Giuseppe Di Natale 45d1abc74d Improved dnode allocation and dmu_hold_impl() (#6611) ... Refactor dmu_object_alloc_dnsize() and dnode_hold_impl() to simplify the code, fix errors introduced by commit dbeb879 (PR #6117) interacting badly with large dnodes, and improve performance. * When allocating a new dnode in dmu_object_alloc_dnsize(), update the percpu object ID for the core's metadnode chunk immediately. This eliminates most lock contention when taking the hold and creating the dnode. * Correct detection of the chunk boundary to work properly with large dnodes. * Separate the dmu_hold_impl() code for the FREE case from the code for the ALLOCATED case to make it easier to read. * Fully populate the dnode handle array immediately after reading a block of the metadnode from disk. Subsequently the dnode handle array provides enough information to determine which dnode slots are in use and which are free. * Add several kstats to allow the behavior of the code to be examined. * Verify dnode packing in large_dnode_008_pos.ksh. Since the test is purely creates, it should leave very few holes in the metadnode. * Add test large_dnode_009_pos.ksh, which performs concurrent creates and deletes, to complement existing test which does only creates. With the above fixes, there is very little contention in a test of about 200,000 racing dnode allocations produced by tests 'large_dnode_008_pos' and 'large_dnode_009_pos'. name type data dnode_hold_dbuf_hold 4 0 dnode_hold_dbuf_read 4 0 dnode_hold_alloc_hits 4 3804690 dnode_hold_alloc_misses 4 216 dnode_hold_alloc_interior 4 3 dnode_hold_alloc_lock_retry 4 0 dnode_hold_alloc_lock_misses 4 0 dnode_hold_alloc_type_none 4 0 dnode_hold_free_hits 4 203105 dnode_hold_free_misses 4 4 dnode_hold_free_lock_misses 4 0 dnode_hold_free_lock_retry 4 0 dnode_hold_free_overflow 4 0 dnode_hold_free_refcount 4 57 dnode_hold_free_txg 4 0 dnode_allocate 4 203154 dnode_reallocate 4 0 dnode_buf_evict 4 23918 dnode_alloc_next_chunk 4 4887 dnode_alloc_race 4 0 dnode_alloc_next_block 4 18 The performance is slightly improved for concurrent creates with 16+ threads, and unchanged for low thread counts. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Olaf Faaland <faaland1@llnl.gov>		2017-09-13 15:46:15 -07:00
..
.gitignore	Add .gitignore files to exclude build products	2010-01-08 11:35:17 -08:00
Makefile.am	Cleanup linking	2016-03-18 13:31:11 -07:00
zdb_il.c	DLPX-44812 integrate EP-220 large memory scalability	2016-11-29 14:34:27 -08:00
zdb.c	Improved dnode allocation and dmu_hold_impl() (#6611)	2017-09-13 15:46:15 -07:00