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: Thursday, December 18, 2014 6:34 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 12/18/14 03:32, Ouyang, Changchun wrote:
> > 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.
> 
> Sure. When I hardcoded the queues number to 4 all works like a charm.
> The problem is that we can't leave it this way. I've posted some comments to
> your patches (0 and 5). Since I've joined the list after the patches have been
> sent I had to paste the patches bodies into my email and they will most like
> not appear in the thread of the original series.
> I hope this won't be a big problem... ;)
> 
Yes, I have seen your comments there, and respond it already, let's use that thread to discuss from now on.

Thanks
Changchun