Ceph » RADOS

It would be useful for testing OSD caching behavior if rados bench would respect --max-objects parameter. It seems to be parsed but not used. As you can see below, the command accepts "--max-objects 100" but reads 800 objects.

[root@ceph1 ~]# rados bench -p ben --max-objects 100 --no-cleanup 100 seq
hints = 1
sec Cur ops started finished avg MB/s cur MB/s last lat(s) avg lat(s)
0 16 24 8 433.577 -1 0.0726684 0.0405358
1 16 269 253 920.883 980 0.0453323 0.0676502
2 16 435 419 797.339 664 0.043816 0.0790004
3 16 701 685 878.707 1064 0.166523 0.0690671
4 16 710 694 673.494 36 0.302354 0.0718617
5 16 783 767 598.279 292 0.180717 0.104162
6 16 799 783 472.878 64 0.130691 0.105963
Total time run: 6.802636
Total reads made: 800
Read size: 4194304
Object size: 4194304
Bandwidth (MB/sec): 470.406
Average IOPS: 117
Stddev IOPS: 113
Max IOPS: 266
Min IOPS: 9
Average Latency(s): 0.134973
Max latency(s): 1.6875
Min latency(s): 0.0116047