writeback: improve scalability of bdi writeback work queues

If you're going to do an atomic RMW on each list entry, there's not much
point in all the RCU complexities of the list walking. This is only going
to help the multi-thread case I guess, but it doesn't hurt to do now.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Nick Piggin 2009-09-15 21:34:12 +02:00 committed by Jens Axboe
parent deed62edff
commit 77fad5e625

View file

@ -772,8 +772,9 @@ static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi,
rcu_read_lock();
list_for_each_entry_rcu(work, &bdi->work_list, list) {
if (!test_and_clear_bit(wb->nr, &work->seen))
if (!test_bit(wb->nr, &work->seen))
continue;
clear_bit(wb->nr, &work->seen);
ret = work;
break;