RE: [Patch v2] net/netvsc: report correct stats values

[Long Li <longli@microsoft.com>]

> Subject: Re: [Patch v2] net/netvsc: report correct stats values
> 
> On 5/3/2022 8:14 PM, Long Li wrote:
> >> Subject: Re: [Patch v2] net/netvsc: report correct stats values
> >>
> >> On 5/3/2022 7:18 PM, Long Li wrote:
> >>>> Subject: Re: [Patch v2] net/netvsc: report correct stats values
> >>>>
> >>>> On Tue, 26 Apr 2022 22:56:14 +0100
> >>>> Ferruh Yigit <ferruh.yigit@xilinx.com> wrote:
> >>>>
> >>>>>>     		if (i < RTE_ETHDEV_QUEUE_STAT_CNTRS) {
> >>>>>> -			stats->q_opackets[i] = txq->stats.packets;
> >>>>>> -			stats->q_obytes[i] = txq->stats.bytes;
> >>>>>> +			stats->q_opackets[i] += txq->stats.packets;
> >>>>>> +			stats->q_obytes[i] += txq->stats.bytes;
> >>>>>
> >>>>> This is per queue stats, 'stats->q_opackets[i]', in next iteration
> >>>>> of the loop, 'i' will be increased and 'txq' will be updated, so
> >>>>> as far as I can see the above change has no affect.
> >>>>
> >>>> Agree, that is why it was just assignment originally.
> >>>
> >>> The condition here is a little different. NETVSC is a master device
> >>> with
> >> another PMD running as a slave. When reporting stats values, it needs
> >> to add the values from the slave PMD. The original code just
> >> overwrites the values from its slave PMD.
> >>
> >> Where the initial values are coming from, 'hn_vf_stats_get()'?
> >>
> >> If 'hn_vf_stats_get()' fills the stats, what are the values kept in 'txq-
> >stats.*'
> >> in above updated loop?
> >
> > Yes, hn_vf_stats_get() fills in the stats from the slave PMD. txq->stats
> values are from the master PMD. Those values are different and accounted
> separated from the values from the slave PMD.
> 
> I see, since this is a little different than what most of the PMDs do, can you
> please put a little more info to the commit log? Or perhaps can add some
> comments to the code.

Ok, will do.

> 
> And still 'stats->rx_nombuf' change is not required right? If so can you
> remove it in the next version?

It is still needed. NETVSC unconditionally calls the slave PMD to receive packets, even if it can't allocate a mbuf to receive a synthetic packet itself. The accounting of rx_nombuf is valid because the synthetic packets (to NETVSC) and VF packets (to slave PMD) are routed separately from Hyper-V.