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* More aggsum optimizationsAlexander Motin2021-06-091-3/+4
| | | | | | | | | | | | | | | | | | - 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 <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored-By: iXsystems, Inc. Closes #12145
* Reduce number of atomic_add() calls in aggsumAlexander Motin2020-02-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | Previous code used 4 atomics to do aggsum_flush_bucket() and 2 more to re-borrow after the flush. But since asc_borrowed and asc_delta are accessed only while holding asc_lock, it makes no any sense to modify as_lower_bound and as_upper_bound in multiple steps. Instead of that the new code uses only 2 atomics in all the cases, one per as_*_bound variable. I think even that is overkill, simple atomic store and load could be used here, since all modifications are done under the as_lock, but there are no such primitives in ZFS code now. While there, make borrow code consider previous borrow value, so that on mixed request patterns reduce chance of needing to borrow again if much larger request follows tiny one that needed borrow. Also reduce as_numbuckets from uint64_t to u_int. It makes no sense to use so large division operation on every aggsum_add(). Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Paul Dagnelie <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored-By: iXsystems, Inc. Closes #9930
* OpenZFS 8484 - Implement aggregate sum and use for arc countersPaul Dagnelie2018-06-061-0/+59
In pursuit of improving performance on multi-core systems, we should implements fanned out counters and use them to improve the performance of some of the arc statistics. These stats are updated extremely frequently, and can consume a significant amount of CPU time. Authored by: Paul Dagnelie <[email protected]> Reviewed by: Pavel Zakharov <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Approved by: Dan McDonald <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Ported-by: Paul Dagnelie <[email protected]> OpenZFS-issue: https://www.illumos.org/issues/8484 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7028a8b92b7 Issue #3752 Closes #7462