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Re: [Qemu-devel] [PATCH 0/5] vhost-scsi: Add support for host virtualize
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 0/5] vhost-scsi: Add support for host virtualized target |
Date: |
Fri, 14 Sep 2012 10:21:05 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120828 Thunderbird/15.0 |
Il 13/09/2012 22:12, Nicholas A. Bellinger ha scritto:
>> > Are you still seeing the performance degradation discussed in the thread
>> >
>> > "vhost-scsi port to v1.1.0 + MSI-X performance regression"
>> >
> So the performance regression reported here with QEMU v1.2-rc +
> virtio-scsi ended up being related to virtio interrupts being delivered
> across multiple CPUs.
>
> After explicitly setting the IRQ affinity of the virtio0-request MSI-X
> vector to a specific CPU, the small block (4k) mixed random I/O
> performance jumped back up to the expected ~100K IOPs for a single LUN.
Have you tried setting rq_affinity to 2? Benchmarking this against
multiqueue virtio-scsi is on my todo list.
Paolo
> FYI, I just tried this again with the most recent QEMU v1.2.50 (v1.3-rc)
> code, and both cases appear to be performing as expected once again
> regardless of the explicit IRQ affinity setting.
[Qemu-devel] [PATCH 5/5] virtio-scsi: Set max_target=0 during vhost-scsi operation, Nicholas A. Bellinger, 2012/09/07
Re: [Qemu-devel] [PATCH 0/5] vhost-scsi: Add support for host virtualized target, Asias He, 2012/09/11