> -----Original Message----- > From: John W. Linville [mailto:linville at tuxdriver.com] > Sent: Tuesday, July 15, 2014 10:01 PM > To: Neil Horman > Cc: Zhou, Danny; dev at dpdk.org > Subject: Re: [dpdk-dev] [PATCH v2] librte_pmd_packet: add PMD for > AF_PACKET-based virtual devices > > On Tue, Jul 15, 2014 at 08:17:44AM -0400, Neil Horman wrote: > > On Tue, Jul 15, 2014 at 12:15:49AM +0000, Zhou, Danny wrote: > > > According to my performance measurement results for 64B small > > > packet, 1 queue perf. is better than 16 queues (1.35M pps vs. 0.93M > > > pps) which make sense to me as for 16 queues case more CPU cycles > > > (16 queues' 87% vs. 1 queue' 80%) in kernel land needed for > > > NAPI-enabled ixgbe driver to switch between polling and interrupt > > > modes in order to service per-queue rx interrupts, so more context > > > switch overhead involved. Also, since the > > > eth_packet_rx/eth_packet_tx routines involves in two memory copies > > > between DPDK mbuf and pbuf for each packet, it can hardly achieve > > > high performance unless packet are directly DMA to mbuf which needs ixgbe > driver to support. > > > > I thought 16 queues would be spread out between as many cpus as you > > had though, obviating the need for context switches, no? > > I think Danny is testing the single CPU case. Having more queues than CPUs > probably does not provide any benefit. > > It would be cool to hack the DPDK memory management to work directly out of > the > mmap'ed AF_PACKET buffers. But at this point I don't have enough knowledge of > DPDK internals to know if that is at all reasonable... > > John > > P.S. Danny, have you run any performance tests on the PCAP driver?
No, I do not have PCAP driver performance results in hand. But I remember it is less than 1M pps for 64B. > > -- > John W. Linville Someday the world will need a hero, and you > linville at tuxdriver.com might be all we have. Be ready.
