- With both pending and current AVL-trees being per-vdev and having
effectively identical comparison functions (pending tree compared
also birth time, but I don't believe it is possible for them to be
different for the same offset within one transaction group), it
makes no sense to move entries from one to another. Instead inline
dramatically simplified brt_entry_addref() into brt_pending_apply().
It no longer requires bv_lock, since there is nothing concurrent
to it at the time. And it does not need to search the tree for the
previous entries, since it is the same tree, we already have the
entry and we know it is unique.
- Put brt_vdev_lookup() and brt_vdev_addref() into different tree
traversals to avoid false positives in the first due to the second
entcount modifications. It saves dramatic amount of time when a
file cloned first time by not looking for non-existent ZAP entries.
- Remove avl_is_empty(bv_tree) check from brt_maybe_exists(). I
don't think it is needed, since by the time all added entries are
already accounted in bv_entcount. The extra check must be producing
too many false positives for no reason. Also we don't need bv_lock
there, since bv_entcount pointer must be table at this point, and
we don't care about false positive races here, while false negative
should be impossible, since all brt_vdev_addref() have already
completed by this point. This dramatically reduces lock contention
on massive deletes of cloned blocks. The only remaining one is
between multiple parallel free threads calling brt_entry_decref().
- Do not update ZAP if net change for a block over the TXG was 0.
In combination with above it makes file move between datasets as
cheap operation as originally intended if it fits into one TXG.
- Do not allocate vdevs on pool creation or import if it did not
have active block cloning. This allows to save a bit in few cases.
- While here, add proper error handling in brt_load() on pool
import instead of assertions.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored by: iXsystems, Inc.
Closes#16773
While block cloning operation from the beginning was made per-vdev,
before this change most of its data were protected by two pool-
wide locks. It created lots of lock contention in many workload.
This change makes most of block cloning data structures per-vdev,
which allows to lock them separately. The only pool-wide lock now
it spa_brt_lock, protecting array of per-vdev pointers and in most
cases taken as reader. Also this splits per-vdev locks into three
different ones: bv_pending_lock protects the AVL-tree of pending
operations in open context, bv_mos_entries_lock protects BRT ZAP
object from while being prefetched, and bv_lock protects the rest
of per-vdev context during TXG commit process. There should be
no functional difference aside of some optimizations.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Pawel Jakub Dawidek <pjd@FreeBSD.org>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored by: iXsystems, Inc.
Closes#16740
So that zdb (and others!) can get at the BRT on-disk structures.
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Kay Pedersen <mail@mkwg.de>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes#15541
