netdev - Re: [PATCH net-next 1/3] ethtool: add tx aggregation parameters

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Message-ID: <CAGRyCJF0v8M3Ebd3tSnLpWeB6K5pOtWvbhd1tzOnTE8ZHs4r0w@mail.gmail.com>
Date:   Fri, 11 Nov 2022 22:51:37 +0100
From:   Daniele Palmas <dnlplm@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     David Miller <davem@...emloft.net>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Subash Abhinov Kasiviswanathan <quic_subashab@...cinc.com>,
        Sean Tranchetti <quic_stranche@...cinc.com>,
        Jonathan Corbet <corbet@....net>,
        Bjørn Mork <bjorn@...k.no>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        netdev@...r.kernel.org
Subject: Re: [PATCH net-next 1/3] ethtool: add tx aggregation parameters

Hello Jakub,

Il giorno ven 11 nov 2022 alle ore 18:07 Jakub Kicinski
<kuba@...nel.org> ha scritto:
>
> On Wed,  9 Nov 2022 19:02:47 +0100 Daniele Palmas wrote:
> > Add the following ethtool tx aggregation parameters:
> >
> > ETHTOOL_A_COALESCE_TX_MAX_AGGR_SIZE
> > Maximum size of an aggregated block of frames in tx.
>
> perhaps s/size/bytes/ ? Or just mention bytes in the doc? I think it's
> the first argument in coalescing expressed in bytes, so to avoid
> confusion we should state that clearly.

Right, better to have the word bytes to make it clear.

>
> > ETHTOOL_A_COALESCE_TX_MAX_AGGR_FRAMES
> > Maximum number of frames that can be aggregated into a block.
> >
> > ETHTOOL_A_COALESCE_TX_USECS_AGGR_TIME
> > Time in usecs after the first packet arrival in an aggregated
> > block for the block to be sent.
>
> Can we add this info to the ethtool-netlink.rst doc?
>
> Can we also add a couple of sentences describing what aggregation is?
> Something about copying the packets into a contiguous buffer to submit
> as one large IO operation, usually found on USB adapters?
>
> People with very different device needs will read this and may pattern
> match the parameters to something completely different like just
> delaying ringing the doorbell. So even if things seem obvious they are
> worth documenting.
>

Sure, I'll take care of documenting this better.

> > diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
> > index d578b8bcd8a4..a6f115867648 100644
> > --- a/Documentation/networking/ethtool-netlink.rst
> > +++ b/Documentation/networking/ethtool-netlink.rst
> > @@ -1001,6 +1001,9 @@ Kernel response contents:
> >    ``ETHTOOL_A_COALESCE_RATE_SAMPLE_INTERVAL``  u32     rate sampling interval
> >    ``ETHTOOL_A_COALESCE_USE_CQE_TX``            bool    timer reset mode, Tx
> >    ``ETHTOOL_A_COALESCE_USE_CQE_RX``            bool    timer reset mode, Rx
> > +  ``ETHTOOL_A_COALESCE_TX_MAX_AGGR_SIZE``      u32     max aggr packets size, Tx
> > +  ``ETHTOOL_A_COALESCE_TX_MAX_AGGR_FRAMES``    u32     max aggr packets, Tx
> > +  ``ETHTOOL_A_COALESCE_TX_USECS_AGGR_TIME``    u32     time (us), aggr pkts, Tx
>
> nit: perhaps move _aggr before the specifics? e.g.
>
>  ETHTOOL_A_COALESCE_TX_AGGR_MAX_SIZE
>  ETHTOOL_A_COALESCE_TX_AGGR_USECS_TIME
>

Ack.

> FWIW I find that the easiest way to do whole-sale renames in a series
> is to generate the patches as .patch files, run sed on those, and apply
> them back on a fresh branch. Rebasing is a PITA with renames.
>

Thanks for the advice.

> Other then these nit picks - looks very reasonable :)

Thanks for the review!

Regards,
Daniele