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  1. RHEL
  2. RHEL-7416

[libvirt] RFE: Per-virtqueue IOThread assignment for virtio-blk

    • sst_virtualization_storage
    • ssg_virtualization
    • 20
    • 26
    • 3
    • QE ack, Dev ack
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    • Yes
    • Red Hat Enterprise Linux
    • None
    • Enhancement
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      .Improved I/O performance for `virtio-blk` disk devices

      With this update, you can configure a separate IOThread for each virtqueue in a `virtio-blk` disk device. This configuration improves performance for virtual machines with multiple CPUs during intensive I/O workloads.
      Show
      .Improved I/O performance for `virtio-blk` disk devices With this update, you can configure a separate IOThread for each virtqueue in a `virtio-blk` disk device. This configuration improves performance for virtual machines with multiple CPUs during intensive I/O workloads.
    • Done
    • Unspecified
    • 10.0.0
    • None

      Work is underway to add per-virtqueue IOThread mapping to QEMU's virtio-blk and virtio-scsi devices.

      Currently each device instance can be associated with just one IOThread where all virtqueues are processed. This is known to be a bottleneck and prevents true multi-queue operation because all I/O requests are funneled through a single IOThread on the host.

      The new multi-queue support in QEMU will allow individual virtqueues to be mapped to an IOThread. It is likely that most users will wish to spread virtqueues round-robin across a set of IOThreads.

      New domain XML syntax is necessary to expose this feature once it becomes available in QEMU.

      I am filing this BZ now so there is time to discuss the feature and so that libvirt support can be developed in parallel to QEMU.

            pkrempa@redhat.com Peter Krempa
            stefanha@redhat.com stefanha@redhat.com
            Dan Zheng
            Peter Krempa Peter Krempa
            Fangge Jin Fangge Jin
            Daniel Vozenilek Daniel Vozenilek
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