On Nov 8, 2012, at 9:39 AM, Mark Nelson <mark.nelson@xxxxxxxxxxx> wrote: > On 11/08/2012 07:55 AM, Atchley, Scott wrote: >> On Nov 8, 2012, at 3:22 AM, Gandalf Corvotempesta <gandalf.corvotempesta@xxxxxxxxx> wrote: >> >>> 2012/11/8 Mark Nelson <mark.nelson@xxxxxxxxxxx>: >>>> I haven't done much with IPoIB (just RDMA), but my understanding is that it >>>> tends to top out at like 15Gb/s. Some others on this mailing list can >>>> probably speak more authoritatively. Even with RDMA you are going to top >>>> out at around 3.1-3.2GB/s. >>> >>> 15Gb/s is still faster than 10Gbe >>> But this speed limit seems to be kernel-related and should be the same >>> even in a 10Gbe environment, or not? >> >> We have a test cluster with Mellanox QDR HCAs (i.e. NICs). When using Verbs (the native IB API), I see ~27 Gb/s between two hosts. When running Sockets over these devices using IPoIB, I see 13-22 Gb/s depending on whether I use interrupt affinity and process binding. >> >> For our Ceph testing, we will set the affinity of two of the mlx4 interrupt handlers to cores 0 and 1 and we will not using process binding. For single stream Netperf, we do use process binding and bind it to the same core (i.e. 0) and we see ~22 Gb/s. For multiple, concurrent Netperf runs, we do not use process binding but we still see ~22 Gb/s. > > Scott, this is very interesting! Does setting the interrupt affinity > make the biggest difference then when you have concurrent netperf > processes going? For some reason I thought that setting interrupt > affinity wasn't even guaranteed in linux any more, but this is just some > half-remembered recollection from a year or two ago. We are using RHEL6 with a 3.5.1 kernel. I tested single stream Netperf with and without affinity: Default (irqbalance running) 12.8 Gb/s IRQ balance off 13.0 Gb/s Set IRQ affinity to socket 0 17.3 Gb/s # using the Mellanox script When I set the affinity to cores 0-1 _and_ I bind Netperf to core 0, I get ~22 Gb/s for a single stream. >> We used all of the Mellanox tuning recommendations for IPoIB available in their tuning pdf: >> >> http://www.mellanox.com/related-docs/prod_software/Performance_Tuning_Guide_for_Mellanox_Network_Adapters.pdf >> >> We looked at their interrupt affinity setting scripts and then wrote our own. >> >> Our testing is with IPoIB in "connected" mode, not "datagram" mode. Connected mode is less scalable, but currently I only get ~3 Gb/s with datagram mode. Mellanox claims that we should get identical performance with both modes and we are looking into it. >> >> We are getting a new test cluster with FDR HCAs and I will look into those as well. > > Nice! At some point I'll probably try to justify getting some FDR cards > in house. I'd definitely like to hear how FDR ends up working for you. I'll post the numbers when I get access after they are set up. Scott -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
