(still away at the choir festival for another week... but I got online and downloaded a bunch of emails)
On Fri, Jan 18, 2008 at 08:46:23AM -0500, Chris mason wrote: > On Thursday 17 January 2008, Bron Gondwana wrote: > > On Tue, Jan 15, 2008 at 10:53:29AM -0500, Chris Mason wrote: > > > Btrfs is still in an early alpha state, and the disk format is not > > > finalized. v0.10 introduces a new disk format, and is not compatible with > > > v0.9. > > > > > > The core of this release is explicit back references for all metadata > > > blocks, data extents, and directory items. These are a crucial building > > > block for future features such as online fsck and migration between > > > devices. The back references are verified during deletes, and the extent > > > back references are checked by the existing offline fsck tool. > > > > Just as a random datapoint, Maildir access (read only) via mutt feels > > much more sluggish than on 0.5, which is the last release of btrfs I > > played with. The Maildirs have just been created by using rsync to > > copy them from my usual reiserfs partition. It's still massively > > slower than reiserfs for the Maildir access pattern that I have. > > With atimes on or off? What is the maildir access pattern? The backrefs > make > it possible to do a bunch of interesting readdir optimizations. That's a point, mounted btrfs as "default" but reiserfs is noatime,nodiratime. I'll go add a noatime to the btrfs mount options and try that. Access pattern is whatever mutt is doing - presumably getting a directory listing and then reading the start of each file it hasn't got in its cache yet. > You'll also bang into the locking if you have a number of processes doing > cold-cache reads at the same time. Generally not - it's either just the single mutt process or a mutt process and a (multi-threaded) python offlineimap process - but I always run them by hand, and only when I'm online (obviously). Bron. _______________________________________________ Btrfs-devel mailing list [email protected] http://oss.oracle.com/mailman/listinfo/btrfs-devel
