[ovs-dev] [PATCH v10 0/5] dpcls func ptrs & optimizations

Ilya Maximets i.maximets at samsung.com
Thu Jul 11 14:13:43 UTC 2019

On 09.07.2019 15:34, Harry van Haaren wrote:
> Hey All,
> Here a v10 of the DPCLS Function Pointer patchset, as has been
> presented at OVS Conf in Nov '18, and discussed on the ML since then.
> I'm aware of the soft-freeze for 2.12, I feel this patchset has had
> enough reviews/versions/testing to be merged in 2.12.
> Thanks Ilya and Ian for review comments on v9, they should all be addressed
> in this v10. 
> Thanks Malvika Gupta for testing (Tested-by tag added to patches) and also
> for reporting ARM performance gains, see here for details:
> https://mail.openvswitch.org/pipermail/ovs-dev/2019-June/360088.html
> Regards, -Harry

Hi, Harry.
Thanks for working on this.

I performed some tests with this version in my usual PVP with bonded PHY
setup and here are some observations:

* Bug that redirected packets to wrong rules is gone. At least I can't
  catch it in my testing anymore. Assuming it's fixed now.

* dpcls performance boost for 512B packets is around 12% in compare with
  current master.

Few remarks about the test scenario:
All packets mostly goes through the NORMAL action with vlan push/pop.
Packets that goes from VM to balanced-tcp bonded PHY goes through
recirculation. Datapath flows for them looks like this:

Before recirculation:

After recirculation:

I have 256 flows in datapath for different 'dp_hash'es.

So, even if the number of ipv4 flows is as high as 256K, I have about ~270 datapath
flows in dpcls. (This gives a huge advantage to dpcls over EMC and SMC).

All the flows fits into 5+1 case, i.e. optimized function 
dpcls_subtable_lookup_mf_u0w5_u1w1 used.

Most interesting observation:

* New version of dpcls lookup outperforms SMC in this setup even on
  relatively small number of flows. With 8K flows dpcls faster than SMC
  by 1.5% and by 5.7% with 256K flows.
  Of course, SMC is 10% faster than dpcls with 8 flows, but it's not very
  interesting because no-one can beat EMC in this area.

I'd like to read the code more carefully tomorrow and probably give some
more feedback.

Best regards, Ilya Maximets.

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