Alexander Motin a41ef36858 DDT: Reduce global DDT lock scope during writes
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
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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS is released under a CDDL license. For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported Linux kernel versions.
  • Supported FreeBSD versions are any supported branches and releases starting from 13.0-RELEASE.
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