(dcto_cl, ct);
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// Process the chunk.
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process_chunk_boundaries(sp,
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dcto_cl,
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@ -126,17 +137,30 @@ process_stride(Space* sp,
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lowest_non_clean_base_chunk_index,
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lowest_non_clean_chunk_size);
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// We want the LNC array updates above in process_chunk_boundaries
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// to be visible before any of the card table value changes as a
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// result of the dirty card iteration below.
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OrderAccess::storestore();
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// We do not call the non_clean_card_iterate_serial() version because
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// we want to clear the cards, and the ClearNoncleanCardWrapper closure
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// itself does the work of finding contiguous dirty ranges of cards to
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// process (and clear).
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cl->do_MemRegion(chunk_mr);
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// we want to clear the cards: clear_cl here does the work of finding
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// contiguous dirty ranges of cards to process and clear.
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clear_cl.do_MemRegion(chunk_mr);
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// Find the next chunk of the stride.
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chunk_card_start += CardsPerStrideChunk * n_strides;
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chunk_card_start += ParGCCardsPerStrideChunk * n_strides;
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}
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}
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// If you want a talkative process_chunk_boundaries,
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// then #define NOISY(x) x
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#ifdef NOISY
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#error "Encountered a global preprocessor flag, NOISY, which might clash with local definition to follow"
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#else
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#define NOISY(x)
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#endif
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void
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CardTableModRefBS::
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process_chunk_boundaries(Space* sp,
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@ -147,127 +171,233 @@ process_chunk_boundaries(Space* sp,
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uintptr_t lowest_non_clean_base_chunk_index,
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size_t lowest_non_clean_chunk_size)
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{
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// We must worry about the chunk boundaries.
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// We must worry about non-array objects that cross chunk boundaries,
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// because such objects are both precisely and imprecisely marked:
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// .. if the head of such an object is dirty, the entire object
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// needs to be scanned, under the interpretation that this
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// was an imprecise mark
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// .. if the head of such an object is not dirty, we can assume
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// precise marking and it's efficient to scan just the dirty
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// cards.
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// In either case, each scanned reference must be scanned precisely
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// once so as to avoid cloning of a young referent. For efficiency,
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// our closures depend on this property and do not protect against
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// double scans.
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// First, set our max_to_do:
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HeapWord* max_to_do = NULL;
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uintptr_t cur_chunk_index = addr_to_chunk_index(chunk_mr.start());
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cur_chunk_index = cur_chunk_index - lowest_non_clean_base_chunk_index;
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if (chunk_mr.end() < used.end()) {
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// This is not the last chunk in the used region. What is the last
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// object?
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HeapWord* last_block = sp->block_start(chunk_mr.end());
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assert(last_block <= chunk_mr.end(), "In case this property changes.");
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if (last_block == chunk_mr.end()
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|| !sp->block_is_obj(last_block)) {
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max_to_do = chunk_mr.end();
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NOISY(tty->print_cr("===========================================================================");)
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NOISY(tty->print_cr(" process_chunk_boundary: Called with [" PTR_FORMAT "," PTR_FORMAT ")",
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chunk_mr.start(), chunk_mr.end());)
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// First, set "our" lowest_non_clean entry, which would be
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// used by the thread scanning an adjoining left chunk with
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// a non-array object straddling the mutual boundary.
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// Find the object that spans our boundary, if one exists.
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// first_block is the block possibly straddling our left boundary.
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HeapWord* first_block = sp->block_start(chunk_mr.start());
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assert((chunk_mr.start() != used.start()) || (first_block == chunk_mr.start()),
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"First chunk should always have a co-initial block");
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// Does the block straddle the chunk's left boundary, and is it
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// a non-array object?
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if (first_block < chunk_mr.start() // first block straddles left bdry
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&& sp->block_is_obj(first_block) // first block is an object
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&& !(oop(first_block)->is_objArray() // first block is not an array (arrays are precisely dirtied)
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|| oop(first_block)->is_typeArray())) {
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// Find our least non-clean card, so that a left neighbour
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// does not scan an object straddling the mutual boundary
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// too far to the right, and attempt to scan a portion of
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// that object twice.
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jbyte* first_dirty_card = NULL;
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jbyte* last_card_of_first_obj =
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byte_for(first_block + sp->block_size(first_block) - 1);
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jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
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jbyte* last_card_of_cur_chunk = byte_for(chunk_mr.last());
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jbyte* last_card_to_check =
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(jbyte*) MIN2((intptr_t) last_card_of_cur_chunk,
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(intptr_t) last_card_of_first_obj);
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// Note that this does not need to go beyond our last card
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// if our first object completely straddles this chunk.
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for (jbyte* cur = first_card_of_cur_chunk;
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cur <= last_card_to_check; cur++) {
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jbyte val = *cur;
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if (card_will_be_scanned(val)) {
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first_dirty_card = cur; break;
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} else {
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assert(!card_may_have_been_dirty(val), "Error");
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}
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}
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if (first_dirty_card != NULL) {
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NOISY(tty->print_cr(" LNC: Found a dirty card at " PTR_FORMAT " in current chunk",
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first_dirty_card);)
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assert(0 <= cur_chunk_index && cur_chunk_index < lowest_non_clean_chunk_size,
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"Bounds error.");
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assert(lowest_non_clean[cur_chunk_index] == NULL,
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"Write exactly once : value should be stable hereafter for this round");
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lowest_non_clean[cur_chunk_index] = first_dirty_card;
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} NOISY(else {
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tty->print_cr(" LNC: Found no dirty card in current chunk; leaving LNC entry NULL");
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// In the future, we could have this thread look for a non-NULL value to copy from its
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// right neighbour (up to the end of the first object).
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if (last_card_of_cur_chunk < last_card_of_first_obj) {
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tty->print_cr(" LNC: BEWARE!!! first obj straddles past right end of chunk:\n"
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" might be efficient to get value from right neighbour?");
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}
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})
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} else {
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// In this case we can help our neighbour by just asking them
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// to stop at our first card (even though it may not be dirty).
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NOISY(tty->print_cr(" LNC: first block is not a non-array object; setting LNC to first card of current chunk");)
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assert(lowest_non_clean[cur_chunk_index] == NULL, "Write once : value should be stable hereafter");
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jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
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lowest_non_clean[cur_chunk_index] = first_card_of_cur_chunk;
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}
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NOISY(tty->print_cr(" process_chunk_boundary: lowest_non_clean[" INTPTR_FORMAT "] = " PTR_FORMAT
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" which corresponds to the heap address " PTR_FORMAT,
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cur_chunk_index, lowest_non_clean[cur_chunk_index],
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(lowest_non_clean[cur_chunk_index] != NULL)
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? addr_for(lowest_non_clean[cur_chunk_index])
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: NULL);)
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NOISY(tty->print_cr("---------------------------------------------------------------------------");)
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// Next, set our own max_to_do, which will strictly/exclusively bound
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// the highest address that we will scan past the right end of our chunk.
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HeapWord* max_to_do = NULL;
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if (chunk_mr.end() < used.end()) {
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// This is not the last chunk in the used region.
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// What is our last block? We check the first block of
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// the next (right) chunk rather than strictly check our last block
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// because it's potentially more efficient to do so.
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HeapWord* const last_block = sp->block_start(chunk_mr.end());
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assert(last_block <= chunk_mr.end(), "In case this property changes.");
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if ((last_block == chunk_mr.end()) // our last block does not straddle boundary
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|| !sp->block_is_obj(last_block) // last_block isn't an object
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|| oop(last_block)->is_objArray() // last_block is an array (precisely marked)
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|| oop(last_block)->is_typeArray()) {
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max_to_do = chunk_mr.end();
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NOISY(tty->print_cr(" process_chunk_boundary: Last block on this card is not a non-array object;\n"
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" max_to_do left at " PTR_FORMAT, max_to_do);)
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} else {
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// It is an object and starts before the end of the current chunk.
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assert(last_block < chunk_mr.end(), "Tautology");
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// It is a non-array object that straddles the right boundary of this chunk.
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// last_obj_card is the card corresponding to the start of the last object
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// in the chunk. Note that the last object may not start in
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// the chunk.
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jbyte* last_obj_card = byte_for(last_block);
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if (!card_may_have_been_dirty(*last_obj_card)) {
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// The card containing the head is not dirty. Any marks in
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jbyte* const last_obj_card = byte_for(last_block);
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const jbyte val = *last_obj_card;
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if (!card_will_be_scanned(val)) {
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assert(!card_may_have_been_dirty(val), "Error");
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// The card containing the head is not dirty. Any marks on
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// subsequent cards still in this chunk must have been made
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// precisely; we can cap processing at the end.
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// precisely; we can cap processing at the end of our chunk.
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max_to_do = chunk_mr.end();
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NOISY(tty->print_cr(" process_chunk_boundary: Head of last object on this card is not dirty;\n"
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" max_to_do left at " PTR_FORMAT,
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max_to_do);)
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} else {
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// The last object must be considered dirty, and extends onto the
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// following chunk. Look for a dirty card in that chunk that will
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// bound our processing.
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jbyte* limit_card = NULL;
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size_t last_block_size = sp->block_size(last_block);
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jbyte* last_card_of_last_obj =
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const size_t last_block_size = sp->block_size(last_block);
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jbyte* const last_card_of_last_obj =
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byte_for(last_block + last_block_size - 1);
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jbyte* first_card_of_next_chunk = byte_for(chunk_mr.end());
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jbyte* const first_card_of_next_chunk = byte_for(chunk_mr.end());
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// This search potentially goes a long distance looking
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// for the next card that will be scanned. For example,
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// an object that is an array of primitives will not
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// have any cards covering regions interior to the array
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// that will need to be scanned. The scan can be terminated
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// at the last card of the next chunk. That would leave
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// limit_card as NULL and would result in "max_to_do"
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// being set with the LNC value or with the end
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// of the last block.
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jbyte* last_card_of_next_chunk = first_card_of_next_chunk +
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CardsPerStrideChunk;
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assert(byte_for(chunk_mr.end()) - byte_for(chunk_mr.start())
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== CardsPerStrideChunk, "last card of next chunk may be wrong");
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jbyte* last_card_to_check = (jbyte*) MIN2(last_card_of_last_obj,
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last_card_of_next_chunk);
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// for the next card that will be scanned, terminating
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// at the end of the last_block, if no earlier dirty card
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// is found.
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assert(byte_for(chunk_mr.end()) - byte_for(chunk_mr.start()) == ParGCCardsPerStrideChunk,
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"last card of next chunk may be wrong");
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for (jbyte* cur = first_card_of_next_chunk;
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cur <= last_card_to_check; cur++) {
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if (card_will_be_scanned(*cur)) {
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cur <= last_card_of_last_obj; cur++) {
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const jbyte val = *cur;
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if (card_will_be_scanned(val)) {
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NOISY(tty->print_cr(" Found a non-clean card " PTR_FORMAT " with value 0x%x",
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cur, (int)val);)
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limit_card = cur; break;
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} else {
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assert(!card_may_have_been_dirty(val), "Error: card can't be skipped");
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}
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}
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assert(0 <= cur_chunk_index+1 &&
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cur_chunk_index+1 < lowest_non_clean_chunk_size,
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"Bounds error.");
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// LNC for the next chunk
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jbyte* lnc_card = lowest_non_clean[cur_chunk_index+1];
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if (limit_card == NULL) {
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limit_card = lnc_card;
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}
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if (limit_card != NULL) {
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if (lnc_card != NULL) {
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limit_card = (jbyte*)MIN2((intptr_t)limit_card,
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(intptr_t)lnc_card);
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}
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max_to_do = addr_for(limit_card);
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assert(limit_card != NULL && max_to_do != NULL, "Error");
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NOISY(tty->print_cr(" process_chunk_boundary: Found a dirty card at " PTR_FORMAT
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" max_to_do set at " PTR_FORMAT " which is before end of last block in chunk: "
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PTR_FORMAT " + " PTR_FORMAT " = " PTR_FORMAT,
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limit_card, max_to_do, last_block, last_block_size, (last_block+last_block_size));)
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} else {
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// The following is a pessimistic value, because it's possible
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// that a dirty card on a subsequent chunk has been cleared by
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// the time we get to look at it; we'll correct for that further below,
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// using the LNC array which records the least non-clean card
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// before cards were cleared in a particular chunk.
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limit_card = last_card_of_last_obj;
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max_to_do = last_block + last_block_size;
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assert(limit_card != NULL && max_to_do != NULL, "Error");
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NOISY(tty->print_cr(" process_chunk_boundary: Found no dirty card before end of last block in chunk\n"
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" Setting limit_card to " PTR_FORMAT
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" and max_to_do " PTR_FORMAT " + " PTR_FORMAT " = " PTR_FORMAT,
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limit_card, last_block, last_block_size, max_to_do);)
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}
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assert(0 < cur_chunk_index+1 && cur_chunk_index+1 < lowest_non_clean_chunk_size,
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"Bounds error.");
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// It is possible that a dirty card for the last object may have been
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// cleared before we had a chance to examine it. In that case, the value
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// will have been logged in the LNC for that chunk.
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// We need to examine as many chunks to the right as this object
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// covers.
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const uintptr_t last_chunk_index_to_check = addr_to_chunk_index(last_block + last_block_size - 1)
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- lowest_non_clean_base_chunk_index;
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DEBUG_ONLY(const uintptr_t last_chunk_index = addr_to_chunk_index(used.end())
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- lowest_non_clean_base_chunk_index;)
|
||||
assert(last_chunk_index_to_check <= last_chunk_index,
|
||||
err_msg("Out of bounds: last_chunk_index_to_check " INTPTR_FORMAT
|
||||
" exceeds last_chunk_index " INTPTR_FORMAT,
|
||||
last_chunk_index_to_check, last_chunk_index));
|
||||
for (uintptr_t lnc_index = cur_chunk_index + 1;
|
||||
lnc_index <= last_chunk_index_to_check;
|
||||
lnc_index++) {
|
||||
jbyte* lnc_card = lowest_non_clean[lnc_index];
|
||||
if (lnc_card != NULL) {
|
||||
// we can stop at the first non-NULL entry we find
|
||||
if (lnc_card <= limit_card) {
|
||||
NOISY(tty->print_cr(" process_chunk_boundary: LNC card " PTR_FORMAT " is lower than limit_card " PTR_FORMAT,
|
||||
" max_to_do will be lowered to " PTR_FORMAT " from " PTR_FORMAT,
|
||||
lnc_card, limit_card, addr_for(lnc_card), max_to_do);)
|
||||
limit_card = lnc_card;
|
||||
max_to_do = addr_for(limit_card);
|
||||
assert(limit_card != NULL && max_to_do != NULL, "Error");
|
||||
}
|
||||
// In any case, we break now
|
||||
break;
|
||||
} // else continue to look for a non-NULL entry if any
|
||||
}
|
||||
assert(limit_card != NULL && max_to_do != NULL, "Error");
|
||||
}
|
||||
assert(max_to_do != NULL, "OOPS 1 !");
|
||||
}
|
||||
assert(max_to_do != NULL, "OOPS!");
|
||||
assert(max_to_do != NULL, "OOPS 2!");
|
||||
} else {
|
||||
max_to_do = used.end();
|
||||
NOISY(tty->print_cr(" process_chunk_boundary: Last chunk of this space;\n"
|
||||
" max_to_do left at " PTR_FORMAT,
|
||||
max_to_do);)
|
||||
}
|
||||
assert(max_to_do != NULL, "OOPS 3!");
|
||||
// Now we can set the closure we're using so it doesn't to beyond
|
||||
// max_to_do.
|
||||
dcto_cl->set_min_done(max_to_do);
|
||||
#ifndef PRODUCT
|
||||
dcto_cl->set_last_bottom(max_to_do);
|
||||
#endif
|
||||
|
||||
// Now we set *our" lowest_non_clean entry.
|
||||
// Find the object that spans our boundary, if one exists.
|
||||
// Nothing to do on the first chunk.
|
||||
if (chunk_mr.start() > used.start()) {
|
||||
// first_block is the block possibly spanning the chunk start
|
||||
HeapWord* first_block = sp->block_start(chunk_mr.start());
|
||||
// Does the block span the start of the chunk and is it
|
||||
// an object?
|
||||
if (first_block < chunk_mr.start() &&
|
||||
sp->block_is_obj(first_block)) {
|
||||
jbyte* first_dirty_card = NULL;
|
||||
jbyte* last_card_of_first_obj =
|
||||
byte_for(first_block + sp->block_size(first_block) - 1);
|
||||
jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
|
||||
jbyte* last_card_of_cur_chunk = byte_for(chunk_mr.last());
|
||||
jbyte* last_card_to_check =
|
||||
(jbyte*) MIN2((intptr_t) last_card_of_cur_chunk,
|
||||
(intptr_t) last_card_of_first_obj);
|
||||
for (jbyte* cur = first_card_of_cur_chunk;
|
||||
cur <= last_card_to_check; cur++) {
|
||||
if (card_will_be_scanned(*cur)) {
|
||||
first_dirty_card = cur; break;
|
||||
}
|
||||
}
|
||||
if (first_dirty_card != NULL) {
|
||||
assert(0 <= cur_chunk_index &&
|
||||
cur_chunk_index < lowest_non_clean_chunk_size,
|
||||
"Bounds error.");
|
||||
lowest_non_clean[cur_chunk_index] = first_dirty_card;
|
||||
}
|
||||
}
|
||||
}
|
||||
NOISY(tty->print_cr("===========================================================================\n");)
|
||||
}
|
||||
|
||||
#undef NOISY
|
||||
|
||||
void
|
||||
CardTableModRefBS::
|
||||
get_LNC_array_for_space(Space* sp,
|
||||
@ -283,8 +413,8 @@ get_LNC_array_for_space(Space* sp,
|
||||
// LNC array for the covered region. Any later expansion can't affect
|
||||
// the used_at_save_marks region.
|
||||
// (I observed a bug in which the first thread to execute this would
|
||||
// resize, and then it would cause "expand_and_allocates" that would
|
||||
// Increase the number of chunks in the covered region. Then a second
|
||||
// resize, and then it would cause "expand_and_allocate" that would
|
||||
// increase the number of chunks in the covered region. Then a second
|
||||
// thread would come and execute this, see that the size didn't match,
|
||||
// and free and allocate again. So the first thread would be using a
|
||||
// freed "_lowest_non_clean" array.)
|
||||
|
||||
@ -77,7 +77,23 @@ inline void ParScanClosure::do_oop_work(T* p,
|
||||
if (!oopDesc::is_null(heap_oop)) {
|
||||
oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
|
||||
if ((HeapWord*)obj < _boundary) {
|
||||
assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?");
|
||||
#ifndef PRODUCT
|
||||
if (_g->to()->is_in_reserved(obj)) {
|
||||
tty->print_cr("Scanning field (" PTR_FORMAT ") twice?", p);
|
||||
GenCollectedHeap* gch = (GenCollectedHeap*)Universe::heap();
|
||||
Space* sp = gch->space_containing(p);
|
||||
oop obj = oop(sp->block_start(p));
|
||||
assert((HeapWord*)obj < (HeapWord*)p, "Error");
|
||||
tty->print_cr("Object: " PTR_FORMAT, obj);
|
||||
tty->print_cr("-------");
|
||||
obj->print();
|
||||
tty->print_cr("-----");
|
||||
tty->print_cr("Heap:");
|
||||
tty->print_cr("-----");
|
||||
gch->print();
|
||||
ShouldNotReachHere();
|
||||
}
|
||||
#endif
|
||||
// OK, we need to ensure that it is copied.
|
||||
// We read the klass and mark in this order, so that we can reliably
|
||||
// get the size of the object: if the mark we read is not a
|
||||
|
||||
@ -455,25 +455,29 @@ bool CardTableModRefBS::mark_card_deferred(size_t card_index) {
|
||||
return true;
|
||||
}
|
||||
|
||||
|
||||
void CardTableModRefBS::non_clean_card_iterate_possibly_parallel(Space* sp,
|
||||
MemRegion mr,
|
||||
DirtyCardToOopClosure* dcto_cl,
|
||||
ClearNoncleanCardWrapper* cl) {
|
||||
OopsInGenClosure* cl,
|
||||
CardTableRS* ct) {
|
||||
if (!mr.is_empty()) {
|
||||
int n_threads = SharedHeap::heap()->n_par_threads();
|
||||
if (n_threads > 0) {
|
||||
#ifndef SERIALGC
|
||||
non_clean_card_iterate_parallel_work(sp, mr, dcto_cl, cl, n_threads);
|
||||
non_clean_card_iterate_parallel_work(sp, mr, cl, ct, n_threads);
|
||||
#else // SERIALGC
|
||||
fatal("Parallel gc not supported here.");
|
||||
#endif // SERIALGC
|
||||
} else {
|
||||
// We do not call the non_clean_card_iterate_serial() version below because
|
||||
// we want to clear the cards (which non_clean_card_iterate_serial() does not
|
||||
// do for us), and the ClearNoncleanCardWrapper closure itself does the work
|
||||
// of finding contiguous dirty ranges of cards to process (and clear).
|
||||
cl->do_MemRegion(mr);
|
||||
// do for us): clear_cl here does the work of finding contiguous dirty ranges
|
||||
// of cards to process and clear.
|
||||
|
||||
DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision(),
|
||||
cl->gen_boundary());
|
||||
ClearNoncleanCardWrapper clear_cl(dcto_cl, ct);
|
||||
|
||||
clear_cl.do_MemRegion(mr);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
@ -173,18 +173,17 @@ class CardTableModRefBS: public ModRefBarrierSet {
|
||||
// A variant of the above that will operate in a parallel mode if
|
||||
// worker threads are available, and clear the dirty cards as it
|
||||
// processes them.
|
||||
// ClearNoncleanCardWrapper cl must wrap the DirtyCardToOopClosure dcto_cl,
|
||||
// which may itself be modified by the method.
|
||||
// XXX ??? MemRegionClosure above vs OopsInGenClosure below XXX
|
||||
// XXX some new_dcto_cl's take OopClosure's, plus as above there are
|
||||
// some MemRegionClosures. Clean this up everywhere. XXX
|
||||
void non_clean_card_iterate_possibly_parallel(Space* sp, MemRegion mr,
|
||||
DirtyCardToOopClosure* dcto_cl,
|
||||
ClearNoncleanCardWrapper* cl);
|
||||
OopsInGenClosure* cl, CardTableRS* ct);
|
||||
|
||||
private:
|
||||
// Work method used to implement non_clean_card_iterate_possibly_parallel()
|
||||
// above in the parallel case.
|
||||
void non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr,
|
||||
DirtyCardToOopClosure* dcto_cl,
|
||||
ClearNoncleanCardWrapper* cl,
|
||||
OopsInGenClosure* cl, CardTableRS* ct,
|
||||
int n_threads);
|
||||
|
||||
protected:
|
||||
@ -198,11 +197,6 @@ class CardTableModRefBS: public ModRefBarrierSet {
|
||||
|
||||
// *** Support for parallel card scanning.
|
||||
|
||||
enum SomeConstantsForParallelism {
|
||||
StridesPerThread = 2,
|
||||
CardsPerStrideChunk = 256
|
||||
};
|
||||
|
||||
// This is an array, one element per covered region of the card table.
|
||||
// Each entry is itself an array, with one element per chunk in the
|
||||
// covered region. Each entry of these arrays is the lowest non-clean
|
||||
@ -235,7 +229,7 @@ class CardTableModRefBS: public ModRefBarrierSet {
|
||||
// covers the given address.
|
||||
uintptr_t addr_to_chunk_index(const void* addr) {
|
||||
uintptr_t card = (uintptr_t) byte_for(addr);
|
||||
return card / CardsPerStrideChunk;
|
||||
return card / ParGCCardsPerStrideChunk;
|
||||
}
|
||||
|
||||
// Apply cl, which must either itself apply dcto_cl or be dcto_cl,
|
||||
@ -243,8 +237,8 @@ class CardTableModRefBS: public ModRefBarrierSet {
|
||||
void process_stride(Space* sp,
|
||||
MemRegion used,
|
||||
jint stride, int n_strides,
|
||||
DirtyCardToOopClosure* dcto_cl,
|
||||
ClearNoncleanCardWrapper* cl,
|
||||
OopsInGenClosure* cl,
|
||||
CardTableRS* ct,
|
||||
jbyte** lowest_non_clean,
|
||||
uintptr_t lowest_non_clean_base_chunk_index,
|
||||
size_t lowest_non_clean_chunk_size);
|
||||
@ -482,7 +476,7 @@ public:
|
||||
void verify_dirty_region(MemRegion mr) PRODUCT_RETURN;
|
||||
|
||||
static size_t par_chunk_heapword_alignment() {
|
||||
return CardsPerStrideChunk * card_size_in_words;
|
||||
return ParGCCardsPerStrideChunk * card_size_in_words;
|
||||
}
|
||||
|
||||
};
|
||||
|
||||
@ -162,7 +162,7 @@ inline bool ClearNoncleanCardWrapper::clear_card_serial(jbyte* entry) {
|
||||
}
|
||||
|
||||
ClearNoncleanCardWrapper::ClearNoncleanCardWrapper(
|
||||
MemRegionClosure* dirty_card_closure, CardTableRS* ct) :
|
||||
DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct) :
|
||||
_dirty_card_closure(dirty_card_closure), _ct(ct) {
|
||||
_is_par = (SharedHeap::heap()->n_par_threads() > 0);
|
||||
}
|
||||
@ -246,10 +246,6 @@ void CardTableRS::write_ref_field_gc_par(void* field, oop new_val) {
|
||||
|
||||
void CardTableRS::younger_refs_in_space_iterate(Space* sp,
|
||||
OopsInGenClosure* cl) {
|
||||
DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, _ct_bs->precision(),
|
||||
cl->gen_boundary());
|
||||
ClearNoncleanCardWrapper clear_cl(dcto_cl, this);
|
||||
|
||||
const MemRegion urasm = sp->used_region_at_save_marks();
|
||||
#ifdef ASSERT
|
||||
// Convert the assertion check to a warning if we are running
|
||||
@ -275,10 +271,10 @@ void CardTableRS::younger_refs_in_space_iterate(Space* sp,
|
||||
if (!urasm.equals(urasm2)) {
|
||||
warning("CMS+ParNew: Flickering used_region_at_save_marks()!!");
|
||||
}
|
||||
ShouldNotReachHere();
|
||||
}
|
||||
#endif
|
||||
_ct_bs->non_clean_card_iterate_possibly_parallel(sp, urasm,
|
||||
dcto_cl, &clear_cl);
|
||||
_ct_bs->non_clean_card_iterate_possibly_parallel(sp, urasm, cl, this);
|
||||
}
|
||||
|
||||
void CardTableRS::clear_into_younger(Generation* gen, bool clear_perm) {
|
||||
|
||||
@ -31,7 +31,6 @@
|
||||
|
||||
class Space;
|
||||
class OopsInGenClosure;
|
||||
class DirtyCardToOopClosure;
|
||||
|
||||
// This kind of "GenRemSet" uses a card table both as shared data structure
|
||||
// for a mod ref barrier set and for the rem set information.
|
||||
@ -167,7 +166,7 @@ public:
|
||||
};
|
||||
|
||||
class ClearNoncleanCardWrapper: public MemRegionClosure {
|
||||
MemRegionClosure* _dirty_card_closure;
|
||||
DirtyCardToOopClosure* _dirty_card_closure;
|
||||
CardTableRS* _ct;
|
||||
bool _is_par;
|
||||
private:
|
||||
@ -179,7 +178,7 @@ private:
|
||||
inline bool clear_card_parallel(jbyte* entry);
|
||||
|
||||
public:
|
||||
ClearNoncleanCardWrapper(MemRegionClosure* dirty_card_closure, CardTableRS* ct);
|
||||
ClearNoncleanCardWrapper(DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct);
|
||||
void do_MemRegion(MemRegion mr);
|
||||
};
|
||||
|
||||
|
||||
@ -97,6 +97,14 @@ void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
|
||||
}
|
||||
}
|
||||
|
||||
// We get called with "mr" representing the dirty region
|
||||
// that we want to process. Because of imprecise marking,
|
||||
// we may need to extend the incoming "mr" to the right,
|
||||
// and scan more. However, because we may already have
|
||||
// scanned some of that extended region, we may need to
|
||||
// trim its right-end back some so we do not scan what
|
||||
// we (or another worker thread) may already have scanned
|
||||
// or planning to scan.
|
||||
void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
|
||||
|
||||
// Some collectors need to do special things whenever their dirty
|
||||
@ -148,7 +156,7 @@ void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
|
||||
// e.g. the dirty card region is entirely in a now free object
|
||||
// -- something that could happen with a concurrent sweeper.
|
||||
bottom = MIN2(bottom, top);
|
||||
mr = MemRegion(bottom, top);
|
||||
MemRegion extended_mr = MemRegion(bottom, top);
|
||||
assert(bottom <= top &&
|
||||
(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
|
||||
_min_done == NULL ||
|
||||
@ -156,8 +164,8 @@ void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
|
||||
"overlap!");
|
||||
|
||||
// Walk the region if it is not empty; otherwise there is nothing to do.
|
||||
if (!mr.is_empty()) {
|
||||
walk_mem_region(mr, bottom_obj, top);
|
||||
if (!extended_mr.is_empty()) {
|
||||
walk_mem_region(extended_mr, bottom_obj, top);
|
||||
}
|
||||
|
||||
// An idempotent closure might be applied in any order, so we don't
|
||||
|
||||
@ -1460,8 +1460,10 @@ class CommandLineFlags {
|
||||
product(intx, ParallelGCBufferWastePct, 10, \
|
||||
"wasted fraction of parallel allocation buffer.") \
|
||||
\
|
||||
product(bool, ParallelGCRetainPLAB, true, \
|
||||
"Retain parallel allocation buffers across scavenges.") \
|
||||
diagnostic(bool, ParallelGCRetainPLAB, false, \
|
||||
"Retain parallel allocation buffers across scavenges; " \
|
||||
" -- disabled because this currently conflicts with " \
|
||||
" parallel card scanning under certain conditions ") \
|
||||
\
|
||||
product(intx, TargetPLABWastePct, 10, \
|
||||
"target wasted space in last buffer as pct of overall allocation")\
|
||||
@ -1495,7 +1497,15 @@ class CommandLineFlags {
|
||||
product(uintx, ParGCDesiredObjsFromOverflowList, 20, \
|
||||
"The desired number of objects to claim from the overflow list") \
|
||||
\
|
||||
product(uintx, CMSParPromoteBlocksToClaim, 16, \
|
||||
diagnostic(intx, ParGCStridesPerThread, 2, \
|
||||
"The number of strides per worker thread that we divide up the " \
|
||||
"card table scanning work into") \
|
||||
\
|
||||
diagnostic(intx, ParGCCardsPerStrideChunk, 256, \
|
||||
"The number of cards in each chunk of the parallel chunks used " \
|
||||
"during card table scanning") \
|
||||
\
|
||||
product(uintx, CMSParPromoteBlocksToClaim, 16, \
|
||||
"Number of blocks to attempt to claim when refilling CMS LAB for "\
|
||||
"parallel GC.") \
|
||||
\
|
||||
|
||||
Loading…
Reference in New Issue
Block a user