On Thu, Nov 8, 2012 at 7:02 PM, Atchley, Scott <atchleyes@xxxxxxxx> wrote: > On Nov 8, 2012, at 10:00 AM, Scott Atchley <atchleyes@xxxxxxxx> wrote: > >> 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. > Did you tried Mellanox-baked modules for 2.6.32 before that? > Note, I used hwloc to determine which socket was closer to the mlx4 device on our dual socket machines. On these nodes, hwloc reported that both sockets were equally close, but a colleague has machines where one socket is closer than the other. In that case, bind to the closer socket (or to cores within the closer socket). > >> >>>> 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 -- 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
