[dpdk-dev] Performance regression in DPDK 1.8/2.0
De Lara Guarch, Pablo
pablo.de.lara.guarch at intel.com
Mon Apr 27 19:38:38 CEST 2015
Hi,
> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Pavel Odintsov
> Sent: Monday, April 27, 2015 9:07 AM
> To: Paul Emmerich
> Cc: dev at dpdk.org
> Subject: Re: [dpdk-dev] Performance regression in DPDK 1.8/2.0
>
> Hello!
>
> I executed deep test of Paul's toolkit and could approve performance
> degradation in 2.0.0.
>
> On Sun, Apr 26, 2015 at 9:50 PM, Paul Emmerich <emmericp at net.in.tum.de>
> wrote:
> > Hi,
> >
> > I'm working on a DPDK-based packet generator [1] and I recently tried to
> > upgrade from DPDK 1.7.1 to 2.0.0.
> > However, I noticed that DPDK 1.7.1 is about 25% faster than 2.0.0 for my
> use
> > case.
> >
> > So I ran some basic performance tests on the l2fwd example with DPDK
> 1.7.1,
> > 1.8.0 and 2.0.0.
> > I used an Intel Xeon E5-2620 v3 CPU clocked down to 1.2 GHz in order to
> > ensure that the CPU and not the network bandwidth is the bottleneck.
> > I configured l2fwd to forward between two interfaces of an X540 NIC using
> > only a single CPU core (-q2) and measured the following throughput under
> > full bidirectional load:
> >
> >
> > Version TP [Mpps] Cycles/Pkt
> > 1.7.1 18.84 84.925690021
> > 1.8.0 16.78 95.351609058
> > 2.0.0 16.40 97.56097561
> >
> > DPDK 1.7.1 is about 15% faster in this scenario. The obvious suspect is the
> > new mbuf structure introduced in DPDK 1.8, so I profiled L1 cache misses:
> >
> > Version L1 miss ratio
> > 1.7.1 6.5%
> > 1.8.0 13.8%
> > 2.0.0 13.4%
> >
> >
> > FWIW the performance results with my packet generator on the same 1.2
> GHz
> > CPU core are:
> >
> > Version TP [Mpps] L1 cache miss ratio
> > 1.7 11.77 4.3%
> > 2.0 9.5 8.4%
Could you tell me how you got the L1 cache miss ratio? Perf?
> >
> >
> > The discussion about the original patch [2] which introduced the new mbuf
> > structure addresses this potential performance degradation and mentions
> that
> > it is somehow mitigated.
> > It even claims a 20% *increase* in performance in a specific scenario.
> > However, that doesn't seem to be the case for both l2fwd and my packet
> > generator.
> >
> > Any ideas how to fix this? A 25% loss in throughput prevents me from
> > upgrading to DPDK 2.0.0. I need the new lcore features and the 40 GBit
> > driver updates, so I can't stay on 1.7.1 forever.
Could you provide more information on how you run the l2fwd app,
in order to try to reproduce the issue:
- L2fwd Command line
- L2fwd initialization (to check memory/CPU/NICs)
Did you change the l2fwd app between versions? L2fwd uses simple rx on 1.7.1,
whereas it uses vector rx on 2.0 (enable IXGBE_DEBUG_INIT to check it).
Last question, I assume you use your traffic generator to get all those numbers.
Which packet format/size did you use? Does your traffic generator take into account the Inter-packet gap?
Thanks!
Pablo
> >
> > Paul
> >
> >
> > [1] https://github.com/emmericp/MoonGen
> > [2]
> http://comments.gmane.org/gmane.comp.networking.dpdk.devel/5155
>
>
>
> --
> Sincerely yours, Pavel Odintsov
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