On Mon, Sep 10, 2012 at 10:39:58PM +0200, Mark Nelson wrote: > On 09/10/2012 03:15 PM, Mike Ryan wrote: > > *Disclaimer*: these results are an investigation into potential > > bottlenecks in RADOS. I appreciate this investigation very much ! > > The test setup is wholly unrealistic, and these > > numbers SHOULD NOT be used as an indication of the performance of OSDs, > > messaging, RADOS, or ceph in general. > > > > > > Executive summary: rados bench has some internal bottleneck. Once that's > > cleared up, we're still having some issues saturating a single > > connection to an OSD. Having 2-3 connection in parallel alleviates that > > (either by having> 1 OSD or having multiple bencher clients). > > > > > > I've run three separate tests: msbench, smalliobench, and rados bench. > > In all cases I was trying to determine where bottleneck(s) exist. All > > the tests were run on a machine with 192 GB of RAM. The backing stores > > for all OSDs and journals are RAMdisks. The stores are running XFS. > > > > smalliobench: I ran tests varying the number of OSDs and bencher > > clients. In all cases, the number of PG's per OSD is 100. > > > > OSD Bencher Throughput (mbyte/sec) > > 1 1 510 > > 1 2 800 > > 1 3 850 > > 2 1 640 > > 2 2 660 > > 2 3 670 > > 3 1 780 > > 3 2 820 > > 3 3 870 > > 4 1 850 > > 4 2 970 > > 4 3 990 > > > > Note: these numbers are fairly fuzzy. I eyeballed them and they're only > > really accurate to about 10 mbyte/sec. The small IO bencher was run with > > 100 ops in flight, 4 mbyte io's, 4 mbyte files. > > > > msbench: ran tests trying to determine max throughput of raw messaging > > layer. Varied the number of concurrently connected msbench clients and > > measured aggregate throughput. Take-away: a messaging client can very > > consistently push 400-500 mbytes/sec through a single socket. > > > > Clients Throughput (mbyte/sec) > > 1 520 > > 2 880 > > 3 1300 > > 4 1900 > > > > Finally, rados bench, which seems to have its own bottleneck. Running > > varying numbers of these, each client seems to get 250 mbyte/sec up till > > the aggregate rate is around 1000 mbyte/sec (appx line speed as measured > > by iperf). These were run on a pool with 100 PGs/OSD. > > > > Clients Throughput (mbyte/sec) > > 1 250 > > 2 500 > > 3 750 > > 4 1000 (very fuzzy, probably 1000 +/- 75) > > 5 1000, seems to level out here > > -- > > 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 > > Hi guys, > > Some background on all of this: > > We've been doing some performance testing at Inktank and noticed that > performance with a single rados bench instance was plateauing at between > 600-700MB/s. 4-nodes with 10GbE interconnect; journals in RAM-Disk; replica=2 # rados bench -p pbench 20 write Maintaining 16 concurrent writes of 4194304 bytes for at least 20 seconds. sec Cur ops started finished avg MB/s cur MB/s last lat avg lat 0 0 0 0 0 0 - 0 1 16 288 272 1087.81 1088 0.051123 0.0571643 2 16 579 563 1125.85 1164 0.045729 0.0561784 3 16 863 847 1129.19 1136 0.042012 0.0560869 4 16 1150 1134 1133.87 1148 0.05466 0.0559281 5 16 1441 1425 1139.87 1164 0.036852 0.0556809 6 16 1733 1717 1144.54 1168 0.054594 0.0556124 7 16 2007 1991 1137.59 1096 0.04454 0.0556698 8 16 2290 2274 1136.88 1132 0.046777 0.0560103 9 16 2580 2564 1139.44 1160 0.073328 0.0559353 10 16 2871 2855 1141.88 1164 0.034091 0.0558576 11 16 3158 3142 1142.43 1148 0.250688 0.0558404 12 16 3445 3429 1142.88 1148 0.046941 0.0558071 13 16 3726 3710 1141.42 1124 0.054092 0.0559 14 16 4014 3998 1142.17 1152 0.03531 0.0558533 15 16 4298 4282 1141.75 1136 0.040005 0.0559383 16 16 4582 4566 1141.39 1136 0.048431 0.0559162 17 16 4859 4843 1139.42 1108 0.045805 0.0559891 18 16 5145 5129 1139.66 1144 0.046805 0.0560177 19 16 5422 5406 1137.99 1108 0.037295 0.0561341 2012-09-08 14:36:32.460311min lat: 0.029503 max lat: 0.47757 avg lat: 0.0561424 sec Cur ops started finished avg MB/s cur MB/s last lat avg lat 20 16 5701 5685 1136.89 1116 0.041493 0.0561424 Total time run: 20.197129 Total writes made: 5702 Write size: 4194304 Bandwidth (MB/sec): 1129.269 Stddev Bandwidth: 23.7487 Max bandwidth (MB/sec): 1168 Min bandwidth (MB/sec): 1088 Average Latency: 0.0564675 Stddev Latency: 0.0327582 Max latency: 0.47757 Min latency: 0.029503 Best Regards, -Dieter > Running multiple concurrent rados bench instances improves > performance, but only to a certain extent. The fastest throughput we've > seen so far is around 1160MB/s with 8 rados bench instances, 12 spinning > disks, and journals on SSDs. This is true regardless of the underlying > filesystem on the OSDs, though some hit the limits faster than others. > Some of the raw data is available here: > > https://docs.google.com/a/inktank.com/spreadsheet/ccc?key=0AnmmfpoQ1_94dDlmTHhvM19zd19tb05zbFVqZ2xSYXc#gid=0 > > To understand why we are plateauing, we wanted to investigate what > bottlenecks were present in rados bench and if there also were any > bottlenecks in the messenger code that might be limiting throughput. > Soon we should have a 36 drive setup in our SC847a chassis where we can > try to push things even further. :) > > Mark > -- > 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
