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Avoid vq_lock drop in vdev_queue_aggregate(). #12297

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merged 1 commit into from
Aug 17, 2021

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@amotin amotin commented Jun 29, 2021

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.

How Has This Been Tested?

On 80-thread FreeBSD system doing random 4KB ZVOLs writes profiler shows reduction vq_lock spinning time by 15%.

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Performance enhancement (non-breaking change which improves efficiency)
  • Code cleanup (non-breaking change which makes code smaller or more readable)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
  • Documentation (a change to man pages or other documentation)

Checklist:

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.

Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored-By: iXsystems, Inc.
@amotin amotin added Type: Performance Performance improvement or performance problem Status: Code Review Needed Ready for review and testing labels Jun 29, 2021
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@amotin, this is awesome! I have actually been looking at the vq_lock myself for the O_DIRECT work PR #10018. I have been working on reducing lock contention as well on the vq_lock.

@behlendorf behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Jul 26, 2021
@mmaybee mmaybee merged commit 7f9d9e6 into openzfs:master Aug 17, 2021
@amotin amotin deleted the vq_lock_reenter branch August 24, 2021 20:17
behlendorf pushed a commit to behlendorf/zfs that referenced this pull request Aug 24, 2021
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>
Closes openzfs#12297
behlendorf pushed a commit that referenced this pull request Aug 31, 2021
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>
Closes #12297
tonyhutter pushed a commit to tonyhutter/zfs that referenced this pull request Sep 15, 2021
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>
Closes openzfs#12297
rincebrain pushed a commit to rincebrain/zfs that referenced this pull request Sep 22, 2021
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
datacore-rm pushed a commit to DataCoreSoftware/openzfs that referenced this pull request Apr 1, 2022
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
datacore-rm pushed a commit to DataCoreSoftware/openzfs that referenced this pull request Apr 1, 2022
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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4 participants