Virtualization - Jul 2021 - [Question] virtio-net: About napi_tx

Hi Willem and list,

The napi_tx of virtio_net is enabled by default by commit 31c03aef.

and the commit message mentioned:
     In the unlikely case of regression, we have landed a credible 
runtime
     solution. Ethtool can configure it with -C tx-frames [0|1] as of
     commit 0c465be183c7 ("virtio_net: ethtool tx napi
configuration").

I'd like to know more about "the unlikely case of regression".
Is it workloads related or bare metal hardware related?

Do you mind to explain some details?

Thanks,
Lin

On Tue, Jul 13, 2021 at 3:04 AM lma <lma at suse.de>
wrote:
>
> Hi Willem and list,
>
> The napi_tx of virtio_net is enabled by default by commit 31c03aef.
>
> and the commit message mentioned:
>      In the unlikely case of regression, we have landed a credible
> runtime
>      solution. Ethtool can configure it with -C tx-frames [0|1] as of
>      commit 0c465be183c7 ("virtio_net: ethtool tx napi
configuration").
>
> I'd like to know more about "the unlikely case of
regression".
> Is it workloads related or bare metal hardware related?
There are no specific known cases. This is a precaution if a user
discovers a regression.