Re: [PATCH net-next v2 0/2] Add HW checksum offload support for RZ/G2L GbEthernet IP

From: Sergey Shtylyov <s.shtylyov@omp.ru>
To: Biju Das <biju.das.jz@bp.renesas.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
	<peterz@infradead.org>,
	Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Nikita Yushchenko <nikita.yoush@cogentembedded.com>,
	<netdev@vger.kernel.org>, <linux-renesas-soc@vger.kernel.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>,
	Biju Das <biju.das.au@gmail.com>
Subject: Re: [PATCH net-next v2 0/2] Add HW checksum offload support for RZ/G2L GbEthernet IP
Date: Thu, 25 Jan 2024 22:10:55 +0300	[thread overview]
Message-ID: <5245e582-5eea-ccdf-2ba3-fda58e261172@omp.ru> (raw)
In-Reply-To: <20240124102115.132154-1-biju.das.jz@bp.renesas.com>

Hello!

On 1/24/24 1:21 PM, Biju Das wrote:

> This patch series aims to add HW checksum offload supported by TOE module
> found on the RZ/G2L Gb ethernet IP.

   Your previous try was back in 2021, still the cover letter has the same
issues (hm, I didn't point out those back then).

> The TOE has hw support for calculating IP header and TCP/UDP/ICMP checksum
> for both IPV4 and IPV6.
> 
> For Rx, the result of checksum calculation is attached to last 4byte
> of ethernet frames.

   "For Rx, the 4-byte result of checksum calculation is attached to the
Ethernet frames", you wanted to say?

> First 2bytes is result of IPV4 header checksum
> and next 2 bytes is TCP/UDP/ICMP.

   TCP/UDP/ICMP checksum, you mean?

> If frame does not have error "0000" attached to checksum calculation

   "If a frame does not have error, 0x0000 is attached as a checksum
calculation result", you wanted to say?

> result. For unsupported frames "ffff" is attached to checksum calculation

   s/to/as/, again?

> result. Cases like IPV6, IPV4 header is always set to "FFFF".

   In case of an IPv6 packet, IPv4 checksum is always set to 0xFFFF",
you wanted to say?

> For Tx, the result of checksum calculation is set to the checksum field of
> each IPv4 Header/TCP/UDP/ICMP of ethernet frames. For the unsupported
> frames, those fields are not changed. If a transmission frame is an UDP
> frame of IPv4 and its checksum value in the UDP header field is H’0000,

   I think you can call it just UDPv4...

> TOE does not calculate checksum for UDP part of this frame as it is
> optional function as per standards.
> 
> Add Tx/Rx checksum offload supported by TOE for IPV4 and TCP/UDP protocols.
> 
> Results of iperf3 in Mbps
> 
> RZ/V2L:
> TCP(Tx/Rx) results with checksum offload Enabled:	{921,932}
> TCP(Tx/Rx) results with checksum offload Disabled:	{867,612}
> 
> UDP(Tx/Rx) results with checksum offload Enabled:	{950,946}
> UDP(Tx/Rx) results with checksum offload Disabled:	{952,920}
> 
> RZ/G2L:
> TCP(Tx/Rx) results with checksum offload Enabled:	{920,936}
> TCP(Tx/Rx) results with checksum offload Disabled:	{871,626}
> 
> UDP(Tx/Rx) results with checksum offload Enabled:	{953,950}
> UDP(Tx/Rx) results with checksum offload Disabled:	{954,920}
> 
> RZ/G2LC:
> TCP(Tx/Rx) results with checksum offload Enabled:	{927,936}
> TCP(Tx/Rx) results with checksum offload Disabled:	{889,626}
> 
> UDP(Tx/Rx) results with checksum offload Enabled:	{950,946}
> UDP(Tx/Rx) results with checksum offload Disabled:	{949,944}

   Too many figures, I think... :-)
   How RZ/G2L SoC is different from RZ/G2LC?

> v1->v2:
>  * Updated covering letter and results
>  * Fixed the sparse warnings for patch#1 by replacing __sum16->__wsum.
> 
> Note:
>  This patches are tested with [1] without the CPU performance is not good

   Without CPU? I guess the performance would be 0. Seriously, this is
hardly parseable... :-)

>  [1] https://lore.kernel.org/all/20240117190545.596057-1-vincent.guittot@linaro.org/
> 
> Biju Das (2):
>   ravb: Add Rx checksum offload support
>   ravb: Add Tx checksum offload support

   These summaries sound like you're adding checksum offload support for
all supported SoCs while you only do that for those having GbEther...

[...]

MBR, Sergey