RE: [PATCH] net/i40e: increase descriptor queue length to 8160

["Morten Brørup" <mb@smartsharesystems.com>]

> From: Igor Gutorov [mailto:igootorov@gmail.com]
> Sent: Wednesday, 5 June 2024 12.47
> 
> On Mon, Jun 3, 2024 at 1:41 PM Igor Gutorov <igootorov@gmail.com> wrote:
> >
> > On Mon, May 27, 2024 at 7:20 PM Igor Gutorov <igootorov@gmail.com> wrote:
> > >
> > > According to the Intel X710/XXV710/XL710 Datasheet, the maximum receive
> > > queue descriptor length is 0x1FE0 (8160 in base 10). This is specified
> > > as QLEN in table 8-12, page 1083.
> > >
> > > I've tested this change with an XXV710 NIC and it has positive effect on
> > > performance under high load scenarios. Where previously I'd get
> > > ~2000 packets/sec miss rate, now I get only ~40 packets/sec miss rate.
> > >
> > > Signed-off-by: Igor Gutorov <igootorov@gmail.com>
> > > ---
> > >  drivers/net/i40e/i40e_rxtx.h | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/net/i40e/i40e_rxtx.h b/drivers/net/i40e/i40e_rxtx.h
> > > index 2f2f890855..33fc9770d9 100644
> > > --- a/drivers/net/i40e/i40e_rxtx.h
> > > +++ b/drivers/net/i40e/i40e_rxtx.h
> > > @@ -25,7 +25,7 @@
> > >  #define I40E_RX_MAX_DATA_BUF_SIZE      (16 * 1024 - 128)
> > >
> > >  #define        I40E_MIN_RING_DESC      64
> > > -#define        I40E_MAX_RING_DESC      4096
> > > +#define        I40E_MAX_RING_DESC      8160
> > >
> > >  #define I40E_FDIR_NUM_TX_DESC   (I40E_FDIR_PRG_PKT_CNT << 1)
> > >  #define I40E_FDIR_NUM_RX_DESC   (I40E_FDIR_PRG_PKT_CNT << 1)
> > > --
> > > 2.45.1
> > >
> >
> > CC'ing to a different email (got an address rejected error, the
> > MAINTAINERS file might need an update).
> >
> > Also, I've noticed that an X722 NIC is also supported by the i40e
> > driver, but it seems the datasheet isn't on Intel's website for that
> > NIC. Does anybody know if X722 has 4096 or 8160 usable descriptors?

It does.
Refer to table 38-419, page 3086 in the Intel C620 Chipset datasheet:
https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/c620-series-chipset-datasheet.pdf

> > If
> > someone could test this patch against X722, that would be great.

I don't have one, so I cannot test it. But:
Acked-by: Morten Brørup <mb@smartsharesystems.com>

> 
> Apologies for pinging again. Who should I send my patch to? The
> MAINTAINERS file shows Yuying Zhang as the maintainer of the net/i40e
> driver and contains 2 emails, but both Yuying.Zhang@intel.com and
> yuying.zhang@intel.com emails are non-existent (550 Address rejected).

The i40e DPDK driver is currently without maintainers.
Sending the patch to the dev@dpdk.org mailing list suffices.