[RndTbl] Question in last night's meeting about dtrace and user code

[Shawn Wallbridge]

On 15-Mar-06, at 9:21 AM, Stuart Williams wrote:

> Someone asked a question during last night's presentation by Willem
> van Schaik regarding dtrace's ability to instrument user code.  The
> answer as I understood it was that dtrace can't do that, that it can
> only trace OS events.
>
> I vaguely recalled from Bryan Cantrill's presentation and my
> subsequent reading that user code could be instrumented, and it can!
>
> Section 7 of the Usenix paper mentions this
> (http://www.sun.com/bigadmin/content/dtrace/dtrace_usenix.pdf) and
> there's a good slide presentation on Adam Leventhal's blog
> (http://blogs.sun.com/roller/page/ahl/20050301) that briefly explains
> how it's done.
>
> In a limited sense it's not dtrace doing this instrumentation but the
> pid provider.  This provider is written to work with dtrace, and it's
> written using an OS trap (when a probe is enabled), similar to how
> dtrace is implemented on x86.
>
> Stuart Williams.

I think that answer was given in relation to running Linux userland 
applications in a BrandZ zone.

shawn