[OpenAFS] Tracing VLDB queries

[Robert Milkowski]

>Once trace points are added tracing can be used to answer all sorts of =
questions. =20

Yes. We've been tracing such information (and others) using DTrace/PID =
provider for years, however having those more abstract probes is going =
to make it easier for everyone,
especially in cases where you are not debugging a bug in AFS itself but =
rather debugging some peculiar client(s) behaviour, etc.


>The specific output from your example is very similar to the
>data that is collected by the baked in audit infrastructure.   The
>following is output from AuriStorFS vlserver:

[...]

>In OpenAFS the audit infrastructure can be enabled per-service and its
>output can be set to files, named pipes, syslog, Linux message queues
>and on AIX its integrated with the OS auditing system.

Yes, for this specific example you are right.
However the new probes allow you to easily answer many other questions, =
like what's the distribution of how long queries take (and then per =
client, per volume, etc.),
 or correlate queries to I/O to disks or network traffic, or CPU, etc.