Re: [dpdk-dev] DPDK qos support for 40G port

[Kevin Yan <Kevin.Yan@mavenir.com>]

Hi Cristian,
Sorry to bother again, could you give suggestions/hints of code change to support single 40G port?  Because  in our setup, we will use single 40G port (Intel XL710) as the network interface.

Or is there any workaround to bypass the limitation?(we are not willing to use 4*10G setup)

Thanks.

-----Original Message-----
From: Dumitrescu, Cristian [mailto:cristian.dumitrescu@intel.com]
Sent: Friday, August 04, 2017 5:57 PM
To: Kevin Yan <Kevin.Yan@mavenir.com>; dev@dpdk.org
Subject: RE: DPDK qos support for 40G port

Hi Kevin,

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Kevin Yan
> Sent: Friday, August 4, 2017 2:55 AM
> To: dev@dpdk.org
> Subject: [dpdk-dev] DPDK qos support for 40G port
>
> Hi,
>                 I have  a question about dpdk qos feature, in
> rte_sched.h,

<snip>...

>                 rate is type of uint32_t, but if physical port rate is
> 40G bit/s, which is 5G byte/s, 5G already exceed the max value of
> uint32_t, so I doult that 40G is not supported by dpdk qos lib, or any error of my understanding?
>

Yes, your understanding is correct, currently the port rate in bytes per second needs to be represented as 32-bit number.

So, we can currently do single port with 10GbE and 25GbE rate, but not single port of 40GbE or 100GbE. Please note that we can do 40GbE as 4 ports of 10GbE each, which is a very common configuration for 40GbE.

This limitation is not trivial to remove, i.e. more code is needed to remove this limitation than just changing the rate data type to uint64_t.

Thanks for your feedback. Good to know that we should upgrade this library to support 40GbE rates sooner rather than later.

>                 Thanks and waiting for your reply!
>
>
> BRs,
> Kevin
>

Regards,
Cristian

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