[ovs-dev] [PATCH v2 0/8] OVS-DPDK flow offload with rte_flow

Darrell Ball dball at vmware.com
Wed Sep 13 04:14:48 UTC 2017



On 9/7/17, 6:59 PM, "Yuanhan Liu" <yliu at fridaylinux.org> wrote:

    On Thu, Sep 07, 2017 at 06:52:49PM +0000, Patil, Harish wrote:
    > >Hi all,
    > >
    > >Can you please confirm that you are supporting offloading of both the EMC
    > >flows and DPCLs (megaflows) here, i.e. OVS would skip hash table lookups
    > >in both the cases if UFID is provided in the MBUF. Assuming that is
    > >correct, when a match is found in dpcls, does OVS insert that new flow
    > >back into the EMC cache?
    > >
    > >Thanks,
    > >Harish
    > >
    > >[Finn]
    > >Yes, you are correct. Once the megaflow is offloaded into NIC, using the
    > >flow UFID,
    > >the EMC and megaflow cache (dpcls) is skipped when a UFID is received in
    > >mbuf. When
    > >receiving these pre-classified packets the EMC is not needed. However,
    > >the initial packet
    > >creating the megaflow (and then also creates the NIC rte flow), will be
    > >inserted into EMC.
    > 
    > [Harish] Thanks Finn for confirming the behavior.
    > 
    > 
    > >But, new flows that would use the same megaflow, but would create a
    > >different EMC entry,
    > >will not be inserted/created in EMC when offloaded by NIC.
    > 
    > [Harish I did not fully understand this part. Can you pls elaborate and
    > possibly with an example?
    
    It's megaflow cache being offloaded. And the EMC is skipped completely
    once there are flow mark in the recved pkts. Thus, it doesn't matter
    whether EMC will be inserted back.
    
    Talking about that, I probably need move the "mark -> flow" code to
    dpcls but not in emc_processing. Darrel, just let me know which one
    you prefer.

[Darrell] sorry, too many e-mails.
                 I had some related comments to share, but yes.
                Probably fast_path_processing().


    
    > [Harish] I have another question:
    > There was a patch series (11/11) submitted regarding offloading dpcls from
    > Shachar Beiser.
    > 
    > [ovs-dev] [PATCH 00/11] Data Path Classifier Offloading
    > ..
    > ..
    > [ovs-dev] [PATCH 11/11] ovs/dp-cls: inserting rule to HW from	offloading
    > thread context.
    > 
    > 
    > This does not use RTE_FLOW filtering framework. I don’t know status of
    > this patch series.
    > But this is very similar to what is being achieved with your current patch
    > series using RTE_FLOW.
    > Which one will be accepted in the end in the mainline OVS branch?
    
    As it's been stated in the first sentence of my cover letter, it's a
    joint work from Mellanox and Napatech. Shachar (who is from Mellanox)
    does't have time to work on this project anymore, leaving me (who is
    also from Mellanox) to continue the work. And then my choice was to
    continue it based on what Napatech already had, for a simple reason:
    it's simpler.
    
    OTOH, do you see anything missing in this patchset, comparing the one
    from Shachar?
    
    	--yliu
    



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