Hi Sage, Are you optimistic about the release of Bluestore ? 2016-02-22 13:01 GMT+01:00 Sage Weil <sage@xxxxxxxxxxxx>: > On Fri, 19 Feb 2016, Dave Chinner wrote: >> On Tue, Feb 16, 2016 at 09:39:28AM +0100, David Casier wrote: >> > "With this model, filestore rearrange the tree very >> > frequently : + 40 I/O every 32 objects link/unlink." >> > It is the consequence of parameters : >> > filestore_merge_threshold = 2 >> > filestore_split_multiple = 1 >> > >> > Not of ext4 customization. >> >> It's a function of the directory structure you are using to work >> around the scalability deficiencies of the ext4 directory structure. >> i.e. the root cause is that you are working around an ext4 problem. > > If only it were just that :(. The other problem is that we need in-order > enumeration of files/objects (with a particular sort order we define) and > POSIX doesn't give us that. Small directories let us read the whole thing > and sort in memory. > > If there is a 'good' directory size that tends to have a small/minimal > number of IOs for listing all files it may make sense to change the > defaults (picked semi-randomly several years back), but beyond that there > isn't much to do here except wait for the replacement for this whole > module that doesn't try to map our namespace onto POSIX's. > > Optimizations to any of this FileStore code will see limited mileage since > it'll be deprecated shortly anyway... > > sage -- ________________________________________________________ Cordialement, David CASIER 3B Rue Taylor, CS20004 75481 PARIS Cedex 10 Paris Ligne directe: 01 75 98 53 85 Email: david.casier@xxxxxxxx ________________________________________________________ -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
