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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2008-08-01 16:39:12 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2008-08-01 16:39:30 +0200
commita4b526b3ba6353cd89a38e41da48ed83b0ead16f (patch)
tree362842354bdcde59feede51cbeefc9b8833aacf7
parent934b2857cc576ae53c92a66e63fce7ddcfa74691 (diff)
[S390] Optimize storage key operations for anon pages
For anonymous pages without a swap cache backing the check in page_remove_rmap for the physical dirty bit in page_remove_rmap is unnecessary. The instructions that are used to check and reset the dirty bit are expensive. Removing the check noticably speeds up process exit. In addition the clearing of the dirty bit in __SetPageUptodate is pointless as well. With these two changes there is no storage key operation for an anonymous page anymore if it does not hit the swap space. The micro benchmark which repeatedly executes an empty shell script gets about 5% faster. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
-rw-r--r--include/linux/page-flags.h3
-rw-r--r--mm/rmap.c3
2 files changed, 2 insertions, 4 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 54590a9a103e..25aaccdb2f26 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -239,9 +239,6 @@ static inline void __SetPageUptodate(struct page *page)
{
smp_wmb();
__set_bit(PG_uptodate, &(page)->flags);
-#ifdef CONFIG_S390
- page_clear_dirty(page);
-#endif
}
static inline void SetPageUptodate(struct page *page)
diff --git a/mm/rmap.c b/mm/rmap.c
index 99bc3f9cd796..94a5246a3f98 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -667,7 +667,8 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
* Leaving it set also helps swapoff to reinstate ptes
* faster for those pages still in swapcache.
*/
- if (page_test_dirty(page)) {
+ if ((!PageAnon(page) || PageSwapCache(page)) &&
+ page_test_dirty(page)) {
page_clear_dirty(page);
set_page_dirty(page);
}

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