On Mon, Aug 1, 2011 at 4:26 PM, Bruce Guenter [off-list ref] wr=
ote:

On Thu, Jul 28, 2011 at 04:28:04PM -0400, Chris Mason wrote:

quoted

The slow performance is probably coming from reading in the metadata
associated with the snapshot extents. =C2=A0The new readahead extent=

ions from

quoted

Arne should help once we've adapted them to it. =C2=A0The easiest wa=

y to make

quoted

sure is to hit sysrq-w a few times while it is slow (or run a patche=

d

quoted

latencytop).

We shut down the rsync backups for now, and are waiting for the
snapshots to complete deletion so we can unmount the filesystem to
reboot (missing kernel options for latencytop). =C2=A0In the mean tim=

e I hit

SysRq-W quite a number of times, and nothing is showing up in kernel

The keystroke should be alt-sysrq-w.

messages. =C2=A0However, btrfs-cleaner and/or btrfs-transaction (some=

times

both, sometimes just one) have been running high in top, taking up al=

l

the CPU time.

--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" =
in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html