implement the speculative find_get_pages_tag.
Signed-off-by: Peter Zijlstra <[email protected]>
---
mm/filemap.c | 42 +++++++++++++++++++++++++++++++++---------
1 file changed, 33 insertions(+), 9 deletions(-)
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c 2007-01-22 20:11:07.000000000 +0100
+++ linux-2.6/mm/filemap.c 2007-01-22 20:11:09.000000000 +0100
@@ -849,16 +849,40 @@ unsigned find_get_pages_tag(struct addre
{
unsigned int i;
unsigned int ret;
+ unsigned int nr_found;
- read_lock_irq(&mapping->tree_lock);
- /* TODO: implement lookup_tag_slot and make this lockless */
- ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
- (void **)pages, *index, nr_pages, tag);
- for (i = 0; i < ret; i++)
- page_cache_get(pages[i]);
- if (ret)
- *index = pages[ret - 1]->index + 1;
- read_unlock_irq(&mapping->tree_lock);
+ rcu_read_lock();
+restart:
+ nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree,
+ (void ***)pages, *index, nr_pages, tag);
+
+ ret = 0;
+ for (i = 0; i < nr_found; i++) {
+ struct page *page;
+repeat:
+ page = radix_tree_deref_slot((void**)pages[i]);
+ if (unlikely(!page))
+ continue;
+ /*
+ * this can only trigger if nr_found == 1, making livelocks
+ * a non issue.
+ */
+ if (unlikely(page == RADIX_TREE_RETRY))
+ goto restart;
+
+ if (!page_cache_get_speculative(page))
+ goto repeat;
+
+ /* Has the page moved? */
+ if (unlikely(page != *((void **)pages[i]))) {
+ page_cache_release(page);
+ goto repeat;
+ }
+
+ pages[ret] = page;
+ ret++;
+ }
+ rcu_read_unlock();
return ret;
}
--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
