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(),
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.
Updated by Electric Monk almost 3 years ago
- % Done changed from 0 to 100
- Status changed from New to Closed
commit 7588687e6ba67c47bf7c9805086dec4a97fcac7b Author: Matthew Ahrens <email@example.com> Date: 2016-11-30T20:51:54.000Z 7606 dmu_objset_find_dp() takes a long time while importing pool Reviewed by: Steve Gonczi <firstname.lastname@example.org> Reviewed by: George Wilson <email@example.com> Reviewed by: Prashanth Sreenivasa <firstname.lastname@example.org> Approved by: Gordon Ross <email@example.com>