netdev - Re: [net-next PATCH 0/2] Add ethtool support for completion event size

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Date:   Fri, 18 Feb 2022 11:07:11 +0530
From:   sundeep subbaraya <sundeep.lkml@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Subbaraya Sundeep <sbhatta@...vell.com>,
        David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        hariprasad <hkelam@...vell.com>,
        Geetha sowjanya <gakula@...vell.com>,
        Sunil Kovvuri Goutham <sgoutham@...vell.com>
Subject: Re: [net-next PATCH 0/2] Add ethtool support for completion event size

Hi Jakub,

On Thu, Feb 17, 2022 at 10:31 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Thu, 17 Feb 2022 20:19:04 +0530 Subbaraya Sundeep wrote:
> > After a packet is sent or received by NIC then NIC posts
> > a completion event which consists of transmission status
> > (like send success or error) and received status(like
> > pointers to packet fragments). These completion events may
> > also use a ring similar to rx and tx rings. This patchset
> > introduces ce-size ethtool parameter to modify the size
> > of the completion event if NIC hardware has that capability.
> > A bigger completion event can have more receive buffer pointers
> > inturn NIC can transfer a bigger frame from wire as long as
> > hardware(MAC) receive frame size limit is not exceeded.
> >
> > Patch 1 adds support setting/getting ce-size via
> > ethtool -G and ethtool -g.
> >
> > Patch 2 includes octeontx2 driver changes to use
> > completion event size set from ethtool -G.
>
> Please add an explanation to ethtool-netlink.rst so people can
> understand what the semantics are.
>
Sure

> I think we may want to rename CE -> CQE, we used cqe for IRQ config.
>
I used CE because not to be confused with CQE mode in coalesce. I will
change to CQE

> Does changing the CQE size also change the size of the completion ring?
> Or does it only control aggregation / writeback size?

In our case we change the completion ring size too.

Thanks,
Sundeep