io:kernel::done invalid address (0x0) in predicate on FreeBSD 10.1

[Lacey Powers]

Hello Everyone,

I was trying to port a script from Illumos to FreeBSD 10.1, from this 
blog post, here:

http://dtrace.org/blogs/ahl/2014/08/31/openzfs-tuning/

The rw.d script specifically. I wished to use it forsome ZFS tuning and 
testing I have been doing on my workstation.

Here is the script I came up with:

https://gist.github.com/kassandry/219596d7f17e5b128e68

The version I have mostly seems to work, aside from a single error, 
repeated a very large number of times during a run.=(

Example:

dtrace: error on enabled probe ID 3 (ID 58515: io:kernel::done): invalid 
address (0x0) in predicate at DIF offset 60
dtrace: error on enabled probe ID 3 (ID 58515: io:kernel::done): invalid 
address (0x0) in predicate at DIF offset 60

Despite adding

args[0] != NULL

to the predicate for io:::done, it still comes up.

The output seems reasonable, and provides latency and distributions for 
each of the types of bio commands issued during the run.

The only other references I can find to such an issue are here:

https://lists.freebsd.org/pipermail/freebsd-dtrace/2015-February/000346.html

https://github.com/brendangregg/DTrace-tools/blob/master/disk/dilt.d#L80

Which suggests it may be a problem with the io provider? =(

The original script does not have these errors on OmniOS a708424.

I'm not sure what else to do to address the specific errors that are 
coming up with this script.

Have I done something incorrect in porting this particular script to 
FreeBSD 10.1?

Suggestions and advice are most welcome.

If further information is needed, please let me know.

Thank you for your time. =)

Regards,

Lacey