pt-diskstats reports wrong amount of writes/second

[Daniel Nichter]

Imported from http://code.google.com/p/aspersa/issues/detail?id=137:

The problem I have is that I get different results when looking at iostat and diskstats (5 second intervals):

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util
sdc 0.00 277.56 104.01 415.83 936.27 5574.35 468.14 2787.17 12.52 6.34 12.18 1.24 64.57

#ts device rd_s rd_avkb rd_mb_s rd_mrg rd_cnc rd_rt wr_s wr_avkb wr_mb_s wr_mrg wr_cnc wr_rt busy in_prg
 {1} sdc1 133.2 10.1 0.7 0% 0.9 6.6 841.5 13.9 5.7 42% 12.3 14.7 87% 0
 {1} sdc1 154.8 7.9 0.6 0% 0.7 4.3 590.4 9.1 2.6 12% 9.1 15.4 71% 0

The amount of writes/s that iostat is measuring is about 5600 while diskstats only mentions 600.
/proc/diskstats tells me iostat is correct

raw diskstats output:
TS 1301045501.005860000 2011-03-25 05:31:41
  8 33 sdc1 1572537676 2369344 3687151364 1575056414 2541895139 1708184481 3991989096 121136333 1 982122453 1798311795
TS 1301045506.010994000 2011-03-25 05:31:46
  8 33 sdc1 1572538262 2369344 3687156316 1575060551 2541899787 1708186654 3992043720 121207970 4 982126782 1798388127
TS 1301045511.016149000 2011-03-25 05:31:51
  8 33 sdc1 1572538898 2369344 3687161404 1575064096 2541903848 1708186950 3992078608 121272417 1 982130754 1798455962
TS 1301045516.021280000 2011-03-25 05:31:56

[Brian Fraser (fraserbn)]

Marking this as "Won't fix" as I can't seem able to reproduce it, and the tool itself was rewritten from scratch. Daniel, if you can reproduce it again, please let me know and/or reopen this?

[Daniel Nichter (daniel-nichter)]

Changing to Invalid since it's not that we're not going to fix it, but rather "it" (the bug) has been invalidated by the fact that you rewrote the tool.

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PT-418