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7037276: Unnecessary double traversal of dirty card windows

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Short-circuited an unnecessary double traversal of dirty card windows when iterating younger refs. Also renamed some cardtable methods for more clarity.

Reviewed-by: jmasa, stefank, poonam
This commit is contained in:
Y. Srinivas Ramakrishna 2011-04-20 19:19:30 -07:00
parent 12d1d9acc1
commit b4d40650b2
5 changed files with 198 additions and 162 deletions
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79
hotspot/src/share/vm/gc_implementation/parNew/parCardTableModRefBS.cpp
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@ -33,44 +33,43 @@
#include "runtime/mutexLocker.hpp"
#include "runtime/virtualspace.hpp"
void CardTableModRefBS::par_non_clean_card_iterate_work(Space* sp, MemRegion mr,
DirtyCardToOopClosure* dcto_cl,
MemRegionClosure* cl,
int n_threads) {
if (n_threads > 0) {
assert((n_threads == 1 && ParallelGCThreads == 0) ||
n_threads <= (int)ParallelGCThreads,
"# worker threads != # requested!");
// Make sure the LNC array is valid for the space.
jbyte** lowest_non_clean;
uintptr_t lowest_non_clean_base_chunk_index;
size_t lowest_non_clean_chunk_size;
get_LNC_array_for_space(sp, lowest_non_clean,
lowest_non_clean_base_chunk_index,
lowest_non_clean_chunk_size);
void CardTableModRefBS::non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr,
DirtyCardToOopClosure* dcto_cl,
ClearNoncleanCardWrapper* cl,
int n_threads) {
assert(n_threads > 0, "Error: expected n_threads > 0");
assert((n_threads == 1 && ParallelGCThreads == 0) ||
n_threads <= (int)ParallelGCThreads,
"# worker threads != # requested!");
// Make sure the LNC array is valid for the space.
jbyte** lowest_non_clean;
uintptr_t lowest_non_clean_base_chunk_index;
size_t lowest_non_clean_chunk_size;
get_LNC_array_for_space(sp, lowest_non_clean,
lowest_non_clean_base_chunk_index,
lowest_non_clean_chunk_size);
int n_strides = n_threads * StridesPerThread;
SequentialSubTasksDone* pst = sp->par_seq_tasks();
pst->set_n_threads(n_threads);
pst->set_n_tasks(n_strides);
int n_strides = n_threads * StridesPerThread;
SequentialSubTasksDone* pst = sp->par_seq_tasks();
pst->set_n_threads(n_threads);
pst->set_n_tasks(n_strides);
int stride = 0;
while (!pst->is_task_claimed(/* reference */ stride)) {
process_stride(sp, mr, stride, n_strides, dcto_cl, cl,
lowest_non_clean,
lowest_non_clean_base_chunk_index,
lowest_non_clean_chunk_size);
}
if (pst->all_tasks_completed()) {
// Clear lowest_non_clean array for next time.
intptr_t first_chunk_index = addr_to_chunk_index(mr.start());
uintptr_t last_chunk_index = addr_to_chunk_index(mr.last());
for (uintptr_t ch = first_chunk_index; ch <= last_chunk_index; ch++) {
intptr_t ind = ch - lowest_non_clean_base_chunk_index;
assert(0 <= ind && ind < (intptr_t)lowest_non_clean_chunk_size,
"Bounds error");
lowest_non_clean[ind] = NULL;
}
int stride = 0;
while (!pst->is_task_claimed(/* reference */ stride)) {
process_stride(sp, mr, stride, n_strides, dcto_cl, cl,
lowest_non_clean,
lowest_non_clean_base_chunk_index,
lowest_non_clean_chunk_size);
}
if (pst->all_tasks_completed()) {
// Clear lowest_non_clean array for next time.
intptr_t first_chunk_index = addr_to_chunk_index(mr.start());
uintptr_t last_chunk_index = addr_to_chunk_index(mr.last());
for (uintptr_t ch = first_chunk_index; ch <= last_chunk_index; ch++) {
intptr_t ind = ch - lowest_non_clean_base_chunk_index;
assert(0 <= ind && ind < (intptr_t)lowest_non_clean_chunk_size,
"Bounds error");
lowest_non_clean[ind] = NULL;
}
}
}
@ -81,7 +80,7 @@ process_stride(Space* sp,
MemRegion used,
jint stride, int n_strides,
DirtyCardToOopClosure* dcto_cl,
MemRegionClosure* cl,
ClearNoncleanCardWrapper* cl,
jbyte** lowest_non_clean,
uintptr_t lowest_non_clean_base_chunk_index,
size_t lowest_non_clean_chunk_size) {
@ -127,7 +126,11 @@ process_stride(Space* sp,
lowest_non_clean_base_chunk_index,
lowest_non_clean_chunk_size);
non_clean_card_iterate_work(chunk_mr, cl);
// We do not call the non_clean_card_iterate_serial() version because
// we want to clear the cards, and the ClearNoncleanCardWrapper closure
// itself does the work of finding contiguous dirty ranges of cards to
// process (and clear).
cl->do_MemRegion(chunk_mr);
// Find the next chunk of the stride.
chunk_card_start += CardsPerStrideChunk * n_strides;