netdev - Re: [PATCH net-next v2 3/4] tsnep: Throttle interrupts

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Message-ID: <Y4fe7i+UypsTbWgQ@lunn.ch>
Date:   Wed, 30 Nov 2022 23:53:34 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Gerhard Engleder <gerhard@...leder-embedded.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        edumazet@...gle.com, pabeni@...hat.com
Subject: Re: [PATCH net-next v2 3/4] tsnep: Throttle interrupts

On Wed, Nov 30, 2022 at 08:37:07PM +0100, Gerhard Engleder wrote:
> Without interrupt throttling, iperf server mode generates a CPU load of
> 100% (A53 1.2GHz). Also the throughput suffers with less than 900Mbit/s
> on a 1Gbit/s link. The reason is a high interrupt load with interrupts
> every ~20us.
> 
> Reduce interrupt load by throttling of interrupts. Interrupt delay
> default is 64us. For iperf server mode the CPU load is significantly
> reduced to ~20% and the throughput reaches the maximum of 941MBit/s.
> Interrupts are generated every ~140us.
> 
> RX and TX coalesce can be configured with ethtool. RX coalesce has
> priority over TX coalesce if the same interrupt is used.
> 
> Signed-off-by: Gerhard Engleder <gerhard@...leder-embedded.com>

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

    Andrew