zfs/include/os/freebsd
Alexander Motin 85c43508f3 Introduce write-mostly sums
wmsum counters are a reduced version of aggsum counters, optimized for
write-mostly scenarios.  They do not provide optimized read functions,
but instead allow much cheaper add function.  The primary usage is
infrequently read statistic counters, not requiring exact precision.

The Linux implementation is directly mapped into percpu_counter KPI.
The FreeBSD implementation is directly mapped into counter(9) KPI.
In user-space due to lack of better implementation mapped to aggsum.

Unfortunately neither Linux percpu_counter nor FreeBSD counter(9)
provide sufficient functionality to completelly replace aggsum, so
it still remains to be used for several hot counters.

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored-By: iXsystems, Inc.
Closes #12114
2021-06-09 13:05:34 -07:00
..
linux FreeBSD: make adjustments for the standalone environment 2020-10-13 21:05:49 -07:00
spl Introduce write-mostly sums 2021-06-09 13:05:34 -07:00
zfs FreeBSD: add support for lockless symlink lookup 2021-04-14 13:23:08 -07:00
Makefile.am Add FreeBSD support to OpenZFS 2020-04-14 11:36:28 -07:00