On Tue, Oct 26, 2010 at 09:36:26AM -0700, Sage Weil wrote: > On Tue, 26 Oct 2010, liubo wrote: > > > > Since wake_up() itself provides a implied wmb, and a wq active check, > > it is better to drop "if (wq)" in __btrfs_end_transaction(). > > I see. It could also be > > smb_mb(); > if (wq) > wake_up(); > > but just calling wake_up() unconditionally is simpler, and fewer barriers > in the wake_up case. I'm not attached to the if (wq); I just kept it > because it was there already. wake_up() provides an implied barrier because it takes the lock. I usually do the smp_mb() + if (wq) dance when I'm working on a relatively hot waitqueue. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
