dtrace discuss - Jan 2008 - Excluding functions/modules from pid provider

Hi All,

Is the approach offered below still the only way to exclude particular
functions or modules when using the pid provider?

Thanks,

.tiller

---



Frome: Morgan.Herrington at Sun.COM Morgan.Herrington at Sun.COM
Subject: [dtrace-discuss] Avoiding few functions using pid provider probes
Date: Tue Aug 23 14:51:31 PDT 2005


Jignesh:

Trying "[!MemoryContextSwitchTo]" won''t work because that
creates a
regular expression character set which does NOT include any of those
listed characters (rather than excluding that particular string).

Unable to come up with an elegant solution, I will offer the following
ugly, brute-force application of regular expressions.

Consider a pattern which excludes functions starting with "M".  Then
add back in those which start with "M" without a following
"e".  Then
add back in those which start with "Me" but without a following
"m".
Continue as necessary for "oryContextSwitchTo". Repeat for
"LockBuffer".

For example:

 pid$target::[!ML]*:entry,  /* exclude funcs starting with "M" or
"L" */
 pid$target::M[!e]*:entry,  /* add back "M" without following
"e"     */
 pid$target::Me[!m]*:entry, /* add back "Me" without following
"m"    */
 pid$target::Mem[!o]*:entry,/* continue this pattern as necessary     */
 pid$target::L[!o]*:entry,  /* repeat for "LockBuffer"               
*/
 pid$target::Lo[!c]*:entry,
 pid$target::Loc[!k]*:entry
 {
    self->ts = timestamp;
 }

When I tried this on a test application, I also specified the "-Z"
switch because several of the patterns did not match any functions.

This entire suggestion is predicated on the assumption that the complexity
of this pattern match is paid during instrumentation time (in order to
avoid run-time costs).  I haven''t actually verified that this is true,
so "buyer beware".

-morgan
>Somewhat helpful
>
>that works only if the wild Character is included .. I am trying to avoid
>MemoryContextSwitchTo
>& LockBuffer
>
>however if I use
>[!MemoryContextSwitchTo]
>it fails
>but if I use
>[!MemoryContextSwitchTo]*
>it works
>
>Also how do I mention both MemoryContextSwitchTo as well as LockBuffer out
>there?

Hi Tiller,

Yes; there''s no generic way of specifically excluding individual
functions
or modules from instrumentation. You could add a predicate, but that will
just keep the function from recording data -- it will stil be instrumented.

Adam

On Tue, Jan 22, 2008 at 10:20:43AM -0800, Tiller Beauchamp
wrote:
> Hi All,
> 
> Is the approach offered below still the only way to exclude particular
> functions or modules when using the pid provider?
> 
> Thanks,
> 
> .tiller
> 
> ---
> 
> 
> 
> Frome: Morgan.Herrington at Sun.COM Morgan.Herrington at Sun.COM
> Subject: [dtrace-discuss] Avoiding few functions using pid provider probes
> Date: Tue Aug 23 14:51:31 PDT 2005
> 
> 
> Jignesh:
> 
> Trying "[!MemoryContextSwitchTo]" won''t work because
that creates a
> regular expression character set which does NOT include any of those
> listed characters (rather than excluding that particular string).
> 
> Unable to come up with an elegant solution, I will offer the following
> ugly, brute-force application of regular expressions.
> 
> Consider a pattern which excludes functions starting with "M". 
Then
> add back in those which start with "M" without a following
"e".  Then
> add back in those which start with "Me" but without a following
"m".
> Continue as necessary for "oryContextSwitchTo". Repeat for
"LockBuffer".
> 
> For example:
> 
>  pid$target::[!ML]*:entry,  /* exclude funcs starting with "M" or
"L" */
>  pid$target::M[!e]*:entry,  /* add back "M" without following
"e"     */
>  pid$target::Me[!m]*:entry, /* add back "Me" without following
"m"    */
>  pid$target::Mem[!o]*:entry,/* continue this pattern as necessary     */
>  pid$target::L[!o]*:entry,  /* repeat for "LockBuffer"           
*/
>  pid$target::Lo[!c]*:entry,
>  pid$target::Loc[!k]*:entry
>  {
>     self->ts = timestamp;
>  }
> 
> When I tried this on a test application, I also specified the
"-Z"
> switch because several of the patterns did not match any functions.
> 
> This entire suggestion is predicated on the assumption that the complexity
> of this pattern match is paid during instrumentation time (in order to
> avoid run-time costs).  I haven''t actually verified that this is
true,
> so "buyer beware".
> 
> -morgan
> 
> >Somewhat helpful
> >
> >that works only if the wild Character is included .. I am trying to
avoid
> >MemoryContextSwitchTo
> >& LockBuffer
> >
> >however if I use
> >[!MemoryContextSwitchTo]
> >it fails
> >but if I use
> >[!MemoryContextSwitchTo]*
> >it works
> >
> >Also how do I mention both MemoryContextSwitchTo as well as LockBuffer
out
> >there?
> 
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org
-- 
Adam Leventhal, Fishworks                        http://blogs.sun.com/ahl