netdev - Re: [PATCH net-next v4 0/3] add tx packets aggregation to ethtool and rmnet

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Date:   Sun, 15 Jan 2023 13:15:16 +0100
From:   Daniele Palmas <dnlplm@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Alexander Duyck <alexander.duyck@...il.com>,
        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>,
        Alexander Lobakin <alexandr.lobakin@...el.com>,
        Gal Pressman <gal@...dia.com>, Dave Taht <dave.taht@...il.com>,
        Bjørn Mork <bjorn@...k.no>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        netdev@...r.kernel.org
Subject: Re: [PATCH net-next v4 0/3] add tx packets aggregation to ethtool and rmnet

Hello Jakub and Alexander,

Il giorno ven 13 gen 2023 alle ore 20:48 Jakub Kicinski
<kuba@...nel.org> ha scritto:
>
> On Fri, 13 Jan 2023 08:16:48 -0800 Alexander Duyck wrote:
> > > ETHTOOL_A_COALESCE_TX_AGGR_MAX_FRAMES works also as a way to determine
> > > that tx aggregation has been enabled by the userspace tool managing
> > > the qmi requests, otherwise no aggregation should be performed.
> >
> > Is there a specific reason why you wouldn't want to take advantage of
> > aggregation that is already provided by the stack in the form of
> > things such as GSO and the qdisc layer? I know most of the high speed
> > NICs are always making use of xmit_more since things like GSO can take
> > advantage of it to increase the throughput. Enabling BQL is a way of
> > taking that one step further and enabling the non-GSO cases.
>
> The patches had been applied last night by DaveM but FWIW I think
> Alex's idea is quite interesting. Even without BQL I believe you'd
> get xmit_more set within a single GSO super-frame. TCP sends data
> in chunks of 64kB, and you're only aggregating 32kB. If we could
> get the same effect without any added latency and user configuration
> that'd be great.

Thanks for the hints, I'll explore xmit_more usage and try to gather
some numbers to compare the two solutions.

Regards,
Daniele