On Mon, Aug 21, 2017 at 12:14:16PM -0700, Liu Bo wrote: > On Mon, Aug 21, 2017 at 01:48:01PM -0400, Josef Bacik wrote: > > On Fri, Aug 18, 2017 at 11:42:07AM -0600, Liu Bo wrote: > > > We have started plug in btrfs_write_and_wait_marked_extents() but the > > > generated IOs actually go to device's schedule IO list where the work > > > is doing in another task, thus the started plug doesn't make any > > > sense. > > > > > > And since we wait for IOs immediately after writing meta blocks, it's > > > the same case as writing log tree, doing sync submit can merge more > > > IOs. > > > > > > > We're plugging when we do the per-device scheduled IO right? > > Yes, we are. > > > So we aren't > > really gaining anything by it being async. Also we do a lot of work > > between the > > time that we start writing the marked extents for the tree-log and when we > > actually wait for them, so we really don't want to do a synchronous write > > out in > > that case. > > Hmm, we've always been doing sync write for meta blocks of log > tree/log root tree, because of EXTENT_BIO_TREE_LOG (introduced in > commit de0022b9da616b95ea5b41eab32da825b0b5150f), and the commit log > claimed about 15% performance gaining in O_SYNC workloads (maybe we > need to re-evaluate it?). > > > Instead move the sync_writers into write_and_wait_marked_extents. > > Thanks, > > I'm OK with the change, but if sync write benefits both transaction > commit case and log tree case, we can unify them to %sync_writers > instead of a bio_flag. >
Sigh you're right, I forgot about all of that. Just delete the magic bio flags stuff and then this is fine. Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
