Date: Sat, 10 Feb 2024 22:36:16 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Paul Barker <paul.barker.ct@...renesas.com>, "David S . Miller"
	<davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
	<kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
CC: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>, Wolfram Sang
	<wsa+renesas@...g-engineering.com>, <netdev@...r.kernel.org>,
	<linux-renesas-soc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH net-next v2 0/7] Improve GbEth performance on Renesas
 RZ/G2L and related SoCs

On 2/6/24 12:19 PM, Paul Barker wrote:

> This series aims to improve peformance of the GbEth IP in the Renesas

   You didn't fix the typo in "peformance"... :-/

> RZ/G2L SoC family and the RZ/G3S SoC, which use the ravb driver. Along
> the way, we do some refactoring and ensure that napi_complete_done() is
> used in accordance with the NAPI documentation for both GbEth and R-Car
> code paths.
> 
> Performance improvment mainly comes from enabling SW IRQ Coalescing for

   And in "improvment" too... :-/

> all SoCs using the GbEth IP, and NAPI Threaded mode for single core SoCs
> using the GbEth IP. These can be enabled/disabled at runtime via sysfs,
> but our goal is to set sensible defaults which get good performance on
> the affected SoCs.
> 
> The performance impact of this series on iperf3 testing is as follows:
>   * RZ/G2L Ethernet throughput is unchanged, but CPU usage drops:
>       * Bidirectional and TCP RX: 6.5% less CPU usage
>       * UDP RX: 10% less CPU usage
> 
>   * RZ/G2UL and RZ/G3S Ethernet throughput is increased for all test
>     cases except UDP TX, which suffers a slight loss:
>       * TCP TX: 32% more throughput
>       * TCP RX: 11% more throughput
>       * UDP TX: 10% less throughput
>       * UDP RX: 10183% more throughput - the previous throughput of

   So this is a real figure? I thought you forgot to erase 10... :-)

>         1.06Mbps is what prompted this work.
> 
>   * RZ/G2N CPU usage and Ethernet throughput is unchanged (tested as a
>     representative of the SoCs which use the R-Car based RAVB IP).
> 
> This series depends on:
>   * "net: ravb: Let IP-specific receive function to interrogate descriptors" v6
>     https://lore.kernel.org/all/20240202084136.3426492-2-claudiu.beznea.uj@bp.renesas.com/

   This one has been merged now, so you can drop RFC...

> To get the results shown above, you'll also need:
>   * "topology: Set capacity_freq_ref in all cases"
>     https://lore.kernel.org/all/20240117190545.596057-1-vincent.guittot@linaro.org/
> 
>   * "ravb: Add Rx checksum offload support" v4
>     https://lore.kernel.org/all/20240203142559.130466-2-biju.das.jz@bp.renesas.com/
> 
>   * "ravb: Add Tx checksum offload support" v4
>     https://lore.kernel.org/all/20240203142559.130466-3-biju.das.jz@bp.renesas.com/

   These two have been merged too...

> Work in this area will continue, in particular we expect to improve
> TCP/UDP RX performance further with future changes to RX buffer
> handling.
> 
> Changes v1->v2:
>   * Marked as RFC as the series depends on unmerged patches.
>   * Refactored R-Car code paths as well as GbEth code paths.
>   * Updated references to the patches this series depends on.
> 
> Paul Barker (7):
>   net: ravb: Simplify poll & receive functions

   The below 3 commits fix issues in the GbEth code, so should
be redone against net.git and posted separately from this series...

>   net: ravb: Count packets instead of descriptors in RX path
>   net: ravb: Always process TX descriptor ring
>   net: ravb: Always update error counters

[...]

MBR, Sergey

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