4c925936e3
Traversal code, traverse_visitbp() does visit blocks recursively. Indirect (Non L0) Block of size 128k could contain, 1024 block pointers of 128 bytes. In case of full traverse OR incremental traverse, where all blocks were modified, it could traverse large number of blocks pointed by indirect. Traversal code does issue prefetch of blocks traversed below indirect. This could result into large number of async reads queued on vdev queue. So, account for prefetch issued for blocks pointed by indirect and limit max prefetch in one go. Module Param: zfs_traverse_indirect_prefetch_limit: Limit of prefetch while traversing an indirect block. Local counters: prefetched: Local counter to account for number prefetch done. pidx: Index for which next prefetch to be issued. ptidx: Index at which next prefetch to be triggered. Keep "ptidx" somewhere in the middle of blocks prefetched, so that blocks prefetch read gets the enough time window before their demand read is issued. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Signed-off-by: Jitendra Patidar <jitendra.patidar@nutanix.com> Closes #11802 Closes #11803 |
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