From: EXT Bala Manoharan [mailto:[email protected]] Sent: Friday, March 04, 2016 2:39 PM To: Tilli, Juha-Matti (Nokia - FI/Espoo) <[email protected]> Cc: Savolainen, Petri (Nokia - FI/Espoo) <[email protected]>; LNG ODP Mailman List <[email protected]> Subject: Re: [lng-odp] [API-NEXT PATCH 1/2] api: pktio: add recv from multiple queues with tmo
On 4 March 2016 at 17:47, Tilli, Juha-Matti (Nokia - FI/Espoo) <[email protected]> wrote: Hi, The current algorithm indeed is unfair, because queue 0 has the highest priority. There are at least two solutions to this: 1. Leave the priority order unspecified 2. Specify that queues are checked in the order they appear in the array I kind of like solution (2), because it allows the application to behave in a round-robin manner by altering the order of the queues between the calls: - odp_pktin_recv_mq_tmo({q1, q2, q3, q4}, …) - odp_pktin_recv_mq_tmo({q2, q3, q4, q1}, …) - odp_pktin_recv_mq_tmo({q3, q4, q1, q2}, …) - odp_pktin_recv_mq_tmo({q4, q1, q2, q3}, …) … Then essentially the priority of all queues averages out to have approximately the same average priority. So, you should perhaps consider in the API spec that the priority order could be defined to be 0, 1, 2, …. I cannot foresee any implementation which would use a different priority order. Agreed. We can improve the documentation to specify that priority is in the order of input queue in the array with '0' being highest priority. Regards, Bala I'd add in a next step (if needed and feasible). The algorithm above works for fairness regardless if the first or any other queue has highest priority. I'd like to first get verification that strict priority specification would not cause performance issues. E.g. on some platform it may optimize performance, if the next recv_mq() call continues from the same queue the last finished, or any other relation between queues (e.g. if two queues point to related interfaces, handle those together: first all netmap interfaces, then all sockets, ...). -Petri _______________________________________________ lng-odp mailing list [email protected] https://lists.linaro.org/mailman/listinfo/lng-odp
