stmmac: Performance regression after commit aff3d9eff843 "net: stmmac: enable multiple buffers"

[Giuseppe CAVALLARO]

On 3/23/2017 11:48 AM, Giuseppe CAVALLARO wrote:
> Hello
>
> On 3/23/2017 11:20 AM, Corentin Labbe wrote:
>>> I have a 4.21 QoS Core with 4 RX + 4 TX and detected no regression.
>>> >Could you please share the iperf cmds you are using in order for me 
>>> to reproduce
>>> >in my side?
>
> Joao, you have a really powerful HW integration with multiple channels 
> for both RX and TX.
> Often this is not the same for other setup where, usually just a DMA0 
> is present or, sometime, there
> is just one RX extra channel.
>
> My question is, what happens on this kind of configurations? Are we 
> still guarantying the best performances?
>
> Also we have to guarantee, that the TSO and SG are always working. 
> Another point is the buffer sizes that
> can be different among platforms.
>
> The problem  below reported by Corentin push me to think that there is 
> a bug, so we should
> understand when this has been introduced and if likely fixed by some 
> configuration we are
> not take care right now.
>
> ndesc_get_rx_status: Oversized frame spanned multiple buffers"

I wonder if this could be easily triggered by getting a big file via 
FTP. So not properly related on performance benchs

peppe

>
>
> Best Regards
> Peppe
>