On Tue, Jul 15, 2014 at 03:40:56PM +0000, Zhou, Danny wrote: > > > -----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.
Cool, good info...thanks! -- John W. Linville Someday the world will need a hero, and you linville at tuxdriver.com might be all we have. Be ready.
