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Changed Heap::Shrink to free as many pages as possible.

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As a benefit, this eliminates an ifdef ARDROID.

Review URL: http://codereview.chromium.org/165453

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2685 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
bak@chromium.org 2009-08-13 14:58:35 +00:00
parent 9373ca76ed
commit f1f776f947
1 changed files with 13 additions and 35 deletions
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48
src/spaces.cc
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@ -726,47 +726,25 @@ void PagedSpace::Shrink() {
Page* top_page = AllocationTopPage();
ASSERT(top_page->is_valid());
// Loop over the pages from the top page to the end of the space to count
// the number of pages to keep and find the last page to keep.
int free_pages = 0;
int pages_to_keep = 0; // Of the free pages.
Page* last_page_to_keep = top_page;
Page* current_page = top_page->next_page();
// Loop over the pages to the end of the space.
while (current_page->is_valid()) {
#if defined(ANDROID)
// Free all chunks if possible
#else
// Advance last_page_to_keep every other step to end up at the midpoint.
if ((free_pages & 0x1) == 1) {
pages_to_keep++;
last_page_to_keep = last_page_to_keep->next_page();
}
#endif
free_pages++;
current_page = current_page->next_page();
// Count the number of pages we would like to free.
int pages_to_free = 0;
for (Page* p = top_page->next_page(); p->is_valid(); p = p->next_page()) {
pages_to_free++;
}
// Free pages after last_page_to_keep, and adjust the next_page link.
Page* p = MemoryAllocator::FreePages(last_page_to_keep->next_page());
MemoryAllocator::SetNextPage(last_page_to_keep, p);
// Free pages after top_page.
Page* p = MemoryAllocator::FreePages(top_page->next_page());
MemoryAllocator::SetNextPage(top_page, p);
// Since pages are only freed in whole chunks, we may have kept more
// than pages_to_keep. Count the extra pages and cache the new last
// page in the space.
last_page_ = last_page_to_keep;
while (p->is_valid()) {
pages_to_keep++;
// Find out how many pages we failed to free and update last_page_.
// Please note pages can only be freed in whole chunks.
last_page_ = top_page;
for (Page* p = top_page->next_page(); p->is_valid(); p = p->next_page()) {
pages_to_free--;
last_page_ = p;
p = p->next_page();
}
// The difference between free_pages and pages_to_keep is the number of
// pages actually freed.
ASSERT(pages_to_keep <= free_pages);
int bytes_freed = (free_pages - pages_to_keep) * Page::kObjectAreaSize;
accounting_stats_.ShrinkSpace(bytes_freed);
accounting_stats_.ShrinkSpace(pages_to_free * Page::kObjectAreaSize);
ASSERT(Capacity() == CountTotalPages() * Page::kObjectAreaSize);
}