[dpdk-users] Small constant frame loss only for more than 5 seconds of traffic at 10Gbps

[DESBRUS Maxime <maxime.desbrus@thalesgroup.com>]

Hello

I am trying to capture 60 B Ethernet frames at link speed on two 10GbE ports with DPDK 17.08 on Linux 4.4 and an Intel XL710 card.

I use a slightly modified version of the l2fwd example program, that only counts incoming frames and immediately releases the mbufs.

I see a strange behavior because I can capture without any loss for 5s of traffic, but for more than that I always lose a few frames (about 15 000). For 10, 30 or 60 seconds of traffic the number of lost frames does not change much (it is a constant, and not a percentage of the incoming traffic).

I did apply all the recommendations to eliminate perturbations on the working cores:
* isolate cores with isolcpus, nohz_full, rcu_nocbs boot parameters
* disable hyper threading
* disable NMI watchdog
* disable pstate frequency scaling
* disable pause frames on both sides

I also tried to tweak a few things:
* increase/decrease mbuf pool size
* use a dedicated rte_mempool object per port
* increase/decrease packet burst length
* increase/decrease rx descriptor count

Although some of these did decrease loss a bit, I still get a few thousands lost frames for more than 5 seconds of incoming traffic.

I don't understand why performance seem to change only after a few seconds of traffic.

Any ideas?

Thanks

--
Maxime DESBRUS