[ovs-discuss] 100G with OvS

Joel Wirāmu Pauling joel at aenertia.net
Fri Nov 2 19:04:52 UTC 2018


DPDK. SRIOV and any sort of Smart NIC which removes or obfuscates the
generic kernel packet path from view have their place. But they are
all stop gap technologies IMNSHO.

eBPF + XDP  plugged into OVS is in my view the only truly useful use
case worth pursuing for SDN workload interaction.

If you need to switch faster you might as well get dedicated hardware
appliances; because for all practical purposes the Mellanox, Netronome
and VERY recent Intels offload mechanisms (including DPDK and SRIOV)
make the packet and flow processing path of the Kernel irrelevant .
You effectively have an entire GNU Linux/BSD stack there to provision
a very tiny bit of hardware that is actually doing anything ; and you
are not doing any meaningful interaction from the Kernel or
Application layers with said bit of hardware and you end up loosing
control and command and processing abilities. Black holes and edge
cases - leading to lower resiliency, feature disparity in the network
and increased management overhead in your scalable overlay fabric
forwarding path as a result.

There is a lot of VNF workloads that say they need  XYZ performance
metric to be met and there-fore need some $offload.

My Adjunct to that ; is that there are a lot of VNF workloads that
need to re-engineered to be a) Cloud Native b) apply newer or better
techniques for resilience in their packet paths.

Am not saying switching at 100G doesn't have it's place ; just that
for commodity cloud compute environments that place is questionable as
to it's current positioning on an overlay.


On Sat, 3 Nov 2018 at 05:04, Shivaram Mysore <shivaram.mysore at gmail.com> wrote:
>
> Thanks for sharing.  Yes - I have heard of some folks using Mellanox cards.  But, I was more curious about use of Intel FM10000 series - FM10420 and FM10840 chipset which Silicom and I think Lanner also has these cards with OVS.
>
> Thanks
>
> On Fri, Nov 2, 2018 at 4:35 AM <adamv0025 at netconsultings.com> wrote:
>>
>> Thank you very much for the slides,
>>
>> Hmm the presentation doesn’t actually have much detail on why the upper bound is ~30G (I guess per port), well with 6 cores anyways, using the slow x86 path.
>>
>>
>>
>> So is the point you’re trying to make that above 40G per port one needs to enter the realm of “smart” NICs please
>>
>> If true then I’d be interested in how do these differ from the say P4/Tofino like chips.
>>
>> I guess that’s the realm where I’d be limited in terms of available OVS features to only those for which a HW acceleration is available on the NIC –is that assumption correct please?
>>
>>
>>
>> adam
>>
>>
>>
>> netconsultings.com
>>
>> ::carrier-class solutions for the telecommunications industry::
>>
>>
>>
>> From: Joel Wirāmu Pauling [mailto:joel at aenertia.net]
>> Sent: Friday, November 02, 2018 9:40 AM
>> To: adamv0025 at netconsultings.com
>> Cc: Shivaram Mysore; ovs-discuss at openvswitch.org
>> Subject: Re: [ovs-discuss] 100G with OvS
>>
>>
>>
>> Have a look at :
>>
>>
>>
>> https://m.youtube.com/watch?v=MglrK-JTiqc
>>
>>
>>
>> Disclaimer I worked for Nuage at the time that was done, and work for Redhat now.
>>
>>
>>
>>
>>
>>
>>
>> On Fri, 2 Nov 2018, 22:23 <adamv0025 at netconsultings.com wrote:
>>
>> > bounces at openvswitch.org] On Behalf Of Joel Wiramu Pauling
>> > Sent: Thursday, November 01, 2018 10:29 PM
>> >
>> > Currently - doing slow-path through commodity x86 silicon you are pretty
>> > much capped at 40gbit; so beyond a few use cases where you are say
>> > writting to an NVME array directly within minimal CPU interaction 100G to
>> > nodes is relatively limited. I've read several relatively good analysis
>> which
>> > indicate that we are close to physical limits when we hit around 130Gbit
>> with
>> > Ethernet ; but currently 40Gbit through existing x86_64 architectures is
>> about
>> > spot on.
>> >
>> Hi Joel,
>>
>> Thank you very much for the info,
>>
>> I assume this limit is per physical NIC is that the case please?
>> (I'm wondering if I'd get a ~100Gbps worth of throughput (100G in + 100G
>> out) through the system as a whole -i.e. multiple interfaces, essentially
>> turning it into an OVS-router.
>>
>> Would you please share what is the limiting factor?
>> (just found that PCIe 3.0 x16 should be capped at 126.075Gbps usable BW;
>> DDR3-2133 @ ~136.5Gbps and Intel® Xeon® Processor E5 Family it's 372.8 Gbps)
>>
>> Thakn you very much
>>
>> adam
>>
>> netconsultings.com
>> ::carrier-class solutions for the telecommunications industry::


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