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From: Alex Williamson <alex.williamson@redhat.com>
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Subject: Re: [Qemu-devel] =?utf-8?q?About_virtio_device_hotplug_in_Q35!_?=
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To: Bob Chen <a175818323@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel@redhat.com>, =?UTF-8?B?6ZmI5Y2a?= <chenbo02@meituan.com>, qemu-devel@nongnu.org

On Wed, 30 Aug 2017 17:41:20 +0800
Bob Chen <a175818323@gmail.com> wrote:

> I think I have observed what you said...
> 
> The link speed on host remained 8GT/s until I finished running
> p2pBandwidthLatencyTest
> for the first time. Then it became 2.5GT/s...
> 
> 
> # lspci -s 09:00.0 -vvv
...
> LnkSta: Speed 8GT/s, Width x16, TrErr- Train- SlotClk+ DLActive- BWMgmt-

So long as the device renegotiates to 8GT/s under load rather than
getting stuck at 2.5GT/s, I think this is the expected behavior.  This
is a power saving measure by the driver.  Thanks,

Alex