在 2023/9/25 上午10:29, Jason Wang 写道:

On Fri, Sep 22, 2023 at 3:58 PM Heng Qi [off-list ref] wrote:

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在 2023/9/22 下午3:32, Jason Wang 写道:

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On Fri, Sep 22, 2023 at 1:02 PM Heng Qi [off-list ref] wrote:

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在 2023/9/22 下午12:29, Jason Wang 写道:

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On Tue, Sep 19, 2023 at 3:49 PM Heng Qi [off-list ref] wrote:

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According to the definition of virtqueue coalescing spec[1]:

     Upon disabling and re-enabling a transmit virtqueue, the device MUST set
     the coalescing parameters of the virtqueue to those configured through the
     VIRTIO_NET_CTRL_NOTF_COAL_TX_SET command, or, if the driver did not set
     any TX coalescing parameters, to 0.

     Upon disabling and re-enabling a receive virtqueue, the device MUST set
     the coalescing parameters of the virtqueue to those configured through the
     VIRTIO_NET_CTRL_NOTF_COAL_RX_SET command, or, if the driver did not set
     any RX coalescing parameters, to 0.

We need to add this setting for vq resize (ethtool -G) where vq_reset happens.

[1] https://lists.oasis-open.org/archives/virtio-dev/202303/msg00415.html

Fixes: 394bd87764b6 ("virtio_net: support per queue interrupt coalesce command")

I'm not sure this is a real fix as spec allows it to go zero?

The spec says that if the user has configured interrupt coalescing
parameters,
parameters need to be restored after vq_reset, otherwise set to 0.
vi->intr_coal_tx and vi->intr_coal_rx always save the newest global
parameters,
regardless of whether the command is sent or not. So I think we need
this patch
it complies with the specification requirements.

How can we make sure the old coalescing parameters still make sense
for the new ring size?

I'm not sure, ringsize has a wider range of changes. Maybe we should
only keep coalescing
parameters in cases where only vq_reset occurs (no ring size change
involved)?

Probably but do we actually have a user other than resize now?

Not yet. What I mean is if there is one in the future, for example in 
xdp's processing etc.,
we can reserve parameters for it.

Thanks

Thanks

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Thanks!

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