[ovs-dev] [PATCH v3] dpif-netdev: Fix insertion probability

Ben Pfaff blp at ovn.org
Tue Jul 11 20:05:11 UTC 2017


On Fri, Jun 23, 2017 at 04:59:40PM +0100, Kevin Traynor wrote:
> On 06/23/2017 04:31 PM, Ciara Loftus wrote:
> > emc_conditional_insert uses pmd->last_cycles and the packet's RSS hash
> > to generate a random number used to determine whether or not an emc
> > entry should be inserted. This works for single-packet bursts as
> > last_cycles is updated for each burst. However, for bursts > 1 packet,
> > where the packets in the batch generate the same RSS hash,
> > pmd->last_cycles remains constant for the entire burst also, and thus
> > cannot be used as a random number for each packet in the burst.
> > 
> > This commit replaces the use of pmd->last_cycles with random_uint32()
> > for this purpose and subsequently fixes the behavior of the
> > emc_insert_inv_prob setting for high-throughput (large bursts)
> > single-flow cases.
> > 
> 
> Thanks for the fix.
> Acked-by: Kevin Traynor <ktraynor at redhat.com>
> 
> I also ran a quick test (on V2)
> Tested-by: Kevin Traynor <ktraynor at redhat.com>

Thanks Ciara, Kevin, Darrell.  I applied this to master.


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