K 10
svn:author
V 3
mav
K 8
svn:date
V 27
2020-02-04T15:53:51.961296Z
K 7
svn:log
V 677
Few microoptimizations to dbuf layer.

Move db_link into the same cache line as db_blkid and db_level.
It allows significantly reduce avl_add() time in dbuf_create() on
systems with large RAM and huge number of dbufs per dnode.

Avoid few accesses to dbuf_caches[].size, which is highly congested
under high IOPS and never stays in cache for a long time.  Use local
value we are receiving from zfs_refcount_add_many() any way.

Remove cache_size_bytes_max bump from dbuf_evict_one().  I don't see
a point to do it on dbuf eviction after we done it on insertion in
dbuf_rele_and_unlock().

Reviewed by:	mahrens, Brian Behlendorf
MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.

END