Re: [dpdk-dev] DPDK RSS support for ixgbevf PMD

["Ouyang, Changchun" <changchun.ouyang@intel.com>]

Hi

> -----Original Message-----
> From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com]
> Sent: Wednesday, December 17, 2014 4:47 PM
> To: Ouyang, Changchun; Thomas Monjalon
> Cc: dev@dpdk.org; Avi Kivity; Gleb Natapov
> Subject: Re: [dpdk-dev] DPDK RSS support for ixgbevf PMD
> 
> 
> On 12/17/14 03:03, Ouyang, Changchun wrote:
> > Hi ,
> >
> >> -----Original Message-----
> >> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Vlad Zolotarov
> >> Sent: Tuesday, December 16, 2014 11:36 PM
> >> To: Thomas Monjalon
> >> Cc: dev@dpdk.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.
> 

Yes you are right, it could be 2 queues, the actual queue number per VF depends on the number of VF:
VF number from 1~32:     4 queues per VF;
VF number from 33~64:   2 queues per VF;
The queue number is determined by the vf number at the pf init stage,
If pf setup 4 queues for each vf and distribute packets to 4 queues, but vf only poll 1 or 2 queue,
Then packets in other queues will be lost.
You can try to poll 4 queues firstly to debug your issue.
Thanks
Changchun