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Alexander Motin
a41ef36858
Before this change DDT lock was taken 4 times per written block, and as effectively a pool-wide lock it can be highly congested. This change introduces a new per-entry dde_io_lock, protecting some fields during I/O ready and done stages, so that we don't need the global lock there. According to my write tests on 64-thread system with 4KB blocks this significantly reduce the global lock contention, reducing CPU usage from 100% to expected ~80%, and increasing write throughput by 10%. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Rob Norris <robn@despairlabs.com> Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com> Closes #17960