illumos/illumos-gate@0d8fa8f8eb0d8fa8f8ebhttps://www.illumos.org/issues/6902
pjd has authored and commited a patch in Jan 21, 2012 that substanially speeds
up zfs snapshot listing if requesting only the name property and sorting by
name.
In this special case, the snapshot properties do not need to be loaded. This
code has been adopted by zfsonlinux on May 29, 2012.
Commit message from pjd:
Dramatically optimize listing snapshots when user requests only
snapshot
names and wants to sort them by name, ie. when executes:
1. 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:
1. time zfs list -t snapshot -o name -s name > /dev/null
cold cache: 525s
warm cache: 218s
after:
1. time zfs list -t snapshot -o name -s name > /dev/null
cold cache: 1.7s
warm cache: 1.1s
References:
http://svnweb.freebsd.org/base?view=revision&revision=230438https://github.com/freebsd/freebsd/commit/8e3e9863https://github.com/zfsonlinux/zfs/commit/0cee2406
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Pawel Dawidek <pjd@freebsd.org>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Garrett D'Amore <garrett@damore.org>
Author: Martin Matuska <martin@matuska.org>
73f0e3e3e5