blkparse not displaying all events when tracing >1 devices?

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Hello,

If I trace *2* block devices (I only tried 1 or 2, not > 2) using a single blktrace command, then blkparse the resulting output file set, I get an abridged display of events to only one of the devices.

If I instead launch two separate blktrace commands, each to a single block device and unique output file, then blkparse the resulting output files independently, I appear to get all the events on each device.

FWIW, the two block devices are actually two paths to the same HDD but I doubt that is relevant to this problem.

I'm pasting in my notes below. This was done using a build from a clone of the blktrace git repo taken this afternoon.

spu0103# blktrace -V
blktrace version 2.0.0

First tried the multi-device syntax shown in the PDF users guide:

spu0103# blktrace /dev/sdbk /dev/sdam -o 5 &

This program initiates SCSI commands to both devices and reads to one of them:

spu0103# nzgeninventory > nzgi.5 2>&1
spu0103# killall blktrace

Evidently blktrace captured everything:

spu0103# === sdbk ===
  CPU  0:                    0 events,        0 KiB data
  CPU  1:                    4 events,        1 KiB data
  CPU  2:                    5 events,        1 KiB data
  CPU  3:                    5 events,        1 KiB data
  CPU  4:                    5 events,        1 KiB data
  CPU  5:                    0 events,        0 KiB data
  CPU  6:                    1 events,        1 KiB data
  CPU  7:                    1 events,        1 KiB data
  Total:                    21 events (dropped 0),        2 KiB data
=== sdam ===
  CPU  0:                    9 events,        1 KiB data
  CPU  1:                    7 events,        1 KiB data
  CPU  2:                    6 events,        1 KiB data
  CPU  3:                    6 events,        1 KiB data
  CPU  4:                    6 events,        1 KiB data
  CPU  5:                   10 events,        1 KiB data
  CPU  6:                    6 events,        1 KiB data
  CPU  7:                   11 events,        1 KiB data
  Total:                    61 events (dropped 0),        4 KiB data

[1]+  Done                       blktrace /dev/sdbk /dev/sdam -o 5

But blkparse shows me only some events from one of the devices:

spu0103# blkparse -q -i 5
Input file 5.blktrace.1 added
Input file 5.blktrace.2 added
Input file 5.blktrace.3 added
Input file 5.blktrace.4 added
Input file 5.blktrace.6 added
Input file 5.blktrace.7 added
 66,96   1        1     0.000000000  3786  G   N [nzgeninventory.]
 66,96   1        2     0.000002043  3786  P   N [nzgeninventory.]
 66,96   3        1     0.000496874     0  C   R (12 00 00 00 24 00 ..) [0]
 66,96   3        2     0.000597626  3786  G   N [nzgeninventory.]
 66,96   3        3     0.000599460  3786  P   N [nzgeninventory.]
 66,96   2        1     0.001022051     0  C   R (12 00 00 00 a4 00 ..) [0]
 66,96   2        2     0.001094954  3786  G   N [nzgeninventory.]
 66,96   2        3     0.001096781  3786  P   N [nzgeninventory.]
 66,96   4        1     0.001705551     0  C   R (12 01 83 00 fc 00 ..) [0]
 66,96   4        2     0.002156748  3786  G   N [nzgeninventory.]
 66,96   4        3     0.002158788  3786  P   N [nzgeninventory.]


Let's try two separate instances of blktrace?

spu0103# blktrace /dev/sdbk -o 6a &
spu0103# blktrace /dev/sdam -o 6b &
spu0103# nzgeninventory > nzgi.6 2>&1
spu0103# killall blktrace

Same # of events captured:

spu0103# === sdbk ===
  CPU  0:                    1 events,        1 KiB data
  CPU  1:                    0 events,        0 KiB data
  CPU  2:                    1 events,        1 KiB data
  CPU  3:                    0 events,        0 KiB data
  CPU  4:                    4 events,        1 KiB data
  CPU  5:                    5 events,        1 KiB data
  CPU  6:                    5 events,        1 KiB data
  CPU  7:                    5 events,        1 KiB data
  Total:                    21 events (dropped 0),        2 KiB data
=== sdam ===
  CPU  0:                   10 events,        1 KiB data
  CPU  1:                    9 events,        1 KiB data
  CPU  2:                    7 events,        1 KiB data
  CPU  3:                    9 events,        1 KiB data
  CPU  4:                    6 events,        1 KiB data
  CPU  5:                    6 events,        1 KiB data
  CPU  6:                    6 events,        1 KiB data
  CPU  7:                    8 events,        1 KiB data
  Total:                    61 events (dropped 0),        4 KiB data

[2]+  Done                       blktrace /dev/sdam -o 6b
[1]+  Done                       blktrace /dev/sdbk -o 6a

But this time the blkparse output is what I expect:

spu0103# blkparse -q -i 6a
Input file 6a.blktrace.0 added
Input file 6a.blktrace.2 added
Input file 6a.blktrace.4 added
Input file 6a.blktrace.5 added
Input file 6a.blktrace.6 added
Input file 6a.blktrace.7 added
 67,224  4        1     0.000000000  4247  G   N [(null)]
 67,224  4        2     0.000002179  4247  P   N [(null)]
 67,224  4        3     0.000002361  4247  I   R 36 (12 00 00 00 24 00 ..) [(null)]
 67,224  4        4     0.000003055  4247  D   R 36 (12 00 00 00 24 00 ..) [(null)]
 67,224  6        1     0.000498033     0  C   R (12 00 00 00 24 00 ..) [0]
 67,224  6        2     0.000583480  4247  G   N [(null)]
 67,224  6        3     0.000585724  4247  P   N [(null)]
 67,224  6        4     0.000585880  4247  I   R 164 (12 00 00 00 a4 00 ..) [(null)]
 67,224  6        5     0.000586369  4247  D   R 164 (12 00 00 00 a4 00 ..) [(null)]
 67,224  5        1     0.000996791     0  C   R (12 00 00 00 a4 00 ..) [0]
 67,224  5        2     0.001057014  4247  G   N [(null)]
 67,224  5        3     0.001059622  4247  P   N [(null)]
 67,224  5        4     0.001059775  4247  I   R 252 (12 01 83 00 fc 00 ..) [(null)]
 67,224  5        5     0.001065073  4247  D   R 252 (12 01 83 00 fc 00 ..) [(null)]
 67,224  7        1     0.001683205     0  C   R (12 01 83 00 fc 00 ..) [0]
 67,224  7        2     0.001989782  4247  G   N [(null)]
 67,224  7        3     0.001991606  4247  P   N [(null)]
 67,224  7        4     0.001991753  4247  I   R 252 (12 01 80 00 fc 00 ..) [(null)]
 67,224  7        5     0.001992269  4247  D   R 252 (12 01 80 00 fc 00 ..) [(null)]
 67,224  0        1     0.002599310     0  C   R (12 01 80 00 fc 00 ..) [0]

spu0103# blkparse -q -i 6b
Input file 6b.blktrace.0 added
Input file 6b.blktrace.1 added
Input file 6b.blktrace.2 added
Input file 6b.blktrace.3 added
Input file 6b.blktrace.4 added
Input file 6b.blktrace.5 added
Input file 6b.blktrace.6 added
Input file 6b.blktrace.7 added
 66,96   2        1     0.000000000  4247  G   N [nzgeninventory.]
 66,96   2        2     0.000002148  4247  P   N [nzgeninventory.]
 66,96   2        3     0.000002316  4247  I   R 36 (12 00 00 00 24 00 ..) [nzgeninventory.]
 66,96   2        4     0.000002955  4247  D   R 36 (12 00 00 00 24 00 ..) [nzgeninventory.]
 66,96   4        1     0.000419015     0  C   R (12 00 00 00 24 00 ..) [0]
 66,96   4        2     0.000490802  4247  G   N [nzgeninventory.]
 66,96   4        3     0.000493304  4247  P   N [nzgeninventory.]
 66,96   4        4     0.000493454  4247  I   R 164 (12 00 00 00 a4 00 ..) [nzgeninventory.]
 66,96   4        5     0.000493973  4247  D   R 164 (12 00 00 00 a4 00 ..) [nzgeninventory.]
 66,96   6        1     0.000909171     0  C   R (12 00 00 00 a4 00 ..) [0]
 66,96   6        2     0.000967297  4247  G   N [nzgeninventory.]
 66,96   6        3     0.000969818  4247  P   N [nzgeninventory.]
 66,96   6        4     0.000970016  4247  I   R 252 (12 01 83 00 fc 00 ..) [nzgeninventory.]
 66,96   6        5     0.000970634  4247  D   R 252 (12 01 83 00 fc 00 ..) [nzgeninventory.]
 66,96   5        1     0.001573121     0  C   R (12 01 83 00 fc 00 ..) [0]
 66,96   5        2     0.001883295  4247  G   N [nzgeninventory.]
 66,96   5        3     0.001885647  4247  P   N [nzgeninventory.]
 66,96   5        4     0.001885878  4247  I   R 252 (12 01 80 00 fc 00 ..) [nzgeninventory.]
 66,96   5        5     0.001886469  4247  D   R 252 (12 01 80 00 fc 00 ..) [nzgeninventory.]
 66,96   7        1     0.002486674     0  C   R (12 01 80 00 fc 00 ..) [0]
 66,96   7        2     0.002682738  4247  G   N [nzgeninventory.]
 66,96   7        3     0.002684715  4247  P   N [nzgeninventory.]
 66,96   7        4     0.002684877  4247  I   R 252 (25 00 ..) [nzgeninventory.]
 66,96   7        5     0.002685351  4247  D   R 252 (25 00 ..) [nzgeninventory.]
 66,96   0        1     0.003222215     0  C   R (25 00 ..) [0]
 66,96   0        2     0.003387279  4247  A   R 2112 + 1 <- (66,97) 2049
 66,96   0        3     0.003387516  4247  Q   R 2112 + 1 [nzgeninventory.]
 66,96   0        4     0.003388578  4247  G   R 2112 + 1 [nzgeninventory.]
 66,96   0        5     0.003389361  4247  P   N [nzgeninventory.]
 66,96   0        6     0.003389889  4247  I   R 2112 + 1 [nzgeninventory.]
 66,96   0        7     0.003390646  4247  U   N [nzgeninventory.] 1
 66,96   0        8     0.003391420  4247  D   R 2112 + 1 [nzgeninventory.]
 66,96   1        1     0.003547936     0  C   R 2112 + 1 [0]
 66,96   1        2     0.003743980  4247  A   R 1197744189 + 1 <- (66,99) 2049
 66,96   1        3     0.003744226  4247  Q   R 1197744189 + 1 [nzgeninventory.]
 66,96   1        4     0.003745333  4247  G   R 1197744189 + 1 [nzgeninventory.]
 66,96   1        5     0.003746269  4247  P   N [nzgeninventory.]
 66,96   1        6     0.003746782  4247  I   R 1197744189 + 1 [nzgeninventory.]
 66,96   1        7     0.003747532  4247  U   N [nzgeninventory.] 1
 66,96   1        8     0.003748303  4247  D   R 1197744189 + 1 [nzgeninventory.]
 66,96   3        1     0.003903074     0  C   R 1197744189 + 1 [0]
 66,96   3        2     0.004043041  4247  A   R 1944782754 + 1 <- (66,100) 2049
 66,96   3        3     0.004043263  4247  Q   R 1944782754 + 1 [nzgeninventory.]
 66,96   3        4     0.004044337  4247  G   R 1944782754 + 1 [nzgeninventory.]
 66,96   3        5     0.004045072  4247  P   N [nzgeninventory.]
 66,96   3        6     0.004045558  4247  I   R 1944782754 + 1 [nzgeninventory.]
 66,96   3        7     0.004046260  4247  U   N [nzgeninventory.] 1
 66,96   3        8     0.004047013  4247  D   R 1944782754 + 1 [nzgeninventory.]
 66,96   2        5     0.004201336     0  C   R 1944782754 + 1 [0]


I tried the '-m' (show missing events) option shown in the PDF for blkparse, but it doesn't appear to be a valid option. I don't think that it was intended for this purpose anyway...
spu0103# blkparse -q -m -i 7
blkparse: invalid option -- 'm'

I also tried an alternate form of launching blktrace, this had no impact:
spu0103# blktrace -d /dev/sdbk -d /dev/sdam -o 7 &

I assume the problem lies in blkparse.  At least I have a workaround.

Thanks,
Brett
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