[dpdk-users] DPDK Distributor app issues
gesha2 at abv.bg
Tue Jun 11 08:40:13 CEST 2019
Harry, thank you for the answer.
I will look into this event dev lib, but I hoped my time with the distributor lib will not be wasted. Actually it pretty much fits into my use case.
About the packet loss I suspect that they are always the first one or two packets, I'm still debugging and trying to figure out what really happens.
About the delay - unfortunately the cycles in the worker are not the cause for them. When I comment these lines there is no effect on the delay. Also these is some buffering happening in the tx_core but the reason is not there also. I suspect some buffering happens internally in the distributor itself. I understand that the throughput is traded for bigger latency, but hoped there will be a way to tune this.
>-------- Оригинално писмо --------
>От: "Van Haaren, Harry" harry.van.haaren at intel.com
>Относно: RE: [dpdk-users] DPDK Distributor app issues
>До: George Yaneff , "users at dpdk.org"
>Изпратено на: 10.06.2019 19:13
> -----Original Message-----
> From: users [mailto:users-bounces at dpdk.org] On Behalf Of George Yaneff
> Sent: Monday, June 10, 2019 3:40 PM
> To: users at dpdk.org
> Subject: [dpdk-users] DPDK Distributor app issues
> I'm playing with the distributor example application from dpdk 19.05.0
Ah cool - Not sure what your goal is, but if you're looking for the
more future-proof load-balancing / distribution APIs in DPDK the I
recommend to look at the Eventdev library, as this has been added to
DPDK for more "pipelined" applications and load-balancing within those
If you know your use case matches distributor library, and are aware of
the existence of Eventdev libs, please ignore the above :)
> have three machines connected sequentially with an UTP Ethernet cable. The
> middle is Ubuntu 18.04.2 LTS with a eigth core Intel I7 processor and 24
> GB ram. The eth device used is Intel I350 with four ports.
> The strange behavior I'm observing is when I ping the second node from the
> first node (traffic passing through the distributor) there are always one
> or two packets lost.
> When I use
> l2fwd or
> basicfwd applications there is no packet loss. Anyone knows if this is
> normal or if it is not - what I'm doing wrong?
This seems strange - although I'm not very familiar with Distributor sample app.
Perhaps add some statistics counters around the "rte_pktmbuf_free()" calls in
the sample app, to identify if the sample-app is dropping packets in SW, or if
the root cause is really platform configuration?
> Another thing I noticed is that the ping replies come to the first node
> with around one second of delay. (1024ms on most packets) Again there is no
> latency with the basicfwd (packets arriving in 0.101 ms there). Is there
> any way to minimize this delay in distributor application also?
The sample application adds artificial "work" per packet to simulate a real
world distributing workload:
Per packet, 100 cycles of work is performed, so eg:
(burst-size # of packets * 100 cycles) @ CPU freq + RX, TX and Distributor
work will be the total delay along the wire.
Hope that helps, -Harry
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