linux-kernel - Re: [PATCH net-next v2] net: lan966x: Improve the CPU TX bitrate.

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Date:   Thu, 10 Mar 2022 15:36:23 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Horatiu Vultur <horatiu.vultur@...rochip.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        UNGLinuxDriver@...rochip.com, davem@...emloft.net, kuba@...nel.org,
        david.laight@...lab.com
Subject: Re: [PATCH net-next v2] net: lan966x: Improve the CPU TX bitrate.

On Thu, Mar 10, 2022 at 09:40:05AM +0100, Horatiu Vultur wrote:
> When doing manual injection of the frame, it is required to check if the
> TX FIFO is ready to accept the next word of the frame. For this we are
> using 'readx_poll_timeout_atomic', the only problem is that before it
> actually checks the status, is determining the time when to finish polling
> the status. Which seems to be an expensive operation.
> Therefore check the status of the TX FIFO before calling
> 'readx_poll_timeout_atomic'.
> Doing this will improve the TX bitrate by ~70%. Because 99% the FIFO is
> ready by that time. The measurements were done using iperf3.
> 
> Before:
> [ ID] Interval           Transfer     Bitrate         Retr
> [  5]   0.00-10.03  sec  55.2 MBytes  46.2 Mbits/sec    0 sender
> [  5]   0.00-10.04  sec  53.8 MBytes  45.0 Mbits/sec      receiver
> 
> After:
> [ ID] Interval           Transfer     Bitrate         Retr
> [  5]   0.00-10.10  sec  95.0 MBytes  78.9 Mbits/sec    0 sender
> [  5]   0.00-10.11  sec  95.0 MBytes  78.8 Mbits/sec      receiver
> 
> Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew