On 9/5/17, 2:01 AM, "Yuanhan Liu" <[email protected]> wrote:

    On Fri, Sep 01, 2017 at 10:35:51PM +0000, Darrell Ball wrote:
    > 
    > 
    > On 8/31/17, 3:13 AM, "Yuanhan Liu" <[email protected]> wrote:
    > 
    >     On Wed, Aug 30, 2017 at 07:28:01PM +0000, Darrell Ball wrote:
    >     >     
    >     >     [Finn]
    >     >     
    >     >     I think we should not further intermix the rxqs distributed to 
different pmd's, other than initially configured, when setting up hw-offload. 
If we make a round-robin distribution of the rxqs, a different pmd will most 
likely receive the hw-offloaded packets - not the same pmd that ran the 
slow-path originally creating the flow.
    >     >     
    >     >     It is usual to optimize caches etc. per pmd and that would not 
work then. Maybe the further processing of the hw-offloaded packets does not 
need these optimizations at the moment, however, IMHO I think we would be 
better off using the first proposal above (use the same rxq as the one creating 
the flow).
    >     > 
    >     > [Darrell] Several ideas have some validity.
    >     >                  However, this sounds reasonable and simple and we 
could revisit as needed.
    >     >                  What do you think Yuanhan ?
    >     
    >     Just want to make sure we are on the same page: do you mean the 
original
    >     solution/workaround I mentioned in the cover letter: record the rxq at
    >     recv and pass it down to flow creation?
    >     
    >     If so, I'm okay with it.
    > 
    > [Darrell]
    > This is the relevant part from the cover letter:
    > 
    > “One possible
    >  solution is to record the rxq and pass it down to the flow creation
    >  stage. It would be much better, but it's still far away from being 
perfect.
    >  Because it might have changed the steering rules stealthily, which may
    >  break the default RSS setup by OVS-DPDK.”
    > 
    > This is a reasonable first cut.
    > However, the flows installed are masked flows but the associated packets 
would ‘normally’ end up on multiple
    > PMDs due to RSS, right ?
    
    Why it's "multiple PMDs due to RSS"? Isn't RSS for distributing packets
    to multiple RX queues inside the NIC?

[Darrell] I was referring to the general case of using the distribution across 
queues to
distribute work to different PMDs.

    
        --yliu
    
    > But for HWOL, we specify ‘the queue’ to be the one we receive the first 
packet from. 
    > This is what I was getting at b4. So, future workarounds would be 
‘auto-splitting flows’ across queues, user specified flow->queue
    > associations etc
    > 
    > 
    > 
    > 
    > 
    >     
    >           --yliu
    >     
    > 
    > 
    > 
    > 
    > 
    

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