RE: [RFC net-next 2/2] net: fec: add ndo_select_queue to fix TX bandwidth fluctuations

Hi Andrew,

-----Original Message-----
From: Andrew Lunn <andrew@lunn.ch>
Sent: 2021年5月23日 22:46
To: Joakim Zhang <redacted>
Cc: davem@davemloft.net; kuba@kernel.org; frieder.schrempf@kontron.de;
netdev@vger.kernel.org; linux-kernel@vger.kernel.org; dl-linux-imx
[off-list ref]
Subject: Re: [RFC net-next 2/2] net: fec: add ndo_select_queue to fix TX
bandwidth fluctuations

On Sun, May 23, 2021 at 06:20:19PM +0800, Joakim Zhang wrote:

quoted

From: Fugang Duan <redacted>

As we know that AVB is enabled by default, and the ENET IP design is
queue 0 for best effort, queue 1&2 for AVB Class A&B. Bandwidth of
queue 1&2 set in driver is 50%, TX bandwidth fluctuated when selecting
tx queues randomly with FEC_QUIRK_HAS_AVB quirk available.

How is the driver currently scheduling between these queues? Given the
802.1q priorities, i think we want queue 2 with the highest priority for
scheduling. Then queue 0 and lastly queue 1.

I think currently there is no schedule between these queues in the driver.

Could you please point me where I can find mapping between priorities and queues? You prefer to below mapping?
static const u16 fec_enet_vlan_pri_to_queue[8] = {1, 1, 0, 0, 0, 2, 2, 2};

Best Regards,
Joakim Zhang

    Andrew