merging the commits from upstream which reduces the lock contention in vdev_queue. #42
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This dramatically reduces the lock contention on systems with slower (non-TSC) timecounters. With TSC the difference is minimal, but since this lock is pretty congested, any improvement counts. Plus I don't see any reason to do it under the lock other than the latency of the lock itself, which this change actually reduces. Reviewed-by: Matthew Ahrens <mahrens@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored-By: iXsystems, Inc. Closes openzfs#12281
vq_lock is already too congested for two more operations per I/O. Instead of dropping and reacquiring it inside vdev_queue_aggregate() delegate the zio_vdev_io_bypass() and zio_execute() calls for parent I/Os to callers, that drop the lock any way to execute the new I/O. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Mark Maybee <mark.maybee@delphix.com> Reviewed-by: Brian Atkinson <batkinson@lanl.gov> Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored-By: iXsystems, Inc. Closes openzfs#12297
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merging the 2 commits from upstream which reduces the lock contention in vdev_queue.