[ovs-dev] [PATCH 1/5] dpif-netdev: Skip EMC lookup when EMC is disabled.

Darrell Ball dball at vmware.com
Wed May 17 02:49:53 UTC 2017


I found 4-5% throughput improvement when emc is disabled and it is a simple change
Thanks for adding this.

Acked-by: Darrell Ball dlu998 at gmail.com



On 4/13/17, 11:30 AM, "ovs-dev-bounces at openvswitch.org on behalf of Bodireddy, Bhanuprakash" <ovs-dev-bounces at openvswitch.org on behalf of bhanuprakash.bodireddy at intel.com> wrote:

    >On 04/13/2017 07:11 PM, Kevin Traynor wrote:
    >> On 03/12/2017 05:33 PM, Bhanuprakash Bodireddy wrote:
    >>> Conditional EMC insert patch gives the flexibility to configure the
    >>> probability of flow insertion in to EMC. This also allows an option
    >>> to entirely disable EMC by setting 'emc-insert-inv-prob=0' which can
    >>> be useful at large number of parallel flows.
    >>>
    >>> This patch skips EMC lookup when EMC is disabled. This is useful to
    >>> avoid wasting CPU cycles and also improve performance considerably.
    >>>
    >>
    >> LGTM. How much does this improve performance?
    
    I found  significant performance improvement when testing with few hundred streams.  I remember the improvement was  ~800kpps  with smaller packets. This is for the reason that emc_lookup() invokes expensive memcmp() to compare the netdev_flow_key in EMC and it takes up significant cycles. Longer the 'key', worse the performance.  
    
    >Ack for the series,
    >Acked-by: Kevin Traynor <ktraynor at redhat.com>
    
    Thanks kevin for the review and Acks.
    
    Regards,
    Bhanuprakash. 
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