Re: [dpdk-dev] [PATCH v1] ixgbe_pmd: forbid tx_rs_thresh above 1 for all NICs but 82598

[Vladislav Zolotarov <vladz@cloudius-systems.com>]

On Sep 9, 2015 4:19 PM, "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
wrote:
>
> Hi Thomas,
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Thomas Monjalon
> > Sent: Wednesday, September 09, 2015 1:19 PM
> > To: Zhang, Helin
> > Cc: dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH v1] ixgbe_pmd: forbid tx_rs_thresh above
1 for all NICs but 82598
> >
> > 2015-08-25 20:13, Zhang, Helin:
> > > Yes, I got the perfect answers. Thank you very much!
> > > I just wanted to make sure the test case was OK with the limit of
maximum number of descriptors, as I heard there is a hang issue on
> > other NICs of using more descriptors than hardware allowed.
> > > OK. I am still waiting for the answers/confirmation from x540
hardware designers. We need all agree on your patches to avoid risks.
> >
> > Helin, any news?
> > Can we apply v4 of this patch?
>
> Unfortunately we are seeing a huge performance drop with that patch:
> On my box bi-directional traffic (64B packet) over one port can't reach
even 11 Mpps.

Konstantin, could u clarify - u saw "only" 11 Mpps with v3 of this patch
which doesn't change the rs_thresh and only sets RS on every packet? What
is the performance in the same test without this patch?

> We are still doing some experiments and consultations with ND guys how we
can overcome
> this problem and keep performance intact.
>
> Konstantin