[dpdk-dev] Packet drops during non-exhaustive flood with OVS and 1.8.0

[Traynor, Kevin]

> -----Original Message-----
> From: Andrey Korolyov [mailto:andrey at xdel.ru]
> Sent: Tuesday, February 3, 2015 5:21 PM
> To: Traynor, Kevin
> Cc: dev at dpdk.org; discuss at openvswitch.org
> Subject: Re: Packet drops during non-exhaustive flood with OVS and 1.8.0
> 
> > These patches are to enable DPDK 1.8 only. What 'bulk processing' are you referring to?
> > By default there is a batch size of 192 in netdev-dpdk for rx from the NIC - the linked
> > patch doesn't change this, just the DPDK version.
> 
> Sorry, I referred the wrong part there: bulk transmission, which is
> clearly not involved in my case. The idea was that the conditionally
> enabling prefetch for rx queues (BULK_ALLOC) may help somehow, but
> it`s probably will mask issue instead of solving it directly. By my
> understanding, strict drop rule should have a zero impact on a main
> ovs thread (and this is true) and work just fine with a line rate
> (this is not).

I've set a similar drop rule and I'm seeing the first packet drops occurring 
at 13.9 mpps for 64 byte pkts. I'm not sure if there is a config that can be 
changed or if it just the cost of the emc/lookups

> 
> >
> > Main things to consider are to isocpu's, pin the pmd thread and keep everything
> > on 1 NUMA socket. At 11 mpps without packet loss on that processor I suspect you are
> > doing those things already.
> 
> Yes, with all tuning improvements I was able to do this, but bare
> Linux stack on same machine is able to handle 12Mpps and there are
> absolutely no hints of what exactly is being congested.