- Avoid atomic_add() when updating as_lower_bound/as_upper_bound.
Previous code was excessively strong on 64bit systems while not
strong enough on 32bit ones. Instead introduce and use real
atomic_load() and atomic_store() operations, just an assignments
on 64bit machines, but using proper atomics on 32bit ones to avoid
torn reads/writes.
- Reduce number of buckets on large systems. Extra buckets not as
much improve add speed, as hurt reads. Unlike wmsum for aggsum
reads are still important.
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#12145
This replaces the generic libspl atomic.c atomics implementation
with one based on builtin gcc atomics. This functionality was added
as an experimental feature in gcc 4.4. Today even CentOS 7 ships
with gcc 4.8 as the default compiler we can make this the default.
Furthermore, the builtin atomics are as good or better than our
hand-rolled implementation so it's reasonable to drop that custom code.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes#11904
