Re: [PATCH net 0/2] net: stmmac: Track and report the TX DMA threshold per queue

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hi Ovidiu,

On 10/13/26 13:45, Ovidiu Panait wrote:
> On the Renesas RZ/V2H platform, which has two dwmac4 controllers, we
> observed sporadic iperf3 TCP TX failures on one of the controllers, with
> throughput dropping from >900Mbit/s to ~1Mbit/s due to TX underflows and
> the resulting retransmissions.
> 
> Commit 3a6c12a0c6c3 ("net: stmmac: bump tc when get underflow error from
> DMA descriptor") made dwmac4 raise the DMA threshold of the queues that
> report TX underflows, by increasing a global module parameter 'tc'.
> However, this logic does not work correctly across multiple queues and
> controllers, and can leave the TX DMA threshold stuck at 64 bytes.
> 
> This series fixes that logic to track and report the TX DMA threshold per
> queue for each controller.

That's a nice cleanup, thanks for addressing it :)

Patch 2 belongs to net-next though, it's not a fix and it brings some user-visible
changes in the stats.

Thanks,

Maxime