tree d3660490ac539970b875a49c9032c5c946282cbf
parent a4e884a311893b476893739901bed382cd62b4fe
author David S. Miller <[EMAIL PROTECTED]> Mon, 18 Apr 2005 08:03:09 -0700
committer Linus Torvalds <[EMAIL PROTECTED]> Mon, 18 Apr 2005 08:03:09 -0700
[PATCH] sparc64: Do not flush dcache for ZERO_PAGE.
This case actually can get exercised a lot during an ELF
coredump of a process which contains a lot of non-COW'd
anonymous pages. GDB has this test case which in partiaular
creates near terabyte process full of ZERO_PAGEes. It takes
forever to just walk through the page tables because of
all of these spurious cache flushes on sparc64.
With this change it takes only a second or so.
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
sparc64/mm/init.c | 19 +++++++++++++++----
1 files changed, 15 insertions(+), 4 deletions(-)
Index: arch/sparc64/mm/init.c
===================================================================
--- 7b7b52678b61dfdf8e3a16b0e920d1e9b0cae979/arch/sparc64/mm/init.c
(mode:100644 sha1:89022ccaa75bbc722a8a26477f1bb2a086df719a)
+++ d3660490ac539970b875a49c9032c5c946282cbf/arch/sparc64/mm/init.c
(mode:100644 sha1:db6fa77b4dab67463c14c43da29fd5ee3284abf2)
@@ -201,13 +201,24 @@
void flush_dcache_page(struct page *page)
{
- struct address_space *mapping = page_mapping(page);
- int dirty = test_bit(PG_dcache_dirty, &page->flags);
- int dirty_cpu = dcache_dirty_cpu(page);
- int this_cpu = get_cpu();
+ struct address_space *mapping;
+ int this_cpu;
+ /* Do not bother with the expensive D-cache flush if it
+ * is merely the zero page. The 'bigcore' testcase in GDB
+ * causes this case to run millions of times.
+ */
+ if (page == ZERO_PAGE(0))
+ return;
+
+ this_cpu = get_cpu();
+
+ mapping = page_mapping(page);
if (mapping && !mapping_mapped(mapping)) {
+ int dirty = test_bit(PG_dcache_dirty, &page->flags);
if (dirty) {
+ int dirty_cpu = dcache_dirty_cpu(page);
+
if (dirty_cpu == this_cpu)
goto out;
smp_flush_dcache_page_impl(page, dirty_cpu);
-
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