dtrace discuss - Nov 2008 - Runtime customization of a dscript & pre-processing

I would like to make some execution time decisions as to which
libraries to trace and which ones not to.

For ex:
1. I use hotuser script and identify a bunch of functions/libraries
taking the most time under load.
2. Now I would like to apply hotuser kind of profiling only to those
libraries and heavier load(which might not be possible otherwise).

In such cases, I probably need to have parameterised predicate list or
dynamically generated dscripts.
One thought that occurs to me is to have some kind of pre-processing
option available in dtrace. Write a wrapper shell/perl script that
helps identify decision points for the pre-processor and conditionally
execute different instructions.
Probably pre-processing is already present. I wasn''t able to find it
in some of the documentation I looked at on the net.

Can someone suggest me a solution for the scenario I mention. Also is
pre-processing option available in dtrace.

-Shiv

On Wed, Nov 12, 2008 at 08:42:00AM +0530, S h i v wrote:
> I would like to make some execution time decisions as to which
> libraries to trace and which ones not to.
> 
> For ex:
> 1. I use hotuser script and identify a bunch of functions/libraries
> taking the most time under load.
> 2. Now I would like to apply hotuser kind of profiling only to those
> libraries and heavier load(which might not be possible otherwise).
> 
> In such cases, I probably need to have parameterised predicate list or
> dynamically generated dscripts.
> One thought that occurs to me is to have some kind of pre-processing
> option available in dtrace. Write a wrapper shell/perl script that
> helps identify decision points for the pre-processor and conditionally
> execute different instructions.
> Probably pre-processing is already present. I wasn''t able to find
it
> in some of the documentation I looked at on the net.
If you add ''-C'' to the dtrace arguments, it will run the C
preprocessor.
You can then use -DVAR=value to pass in whatever you need.

Cheers,
- jonathan

On Wed, Nov 12, 2008 at 11:32 PM, Jonathan Adams <jonathan.adams at
sun.com> wrote:
> On Wed, Nov 12, 2008 at 08:42:00AM +0530, S h i v wrote:
<snip>
>> One thought that occurs to me is to have some kind of pre-processing
>> option available in dtrace.
<snip>
>
> If you add ''-C'' to the dtrace arguments, it will run the
C preprocessor.
> You can then use -DVAR=value to pass in whatever you need.
>
Just what I was looking for ! Thanks.

-Shiv