[Observium] graphs shows peaks huawei S6700

Hello

I'm using Observium latest version. Most of the grapsh for interfaces are pretty good. But for 2 Huaweis switches S6730, the collected data appears kind of 'saw':

Same device, polled with a Cacti server, shows this way:

A few 'spikes' but far more smooth graph.

The polling time is between 10 to 13 seconds, CPU ok, memory too.

Can someone have an idea what to do to avoid the spikes?

Regards