ZFS send should use spill block prefetched from send_reader_thread #16701
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Not sure why tests are showing failure even though the test results seems mostly fine. |
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Crashed on assertion: |
Hmm... Edit: Ok, I think it's because we turn off zfs_send_unmodified_spill_blocks |
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Updated to prefetch also unmodified spill block in send_reader_thread. |
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The CI results are looking much better. @tuxoko if you rebase on the latest master it should resolve the Fedora 41 failure. |
amotin
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Nov 5, 2024
Currently, even though send_reader_thread prefetches spill block, do_dump() will not use it and issues its own blocking arc_read. This causes significant performance degradation when sending datasets with lots of spill blocks. For unmodified spill blocks, we also create send_range struct for them in send_reader_thread and issue prefetches for them. We piggyback them on the dnode send_range instead of enqueueing them so we don't break send_range_after check. Signed-off-by: Chunwei Chen <[email protected]>
amotin
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Nov 6, 2024
behlendorf
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Nov 6, 2024
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Status: Accepted
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Nov 6, 2024
Currently, even though send_reader_thread prefetches spill block, do_dump() will not use it and issues its own blocking arc_read. This causes significant performance degradation when sending datasets with lots of spill blocks. For unmodified spill blocks, we also create send_range struct for them in send_reader_thread and issue prefetches for them. We piggyback them on the dnode send_range instead of enqueueing them so we don't break send_range_after check. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Alexander Motin <[email protected]> Signed-off-by: Chunwei Chen <[email protected]> Co-authored-by: david.chen <[email protected]> Closes openzfs#16701
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Motivation and Context
Currently, even though send_reader_thread prefetches spill block, do_dump() will not use it and issues its own blocking arc_read. This may cause significant performance degradation when sending datasets with lots of spill blocks.
For unmodified spill blocks, we also create send_range struct for them in send_reader_thread and issue prefetches for them. We piggyback them on the dnode send_range instead of enqueueing them so we don't break send_range_after check.
On one of our setup, we see at least 5x difference during affected areas.
Description
How Has This Been Tested?
Manual send/recv on dataset with spill block.
Manual raw send/recv on encrypted dataset with spill block.
Types of changes
Checklist:
Signed-off-by.