If the fields to be listed and sorted by are constrained
to those populated by dsl_dataset_fast_stat(), then
zfs list is much faster, as it does not need to open each
objset and reads its properties.
A previous optimization by Pawel Dawidek
(0cee24064a) took advantage
of this to make listing snapshot names sorted only by name
much faster.
However, it was limited to `-o name -s name`, this work
extends this optimization to work with:
- name
- guid
- createtxg
- numclones
- inconsistent
- redacted
- origin
and could be further extended to any other properties
supported by dsl_dataset_fast_stat() or similar, that do
not require extra locking or reading from disk.
Reviewed-by: Mark Maybee <mark.maybee@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pawel Jakub Dawidek <pawel@dawidek.net>
Signed-off-by: Allan Jude <allan@klarasystems.com>
Closes#11080
FreeBSD #xxx: Dramatically optimize listing snapshots when user
requests only snapshot names and wants to sort them by name, ie.
when executes:
# zfs list -t snapshot -o name -s name
Because only name is needed we don't have to read all snapshot
properties.
Below you can find how long does it take to list 34509 snapshots
from a single disk pool before and after this change with cold and
warm cache:
before:
# time zfs list -t snapshot -o name -s name > /dev/null
cold cache: 525s
warm cache: 218s
after:
# time zfs list -t snapshot -o name -s name > /dev/null
cold cache: 1.7s
warm cache: 1.1s
NOTE: This patch only appears in FreeBSD. If/when Illumos picks up
the change we may want to drop this patch and adopt their version.
However, for now this addresses a real issue.
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #450
