Alexander Motin 645b833079 Improve write issue taskqs utilization ... - Reduce number of allocators on small system down to one per 4 CPU cores, keeping maximum at 4 on 16+ core systems. Small systems should not have the lock contention multiple allocators supposed to solve, while having several metaslabs open and modified each TXG is not free. - Reduce number of write issue taskqs down to one per 16 CPU cores and an integer fraction of number of allocators. On mid- sized systems, where multiple allocators already make sense, too many write issue taskqs may reduce write speed on single-file workloads, since single file is handled by only one taskq to reduce fragmentation. On large systems, that can actually benefit from many taskq's better IOPS, the bottleneck is less important, since in worst case there will be at least 16 cores to handle it. - Distribute dnodes between allocators (and taskqs) in a round- robin fashion instead of relying on sync taskqs to be balanced. The last is not guarantied and may depend on scheduling. - Remove io_wr_iss_tq from struct zio. io_allocator is enough. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored by: iXsystems, Inc. Closes #16130		2024-05-01 11:07:20 -07:00
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spl.4	Linux: Cleanup taskq threads spawn/exit	2024-02-13 11:15:16 -08:00
zfs.4	Improve write issue taskqs utilization	2024-05-01 11:07:20 -07:00