Re: [PATCH net-next 2/3] net: qualcomm: rmnet: add tx packets aggregation

From: Daniele Palmas <dnlplm@gmail.com>
To: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: "David Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Eric Dumazet" <edumazet@google.com>,
	"Subash Abhinov Kasiviswanathan" <quic_subashab@quicinc.com>,
	"Sean Tranchetti" <quic_stranche@quicinc.com>,
	"Jonathan Corbet" <corbet@lwn.net>, "Bjørn Mork" <bjorn@mork.no>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	netdev@vger.kernel.org
Subject: Re: [PATCH net-next 2/3] net: qualcomm: rmnet: add tx packets aggregation
Date: Wed, 16 Nov 2022 16:19:48 +0100	[thread overview]
Message-ID: <CAGRyCJHmNgzVVnGunUh7wwKxYA7GzSvfgqPDAxL+-NcO2P+1wg@mail.gmail.com> (raw)
In-Reply-To: <20221110173222.3536589-1-alexandr.lobakin@intel.com>

Hello Alexander,

Il giorno gio 10 nov 2022 alle ore 18:35 Alexander Lobakin
<alexandr.lobakin@intel.com> ha scritto:
>
> Do I get the whole logics correctly, you allocate a new big skb and
> just copy several frames into it, then send as one chunk once its
> size reaches the threshold? Plus linearize every skb to be able to
> do that... That's too much of overhead I'd say, just handle S/G and
> fraglists and make long trains of frags from them without copying
> anything?

sorry for my question, for sure I'm lacking knowledge about this, but
I'm trying to understand how I can move forward.

Suppose I'm able to build the aggregated block as a train of
fragments, then I have to send it to the underlying netdevice that, in
my scenario, is created by the qmi_wwan driver: I could be wrong, but
my understanding is that it does not support fragments.

And, as far as I know, there's only another driver in mainline used
with rmnet (mhi_net) and that one also does not seem to support them
either.

Does this mean that once I have the aggregated block through fragments
it should be converted to a single linear skb before sending?

Thanks,
Daniele