On Mon, Jul 19, 2010 at 07:27:05PM +0800, Chris Mason wrote: > On Wed, Jul 14, 2010 at 04:02:21PM +0800, Shaohua Li wrote: > > Add an ioctl to dump btrfs btree_inode's existing pages. Userspace collects > > such > > info and uses it to do metadata readahead. > > In your tests, how often is the mincore done on metadata? With cow > (especially with cow and atime), the metadata blocks are going to change > quite a lot. Meego uses relatime. The proposal is doing mincore in every boot. In my test, I delete several files and a dir, create a dir and several files, the hit rate is > 80%, which is already pretty good for boot. In userspace, we record some extra pages. For example, if mincore returns two pages 2 and 4, userspace will record pages 2-4, in total 3 pages, this will slightly increase hit rate too.
Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
