Wrong rx queue assignment running DPDK on Azure

[Yang Luan]

We use netvsc PMD (drivers/net/netvsc/).
We don't explicitly configure the RETA table. We configure the device with
40 rx queues (rte_eth_dev_configure) and use rte_eth_dev_rss_reta_query()
to query the RETA table (result posted earlier).

On Fri, Nov 4, 2022 at 9:52 AM Stephen Hemminger <stephen at networkplumber.org>
wrote:

> On Tue, 1 Nov 2022 17:25:24 -0700
> Yang Luan <luan.penny at gmail.com> wrote:
>
> > Hello,
> >
> >
> > Our application uses the net_netvsc driver in DPDK 21.08 on Azure. We
> found
> > an issue where RSS doesn’t deliver packets to the correct rx queue. The
> > instance type we use is Standard_L80s_v3 with MT27800 Family [ConnectX-5
> > Virtual Function] NICs. The NIC is configured with 40 rx queues and the
> > RETA table is configured (confirmed by rte_eth_dev_rss_reta_query()) as
> > below.
> >
> >
> >
> >   0:       0    1    2    3    4    5    6    7
> >
> >   8:       8    9   10   11   12   13   14   15
> >
> >  16:      16   17   18   19   20   21   22   23
> >
> > 24:      24   25   26   27   28   29   30   31
> >
> > 32:      32   33   34   35   36   37   38   39
> >
> > 40:       0    1    2    3    4    5    6    7
> >
> > 48:       8    9   10   11   12   13   14   15
> >
> > 56:      16   17   18   19   20   21   22   23
> >
> > 64:      24   25   26   27   28   29   30   31
> >
> > 72:      32   33   34   35   36   37   38   39
> >
> > 80:       0    1    2    3    4    5    6    7
> >
> > 88:       8    9   10   11   12   13   14   15
> >
> > 96:      16   17   18   19   20   21   22   23
> >
> > 104:      24   25   26   27   28   29   30   31
> >
> > 112:      32   33   34   35   36   37   38   39
> >
> > 120:       0    1    2    3    4    5    6    7
> >
> >
> >
> > One example is a packet received with rss key 0xEDE25D84 was incorrectly
> > delivered to rx queue 12. We expect it to be queue 4 as 0xEDE25D84 &
> 0x7F =
> > 4 assuming seven of the least significant bits (LSBs) are used for
> indexing
> > into the RETA table.  Is it a bug or we made a wrong assumption on how
> the
> > RETA table is accessed with that device?
> >
> >
> > Thank you.
> >
> > Yang
>
> Are you using failsafe PMD or the native netvsc PMD?
> Are you programming reta table via DPDK or through other API's?
>
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