Re: [dpdk-dev] [PATCH v3 0/6] Enable VF RSS for Niantic

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

Hi,

> -----Original Message-----
> From: Vlad Zolotarov [mailto:vladz@cloudius-systems.com]
> Sent: Wednesday, December 24, 2014 6:49 PM
> To: Ouyang, Changchun; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v3 0/6] Enable VF RSS for Niantic
> 
> 
> On 12/24/14 07:22, Ouyang Changchun wrote:
> > This patch enables VF RSS for Niantic, which allow each VF having at most 4
> queues.
> > The actual queue number per VF depends on the total number of pool,
> > which is determined by the total number of VF at PF initialization
> > stage and the number of queue specified in config:
> > 1) If the number of VF is in the range from 1 to 32 and the number of
> > rxq is 4('--rxq 4' in testpmd), then there is totally 32
> > pools(ETH_32_POOLS), and each VF have 4 queues;
> >
> > 2)If the number of VF is in the range from 33 to 64 and the number of
> > rxq is 2('--rxq 2' in testpmd), then there is totally 64
> > pools(ETH_64_POOLS), and each VF have 2 queues;
> >
> > On host, to enable VF RSS functionality, rx mq mode should be set as
> > ETH_MQ_RX_VMDQ_RSS or ETH_MQ_RX_RSS mode, and SRIOV mode
> should be activated(max_vfs >= 1).
> > It also needs config VF RSS information like hash function, RSS key, RSS key
> length.
> >
> > The limitation for Niantic VF RSS is:
> > the hash and key are shared among PF and all VF, the RETA table with
> > 128 entries are also shared among PF and all VF. So it is not good
> > idea to query the hash and reta content per VF on guest, instead, it makes
> sense to query them on host(PF).
> >
> > v3 change:
> >    - More cleanup;
> 
> This series is still missing the appropriate patches in the
> rte_eth_dev_info_get() flow to return a reta_size for a VF device; and to
> rte_eth_dev_rss_reta_query() in the context of a VF device (I haven't
> noticed the initialization of a
> dev->dev_ops->reta_query for the VF device in this series).
> 
> Without these code bits it's impossible to work with the VF devices in the RSS
> context the same way we work with the PF devices. It means that we'll have
> to do some special branching to handle the VF device and this voids the
> whole meaning of the framework which in turn is very unfortunate.
> 
Again pls try to query reta content on pf/host, this is due to hw limitation,
It don't affect any functionality, just the querying is special.
Before this patch, customer often was notified Niantic can't support vf rss,
But with lots of experiments and find that it still has limited vf rss functionality.
Even on that, linux ixgbe driver has at most 2 queues per vf,
But the dpdk could enable 4 queues per vf.
In summary, dpdk could support vf rss on Niantic with at most 4 queues per vf,
but the querying of reta is very limited due to the HW limitation.  
Hope you are on the same page now.

Thanks
Changchun