[dpdk-dev] [PATCH v3] net/mlx5: relaxed ordering for multi-packet RQ buffer refcnt

[Honnappa Nagarahalli]

<snip>

> > > Subject: RE: [dpdk-dev] [PATCH v3] net/mlx5: relaxed ordering for
> > > multi- packet RQ buffer refcnt
> > >
> > > Hi Phil Yang, we noticed that this patch gives us 10% of performance
> > > degradation on ARM.
> > > x86 seems to be unaffected though. Do you know what may be the
> > > reason of this behavior?
> >
> > Hi Alexander,
> >
> > Thanks for your feedback.
> > This patch removed some expensive memory barriers on aarch64, it
> > should get better performance.
> > I am not sure the root cause of this degradation now, I will start the
> > investigation. We can profiling this issue together.
> > Could you share your test case(including your testbed configuration) with
> us?
> >
> > Thanks,
> > Phil
> 
> I'm surprised too, Phil, but looks like it is actually making things worse. I used
> Connect-X 6DX on aarch64:
> Linux dragon71-bf 5.4.31-mlnx.15.ge938819 #1 SMP PREEMPT Thu Jul 2
> 17:01:15 IDT 2020 aarch64 aarch64 aarch64 GNU/Linux Traffic generator
> sends 60 bytes packets and DUT executes the following command:
> arm64-bluefield-linuxapp-gcc/build/app/test-pmd/testpmd -n 4  -w
> 0000:03:00.1,mprq_en=1,rxqs_min_mprq=1  -w
> 0000:03:00.0,mprq_en=1,rxqs_min_mprq=1 -c 0xe  -- --burst=64 --
> mbcache=512 -i  --nb-cores=1  --rxq=1 --txq=1 --txd=256 --rxd=256  --auto-
> start --rss-udp Without a patch I'm getting 3.2mpps, and only 2.9mpps when
> the patch is applied.
You are running on A72 cores, is that correct?

> 
> Regards,
> Alex