Re: DPDK RSS support for ixgbevf PMD

[Vlad Zolotarov <vladz-RmZWMc9puTNJc61us3aD9laTQe2KTcn/@public.gmane.org>]

On 12/17/14 03:03, Ouyang, Changchun wrote:
> Hi ,
>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces-VfR2kkLFssw@public.gmane.org] On Behalf Of Vlad Zolotarov
>> Sent: Tuesday, December 16, 2014 11:36 PM
>> To: Thomas Monjalon
>> Cc: dev-VfR2kkLFssw@public.gmane.org; Avi Kivity; Gleb Natapov
>> Subject: Re: [dpdk-dev] DPDK RSS support for ixgbevf PMD
>>
>>
>> On 12/15/14 22:33, Thomas Monjalon wrote:
>>> 2014-12-15 21:11, Vladislav Zolotarov:
>>>> Hi,
>>>> I'm running an ixgbevf PMD on an AWS guests with extended networking
>>>> (SR-IOV functions of 82599 Intel's NIC) and noticed that even in the
>>>> current git tree there is no support for a multi-queue in this PMD:
>>>> reta size returned by rte_eth_dev_info_get() call is 0, while
>>>> max_rx_queues and max_tx_queues are both 4.
>>>>
>>>> Linux ixgbevf-2.15.3 driver on the other hand successfully
>>>> initializes 2 RSS queues: for some reason it always limits the number of
>> RSS queues by 2.
>>>> ixgbevf_main.c: line 2539
>>>> u16 rss = min_t(u16, num_online_cpus(), 2);
>>>>
>>>> The above is strange since if MRQE is set to 1010b there are 4 RSS
>>>> queues available which seems to be the case in my AWS Guest.
>>>>
>>>> However, let's get back to DPDK. As I've mentioned above the SR-IOV
>>>> function i have is RSS capable (to be 100% sure I've verified both
>>>> queues are receiving packets in a multi-socket TCP test). And it's a
>>>> shame I can't utilize it with a DPDK.
>>> Yes, it is not yet supported.
>>> But a patch was recently sent:
>>> 	http://dpdk.org/ml/archives/dev/2014-December/010028.html
>> Applying this patchset seems to break the NIC fast path functionality of a
>> AWS Guest NIC.
>> I'm still debugging it - will update u as soon as I have more specific info.

Hi, thanks for tips but I have a question below.

> Pls make sure enabling and using 4 queues on guest

Why should I enable all 4? Won't any number below or equal 4 work if (!) 
4 queues are available?
Note that there is a 82599 mode when only 2 RSS queues are available per 
VF: MRQE=1011b.

>   if you enable vf rss on host and if each vf has 4 queues,
> The packet could be received and put in any of 4 queues on guest depend on hash value of the packet.
> You could let packet IP address increased continuously and make those packets distribute to different queues.
>
> Thanks
> Changchun