On 13 September 2012 08:25, Mark Nelson <mark.nelson@xxxxxxxxxxx> wrote: > On 09/12/2012 03:08 PM, Dieter Kasper wrote: >> >> 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 >> > > Well look at that! :) Now I've gotta figure out what the difference is. > How fast are the CPUs in your rados bench machine there? > > Also, I should mention that at these speeds, we noticed that crc32c > calculations were actually having a pretty big effect. Turning them off > gave us a 10% performance boost. We're looking at faster implementations > now. > > > 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 Hi Mark If using primarily Intel machines that are Nahalem or better (I would imagine most boxes running Ceph would fit this category) then consider using the Intel CRC32 instructions. Most of the work to use them is laid out here: http://www.drdobbs.com/parallel/fast-parallelized-crc-computation-using/229401411 -- CTO | Orion Virtualisation Solutions | www.orionvm.com.au Phone: 1300 56 99 52 | Mobile: 0428 754 846 -- 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
