freebsd-dev/module
George Melikov 1149ba6478 OpenZFS 7606 - dmu_objset_find_dp() takes a long time while importing pool
When importing a pool with a large number of filesystems within the same
parent filesystem, we see that dmu_objset_find_dp() takes a long time.
It is called from 3 places: spa_check_logs(), spa_ld_claim_log_blocks(),
and spa_load_verify().

There are several ways to improve performance here:

    1. We don't really need to do spa_check_logs() or
       spa_ld_claim_log_blocks() if the pool was closed cleanly.

    2. spa_load_verify() uses dmu_objset_find_dp() to check that no
       datasets have too long of names.

    3. dmu_objset_find_dp() is slow because it's doing
       zap_value_search() (which is O(N sibling datasets)) to determine
       the name of each dsl_dir when it's opened. In this case we
       actually know the name when we are opening it, so we can provide
       it and avoid the lookup.

This change implements fix #3 from the above list; i.e. make
dmu_objset_find_dp() provide the name of the dataset so that we don't
have to search for it.

Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Steve Gonczi <steve.gonczi@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Prashanth Sreenivasa <prashksp@gmail.com>
Reviewed-by: David Quigley <david.quigley@intel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: George Melikov <mail@gmelikov.ru>

OpenZFS-issue: https://www.illumos.org/issues/7606
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/cac6bab
Closes #5662
2017-01-26 12:46:02 -08:00
..
avl Fix uninitialized variable in avl_add() 2016-07-25 14:21:34 -07:00
icp codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
nvpair Fix spelling 2017-01-03 11:31:18 -06:00
unicode codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
zcommon OpenZFS 7304 - zfs filesystem/snapshot counts should be read-only 2017-01-23 10:17:35 -08:00
zfs OpenZFS 7606 - dmu_objset_find_dp() takes a long time while importing pool 2017-01-26 12:46:02 -08:00
zpios codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
.gitignore module/.gitignore: Add *.dwo (#4580) 2016-05-02 09:07:04 -07:00
Makefile.in module/Makefile.in: use relative cp 2017-01-13 15:18:34 -08:00