On Wed, May 20, 2009 at 02:16:30PM +0200, Jens Axboe wrote: > It's a fine rule, I agree ;-) > > I'll take another look at this when splitting the sync paths. Btw, there has been quite a bit of work on the higher level sync code in the VFS tree, and I have some TODO list items for the lower level sync code. The most important one would be splitting data and metadata writeback. Currently __sync_single_inode first calls do_writepages to write back the data, then write_inode to potentially write the metadata and then finally filemap_fdatawait to wait for the inode to be completed. Now for one thing doing the data wait after the metadata writeout is wrong for all those filesystems performing some kind of metadata updates in the I/O completion handler, and e.g. XFS has to work around this by doing a wait by itself in it's write_inode handler. Second inodes are usually clustered together, so if a filesystem can issue multiple dirty inodes at the same time performance will be much better. So an optimal sync could would first issue data I/O for all inodes it wants to write back, then wait for the data I/O to finish and finally write out the inodes in big clusters. I'm not quite sure when we'll get to that, just making sure we don't work against this direction anywhere. And yeah, I really need to take a detailed look at the current incarnation of your patchset :) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
