[Cake] [Bloat] are anyone playing with dpdk and vpp?

Dave Taht dave.taht at gmail.com
Wed Apr 27 15:45:48 EDT 2016

On Wed, Apr 27, 2016 at 12:32 PM, Stephen Hemminger
<stephen at networkplumber.org> wrote:
> DPDK gets impressive performance on large systems (like 14M packets/sec per
> core), but not convinced on smaller systems.

My take on dpdk has been mostly that it's a great way to heat data
centers. Still I would really like to see these advanced algorithms
(cake, pie, fq_codel, htb) tested on it at these higher speeds.

And I still have great hope for cheap, FPGA-assisted designs that
could one day be turned into asics, but not as much as I did last year
when I first started fiddling with the meshsr onenetswitch. I really
wish I could find a few good EE's to tackle making something fq_codel
like work on the netfpga project, the proof of concept verilog already
exists for DRR and AQM technologies.

> Performance depends on having good CPU cache. I get poor performance on Atom
> etc.

I had hoped that the rangeley class atoms would do better on dpdk, as
they do I/O direct to cache. I am not sure which processors that is
actually in, anymore.

> Also driver support is limited (mostly 10G and above)

Well, as we push end-user class devices to 1GigE, we are having issues
with overuse of offloads to get there, and in terms
of PPS, certainly pushing small packets is becoming a problem, on
ethernet and wifi. I would like to see a 100 dollar router that could
do full PPS at that speed, feeding fiber and going over 802.11ac, and
we are quite far from there. I see, for example, that meraki is using
click (I think) to push more processing into userspace.

Also the time for a packet to transit linux from read to write is
"interesting". Last I looked it was something like 42 function calls
in the path to "get there", and some of my benchmarks on both the c2
and apu2 are showing that that time is significant enough for fq_codel
to start kicking in to compensate. (which is kind of cool to see the
packet processing adapt to the cpu load, actually - and I still long
for timestamping on rx directly to adapt ever better)

I have also acquired a mild dislike for seeing stuff like this:

where the tx and rx rings are cleaned up in the same thread and there
is only one interrupt line for both.

  51:         18      59244     253350     314273   PCI-MSI
1572865-edge      enp3s0-TxRx-0
  52:          5     484274     141746     197260   PCI-MSI
1572866-edge      enp3s0-TxRx-1
  53:          9     152225      29943     436749   PCI-MSI
1572867-edge      enp3s0-TxRx-2
  54:         22      54327     299670     360356   PCI-MSI
1572868-edge      enp3s0-TxRx-3
  56:     525343     513165    2355680     525593   PCI-MSI
2097152-edge      ath10k_pci

and the ath10k only uses one interrupt. Maybe I'm wrong on my
assumptions, I'd think in today's multi-core environment that
processing tx and rx separately might be a win. (?)

I keep hoping for on-board assist for routing table lookups on
something - your classic cam - for example. I saw today that there has
been some work on getting source specific routing into dpdk, which
makes me happy -


which is, incidentally, where I found the reference to the vpp stuff.


> On Wed, Apr 27, 2016 at 12:28 PM, Aaron Wood <woody77 at gmail.com> wrote:
>> I'm looking at DPDK for a project, but I think I can make substantial
>> gains with just AF_PACKET + FANOUT and SO_REUSEPORT.  It's not clear to my
>> yet how much DPDK is going to gain over those (and those can go a long way
>> on higher-powered platforms).
>> On lower-end systems, I'm more suspicious of the memory bus (and the cache
>> in particular), than I am the raw CPU power.
>> -Aaron
>> On Wed, Apr 27, 2016 at 11:57 AM, Dave Taht <dave.taht at gmail.com> wrote:
>>> https://fd.io/technology seems to have come a long way.
>>> --
>>> Dave Täht
>>> Let's go make home routers and wifi faster! With better software!
>>> http://blog.cerowrt.org
>>> _______________________________________________
>>> Bloat mailing list
>>> Bloat at lists.bufferbloat.net
>>> https://lists.bufferbloat.net/listinfo/bloat
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Dave Täht
Let's go make home routers and wifi faster! With better software!

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