Subject: Re: [PATCH v4 net-next 1/5] ethtool: Add support for configuring tx_push_buf_len

From: Jakub Kicinski <[email-masked]>
Date: Mon, 13 Mar 2023 12:09:42 -0700

On Sun, 12 Mar 2023 14:41:39 +0200 Gal Pressman wrote:
> On 10/03/2023 8:53, Jakub Kicinski wrote:
> > On Thu, 9 Mar 2023 19:15:43 +0200 Gal Pressman wrote:  
> >> I know Jakub prefers the new parameter, but the description of this
> >> still sounds extremely similar to TX copybreak to me..
> >> TX copybreak was traditionally used to copy packets to preallocated DMA
> >> buffers, but this could be implemented as copying the packet to the
> >> (preallocated) WQE's inline part. That usually means DMA memory, but
> >> could also be device memory in this ENA LLQ case.
> >>
> >> Are we drawing a line that TX copybreak is the threshold for DMA memory
> >> and tx_push_buf_len is the threshold for device memory?  
> > 
> > Pretty much, yes. Not an amazing distinction but since TX copybreak can
> > already mean two different things (inline or DMA buf) I'd err on 
> > the side of not overloading it with another one.   
> 
> Can we document that please?

Shay, could you add a paragraph in the docs regarding copybreak in v5?