On 8 Jul 2021, at 14:11, Stokes, Ian wrote:
>>> -----Original Message----- >>> From: Eelco Chaudron <[email protected]> >>> Sent: Thursday, July 8, 2021 11:48 AM >>> To: Ferriter, Cian <[email protected]> >>> Cc: [email protected]; [email protected]; [email protected]; Van >>> Haaren, Harry <[email protected]>; Amber, Kumar >>> <[email protected]>; Stokes, Ian <[email protected]> >>> Subject: Re: [v6 06/11] dpif-netdev: Add packet count and core id paramters >> for >>> study >>> >>> On 6 Jul 2021, at 15:11, Cian Ferriter wrote: >>> >>>> From: Kumar Amber <[email protected]> >>>> >>>> This commit introduces additional command line paramter >>>> for mfex study function. If user provides additional packet out >>>> it is used in study to compare minimum packets which must be processed >>>> else a default value is choosen. >>>> Also introduces a third paramter for choosing a particular pmd core. >>>> >>>> $ ovs-appctl dpif-netdev/miniflow-parser-set study 500 3 >>>> >>>> Signed-off-by: Kumar Amber <[email protected]> >>> >>> >>> When doing some testing I ran into another corner case. If I start one PMD >> with >>> packet count 1000, and then another with packet count 10. Both will use 10, >> as >>> the packet count value, as is stored globally. >> >> Valid corner case, good point, indeed the value is stored globally. >> >> The packet-count for study was designed/added as a way to avoid studying >> too many (overhead) or too few (inaccuracy) packets. I'm not sure how useful >> it *actually is* in real-world. >> >> Would documenting "the per packet count" is a global value, and parallel >> `study()` >> executions with differing packet counts will use the most recent count >> value" be >> acceptable? > > +1 to this, as a initial step I think this would be ok, it can change if > required in the future based on feedback from deployment. > We've seen similar approaches to features such as RXQ load balancing in OVS > using global values for sample time periods, I believe this is a similar case. As this looks similar, it’s not, as for load balancing it's a global configuration option. In this case, a specific PMD is configured, but it changes the behavior for all PMDs. I think, for now, we can do with documenting it. In the future, a solution could be to make it a per-thread variable. >> >> In any given scenario, I expect the "pkt_cnt" value to be the same for all >> PMD >> threads as variance in traffic is likely to be constant for all PMD-threads >> (particularly >> since auto-load-balancing of rxq/pmds is being improved). A single global >> value >> being >> used covers all my known use-cases. >> >> Thoughts? >> >>>> --- >>> < SNIP> >> _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
