From: Josh Durgin <josh.durgin@inktank.com>
To: Alex Elder <elder@inktank.com>
Cc: ceph-devel@vger.kernel.org
Subject: Re: [PATCH 0/4] rbd: get rid of the snapshot list
Date: Tue, 30 Apr 2013 18:32:41 -0700 [thread overview]
Message-ID: <518070B9.3060601@inktank.com> (raw)
In-Reply-To: <51806C07.60007@inktank.com>
On 04/30/2013 06:12 PM, Alex Elder wrote:
> On that, the only thing inefficient is looking up the
> snapshot id given its name. It is so inefficient it
> might be worth offering an op that does that for us,
> because as it is we have to do a sequential search
> to find out a snapshot's name. (Maybe it's not that
> important to track the name for parent snapshots but
> users might be interested.)
That would be more efficient, but I don't think it's worth going that
far. The client would need a way to work with current osds too, and
it's not that much data - it's mainly the extra latency from fetching
it that would be the problem. Iterating over 1000 snapshot names in
memory is much faster, and only done when mapping for the kernel.
Userspace fetches all the snapshot metadata in one operation, and
indexes it by name in memory (which is useful since all the librbd
calls relating to snapshots deal with names).
prev parent reply other threads:[~2013-05-01 1:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-30 12:41 [PATCH 0/4] rbd: get rid of the snapshot list Alex Elder
2013-04-30 12:42 ` [PATCH 1/4] rbd: look up snapshot name in names buffer Alex Elder
2013-04-30 12:42 ` [PATCH 2/4] rbd: use snap_id not index to look up snap info Alex Elder
2013-04-30 12:42 ` [PATCH 3/4] rbd: define rbd_snap_size() and rbd_snap_features() Alex Elder
2013-04-30 12:43 ` [PATCH 4/4] rbd: kill off the snapshot list Alex Elder
2013-05-01 0:57 ` [PATCH 0/4] rbd: get rid of " Josh Durgin
2013-05-01 1:12 ` Alex Elder
2013-05-01 1:16 ` Alex Elder
2013-05-01 1:32 ` Josh Durgin [this message]
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