by The blockdev mapping's private_lock is fairly contended. The buffer
LRU cache fixed a lot of that, but under page replacement load,
try_to_free_buffers is still showing up.
Moving the freeing of buffer_heads outside the lock reduces contention
in there by 30%.
buffer.c | 24 +++++++++++++++++++-----
1 files changed, 19 insertions(+), 5 deletions(-)
--- 2.5.24/fs/buffer.c~ttfb_contention Thu Jul 4 16:17:34 2002
(bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
}
-static /*inline*/ int drop_buffers(struct page *page)
+static inline int
+drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
{
struct buffer_head *head = page_buffers(page);
if (!list_empty(&bh->b_assoc_buffers))
__remove_assoc_queue(bh);
- free_buffer_head(bh);
bh = next;
} while (bh != head);
+ *buffers_to_free = head;
__clear_page_buffers(page);
return 1;
int try_to_free_buffers(struct page *page)
{
struct address_space * const mapping = page->mapping;
+ struct buffer_head *buffers_to_free = NULL;
int ret = 0;
BUG_ON(!PageLocked(page));
if (PageWriteback(page))
return 0;
- if (mapping == NULL) /* swapped-in anon page */
- return drop_buffers(page);
+ if (mapping == NULL) { /* swapped-in anon page */
+ ret = drop_buffers(page, &buffers_to_free);
+ goto out;
+ }
spin_lock(&mapping->private_lock);
- ret = drop_buffers(page);
+ ret = drop_buffers(page, &buffers_to_free);
if (ret && !PageSwapCache(page)) {
/*
ClearPageDirty(page);
}
spin_unlock(&mapping->private_lock);
+out:
+ if (buffers_to_free) {
+ struct buffer_head *bh = buffers_to_free;
+
+ do {
+ struct buffer_head *next = bh->b_this_page;
+ free_buffer_head(bh);
+ bh = next;
+ } while (bh != buffers_to_free);
+ }
return ret;
}
EXPORT_SYMBOL(try_to_free_buffers);
-
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/