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src/share/vm/runtime/os.cpp
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rev 7654 : 8066875: VirtualSpace does not use large pages
rev 7655 : 8066875: VirtualSpace does not use large pages (01)
rev 7656 : 8066875: VirtualSpace does not use large pages (02)
@@ -1397,26 +1397,36 @@
// The very lower end of the stack
address stack_limit = thread->stack_base() - thread->stack_size();
return (sp > (stack_limit + reserved_area));
}
-size_t os::page_size_for_region(size_t region_size, size_t min_pages) {
+size_t os::page_size_for_region(size_t region_size, size_t min_pages, bool must_be_aligned) {
assert(min_pages > 0, "sanity");
if (UseLargePages) {
const size_t max_page_size = region_size / min_pages;
for (size_t i = 0; _page_sizes[i] != 0; ++i) {
const size_t page_size = _page_sizes[i];
- if (page_size <= max_page_size && is_size_aligned(region_size, page_size)) {
+ if (page_size <= max_page_size) {
+ if (!must_be_aligned || is_size_aligned(region_size, page_size)) {
return page_size;
}
}
}
+ }
return vm_page_size();
}
+size_t os::page_size_for_region_aligned(size_t region_size, size_t min_pages) {
+ return page_size_for_region(region_size, min_pages, true);
+}
+
+size_t os::page_size_for_region_unaligned(size_t region_size, size_t min_pages) {
+ return page_size_for_region(region_size, min_pages, false);
+}
+
#ifndef PRODUCT
void os::trace_page_sizes(const char* str, const size_t* page_sizes, int count)
{
if (TracePageSizes) {
tty->print("%s: ", str);
@@ -1661,21 +1671,21 @@
return os::vm_page_size();
}
static size_t large_page_size() {
const size_t large_page_size_example = 4 * M;
- return os::page_size_for_region(large_page_size_example, 1);
+ return os::page_size_for_region_aligned(large_page_size_example, 1);
}
- static void test_page_size_for_region() {
+ static void test_page_size_for_region_aligned() {
if (UseLargePages) {
const size_t small_page = small_page_size();
const size_t large_page = large_page_size();
if (large_page > small_page) {
size_t num_small_pages_in_large = large_page / small_page;
- size_t page = os::page_size_for_region(large_page, num_small_pages_in_large);
+ size_t page = os::page_size_for_region_aligned(large_page, num_small_pages_in_large);
assert_eq(page, small_page);
}
}
}
@@ -1684,25 +1694,57 @@
if (UseLargePages) {
const size_t small_page = small_page_size();
const size_t large_page = large_page_size();
if (large_page > small_page) {
const size_t unaligned_region = large_page + 17;
- size_t page = os::page_size_for_region(unaligned_region, 1);
+ size_t page = os::page_size_for_region_aligned(unaligned_region, 1);
assert_eq(page, small_page);
const size_t num_pages = 5;
const size_t aligned_region = large_page * num_pages;
- page = os::page_size_for_region(aligned_region, num_pages);
+ page = os::page_size_for_region_aligned(aligned_region, num_pages);
assert_eq(page, large_page);
}
}
}
+ static void test_page_size_for_region_unaligned() {
+ if (UseLargePages) {
+ // Given exact page size, should return that page size.
+ for (size_t i = 0; os::_page_sizes[i] != 0; i++) {
+ size_t expected = os::_page_sizes[i];
+ size_t actual = os::page_size_for_region_unaligned(expected, 1);
+ assert_eq(expected, actual);
+ }
+
+ // Given slightly larger size than a page size, return the page size.
+ for (size_t i = 0; os::_page_sizes[i] != 0; i++) {
+ size_t expected = os::_page_sizes[i];
+ size_t actual = os::page_size_for_region_unaligned(expected + 17, 1);
+ assert_eq(expected, actual);
+ }
+
+ // Given a slightly smaller size than a page size,
+ // return the next smaller page size.
+ if (os::_page_sizes[1] > os::_page_sizes[0]) {
+ size_t expected = os::_page_sizes[0];
+ size_t actual = os::page_size_for_region_unaligned(os::_page_sizes[1] - 17, 1);
+ assert_eq(actual, expected);
+ }
+
+ // Return small page size for values less than a small page.
+ size_t small_page = small_page_size();
+ size_t actual = os::page_size_for_region_unaligned(small_page - 17, 1);
+ assert_eq(small_page, actual);
+ }
+ }
+
public:
static void run_tests() {
- test_page_size_for_region();
+ test_page_size_for_region_aligned();
test_page_size_for_region_alignment();
+ test_page_size_for_region_unaligned();
}
};
void TestOS_test() {
TestOS::run_tests();
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