Re: [dpdk-users] Mellanox ConnectX-4, DPDK and extreme latency issues

["Nélio Laranjeiro" <nelio.laranjeiro@6wind.com>]

On Mon, Sep 04, 2017 at 05:52:52PM +0200, Adrien Mazarguil wrote:
> Arjun,
> 
> On Thu, Jun 29, 2017 at 05:26:02AM +0000, Shahaf Shuler wrote:
> > Hi Arjun,
> > 
> > Thursday, June 22, 2017 9:40 PM, Arjun Roy,
> > > 
> > > Greetings all.
> > > 
> > > I have a weird issue regarding excessive latency using Mellanox ConnectX-4
> > > 100Gbe cards, DPDK and packet forwarding. Specifically: running the l3fwd
> > > and basicfwd DPDK example programs yields ping latencies of several (5-8)
> > > milliseconds. I tried the same test using an Intel X-540 AT2 card on the same
> > > systems and the latency was on the order of 4-5 microseconds.
> > 
> > Thanks for reporting.
> > This is the first time we hit such scenario, we will check it internally and will get back to you with answers. 
> 
> Back to this topic, could it be the same issue as reported by Sagi,
> "mlx5 high latency observed on send operations" [1]?
> 
> The related patches have been submitted and are on track for DPDK 17.11.
> While they are not yet on the master tree, you can find them on
> dpdk-next-net.
> 
> [1] http://dpdk.org/ml/archives/dev/2017-August/073081.html

Note this patches are not enough, there is also an issue on Verbs side, the
fixes there should be part of the next MLNX_OFED 4.2, otherwise it is already
fixed in rdma-core but for that it will need the PMD support for that [1].

Regards,

[1] http://dpdk.org/ml/archives/dev/2017-September/074278.html
-- 
Nélio Laranjeiro
6WIND