Re: [PATCH RESEND] virtio-net: support setting coalescing params for multiple vqs

[Jason Wang <jasowang@redhat.com>]

On Wed, Dec 20, 2023 at 10:40âPM Heng Qi <hengqi@linux.alibaba.com> wrote:
>
> Currently, when each time the driver attempts to update the coalescing parameters
> for a vq, it needs to kick the device and wait for the ctrlq response to return.
>
> If a command can only update one vq parameters, when the parameters are updated
> frequently (such as netdim), ctrlq on the device is kicked frequently, which will
> increase the device CPU scheduling overhead, and the number and overhead of device
> DMA will also increase.
>
> Merging multiple vq updated parameters into one command can effectively reduce
> the number of kick devices and device DMA times.
>
> Test results show that this greatly improves the efficiency of the ctrlq in
> responding to multiple vq coalescing parameter updates issued by the driver.

So netdim is per virtqueue, to make use of this, you need to batch the
netdim requests first. And if you do that, you can batch the commands
as well. Then you get one kick for sevreal coal requests?

Or are you saying you run out of ctrl vq?

Thanks