Re: [dpdk-dev] [PATCH] fm10k: conditionally disable RSS during device initialization

["Chen, Jing D" <jing.d.chen@intel.com>]

Thomas,

We've agreed offline that the patch works without side effect.
Please kindly apply if possible.

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> Sent: Thursday, March 31, 2016 9:57 PM
> To: dev@dpdk.org
> Cc: Michael Frasca <michael.frasca@oracle.com>; Chen, Jing D
> <jing.d.chen@intel.com>
> Subject: Re: [dpdk-dev] [PATCH] fm10k: conditionally disable RSS during
> device initialization
> 
> Please, anyone to confirm that the patch is valid and must be applied?
> This discussion shows some doubts.
> 
> 
> 2016-03-24 13:35, Michael Frasca:
> > Jing,
> >
> > Thanks for your assistance. The experiment that you have built should
> > allow you to observe the bug. In [5], I would expect that queue 0
> > receives roughly 1/4 of the packets that you sending, assuming the
> > input packets have varied IP addresses. Can you measure what % of
> > packets are actually being received in this single queue setup (after first
> running a 4-queue setup)?
> >
> > When trying to running with only one RX queue, the fm10k retains the
> > same RSS hash function and redirection table that was configured from
> > a previous run. As a result, some packets are still being directed to
> > other receive queues. I have confirmed this by polling the queue
> > specific stats, which I retrieved via rte_eth_xstats_get().
> >
> > Looking at fm10k_dev_rss_configure(), one should see that there is no
> > modification of fm10k registers when nb_rx_queues == 1. As far as I
> > can tell, this is the reason that only a certain partition of packets
> > are being receive in a single queue setup (after first running a multi-queue
> configuration).
> >
> > I am unable to access my development environment today, but if you
> > need, I can later craft a patch to l3fwd that shows the measurement of
> > packets received at each queue.
> >
> > Thanks,
> > Mike
> >
> >
> > > On Mar 24, 2016, at 2:40 AM, Chen, Jing D <jing.d.chen@intel.com> wrote:
> > >
> > > Hi, Frasca,
> > >
> > >
> > >
> > >> -----Original Message-----
> > >> From: Michael Frasca [mailto:michael.frasca@oracle.com
> > >> <mailto:michael.frasca@oracle.com>]
> > >> Sent: Wednesday, March 23, 2016 9:43 PM
> > >> To: Chen, Jing D
> > >> Cc: dev@dpdk.org <mailto:dev@dpdk.org>
> > >> Subject: Re: [PATCH] fm10k: conditionally disable RSS during device
> > >> initialization
> > >>
> > >> Hi Jing,
> > >>
> > >> I ran into this issue while trying to run experiments with
> > >> different RSS configurations (no RSS being one cases). It is not
> > >> clear to me that setting this register to zero is the best way to disable
> RSS.
> > >>
> > >> After digging further, I have a theory that I'm having this issues
> > >> because I've only attached my DPDK application to SR-IOV ports. In
> > >> fm10k_dev_dglort_map_configure(), I see that 'RSS Length' is set
> > >> for the DGLORT decoder. However, it appears that this is only
> > >> invoked for physical functions.
> > >>
> > >> Could this be my problem? Is it required that I bind to the
> > >> physical function if I want to properly manipulate RSS?
> > >>
> > >> Thanks,
> > >> Mike
> > >>
> > > I don't know exactly what problem you ran into. I think we needn't
> > > worry about those DGLORT setting when using VF device.
> > >
> > > I've followed steps to use SRIOV device with RSS enabled and
> > > disabled, both are worked well from my side after applying your patch.
> Below is my setup.
> > >
> > > 1. PF with Linux driver "fm10k-next_0.19.3".
> > > 2. DPDK with latest code from master branch, apply your patch.
> > > 3. Use 1 VF device created by kernel driver.
> > > 4. use l3fwd with " ./examples/l3fwd/build/l3fwd -c fc -n 4 -- -p 0x1 --
> config="(0,0,2),(0,1,2),(0,2,3),(0,3,3)""
> > >    with RSS enabled. After sending packets, I can see all 4 queues received
> packets.
> > > 5. use l3fwd with " ./examples/l3fwd/build/l3fwd -c fc -n 4 -- -p 0x1 --
> config="(0,0,2)""
> > >    with RSS disabled. After sending packets, I can see queue 0 received
> packets.
> > >
> > > Can you explain what actual problem is?
> > > We can talk offline.
> >
>