[RFC v2 3/7] ethdev: introduce Rx queue based limit watermark

[Spike Du]

Hi,

> -----Original Message-----
> From: Stephen Hemminger <stephen at networkplumber.org>
> Sent: Sunday, May 22, 2022 11:25 PM
> To: Spike Du <spiked at nvidia.com>
> Cc: Matan Azrad <matan at nvidia.com>; Slava Ovsiienko
> <viacheslavo at nvidia.com>; Ori Kam <orika at nvidia.com>; NBU-Contact-
> Thomas Monjalon (EXTERNAL) <thomas at monjalon.net>; dev at dpdk.org;
> Raslan Darawsheh <rasland at nvidia.com>
> Subject: Re: [RFC v2 3/7] ethdev: introduce Rx queue based limit watermark
> 
> External email: Use caution opening links or attachments
> 
> 
> On Sun, 22 May 2022 08:58:56 +0300
> Spike Du <spiked at nvidia.com> wrote:
> 
> > LWM(limit watermark) describes the fullness of a Rx queue. If the Rx
> > queue fullness is above LWM, the device will trigger the event
> > RTE_ETH_EVENT_RX_LWM.
> > LWM is defined as a percentage of Rx queue size with valid value of
> > [0,99].
> > Setting LWM to 0 means disable it, which is the default.
> > When translate the percentage to queue descriptor number, the numbe
> > should be bigger than 0 and less than queue size.
> > Add LWM's configuration and query driver callbacks in eth_dev_ops.
> >
> > Signed-off-by: Spike Du <spiked at nvidia.com>
> 
> One other objection, please don't invent yet another event channel for this.
> It should be part of existing Rx interrupt logic.

I think this is misunderstanding, the "event channel" is a specific concept in MLX5 PMD.
For the DPDK common code like testpmd and event register/callback, I'm using standard dpdk
interfaces.