K 10 svn:author V 3 avg K 8 svn:date V 27 2017-04-14T18:08:50.653934Z K 7 svn:log V 1505 7606 dmu_objset_find_dp() takes a long time while importing pool illumos/illumos-gate@7588687e6ba67c47bf7c9805086dec4a97fcac7b https://github.com/illumos/illumos-gate/commit/7588687e6ba67c47bf7c9805086dec4a97fcac7b https://www.illumos.org/issues/7606 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. Reviewed by: Steve Gonczi Reviewed by: George Wilson Reviewed by: Prashanth Sreenivasa Approved by: Gordon Ross Author: Matthew Ahrens END