[ovs-discuss] Packet drops during non-exhaustive flood with OVS and 1.8.0

Traynor, Kevin kevin.traynor at intel.com
Fri Feb 13 10:58:23 UTC 2015


> -----Original Message-----
> From: Andrey Korolyov [mailto:andrey at xdel.ru]
> Sent: Thursday, February 12, 2015 3:16 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
> 
> On Thu, Feb 12, 2015 at 6:05 PM, Traynor, Kevin <kevin.traynor at intel.com> wrote:
> >> -----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
> >
> 
> Do you mind to compare this case with forward to the dummy port
> (ifconfig dummy0; ovs-vsctl add-port br0 dummy0; ip link set dev
> dummy0 up; flush rule table; create a single forward rule; start an
> attack)? As I mentioned there are no signs of syscall congestion for a
> drop or dpdk-dpdk forward case.

Assuming I've understood your setup, I get a very low rate (~1.1 mpps) 
without packet loss as I'm sending the packets from a dpdk port to a 
socket for the dummy port 


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