On 02/16/10 02:31 PM, Nicolas Williams wrote:
On Tue, Feb 16, 2010 at 02:12:35PM +0100, Mark Phalan wrote:
I'm working on adding USDT probes to a library. The library is built in
ON and hence includes CTF data. I've set up a number of translators for
the probes to use to avoid exposing the internals of the library.
Unfortunately it appears as though dtrace can't take advantage of the
CTF data in userspace libraries to walk library data structures. The
library data-structures are complex and cannot simply be included in the
provider support file so I have to resort to teaching the library to
setup the arguments for dtrace to consume with an intermediate data
structure. This data strucutre can be then included in the provider
support file (in /usr/lib/dtrace).
I couldn't find a CR/RFE tracking this. Is there one?
What you're looking for is called "is-enabled" probes. These are probes
that do have disabled probe effects (a branch, basically). You get to
gather the data needed for the probes only when the probes are enabled.
Yup, I'm planning on using the is-enabled probes to reduce the run-time
cost of building the arguments when the probes aren't enabled.
User-land pointer chasing and structured type handling via simple syntax
that relies CTF is not a feature of DTrace right now; you can only do
that in kernel-land.
Thats what I feared :( I couldn't find the CR tracking that though.
Perhaps I should just open one.
Thanks,
-M
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