Re: [PATCH v3] Tracepoint Tapset for Memory Subsystem

[Rajasekhar Duddu <rajduddu@linux.vnet.ibm.com>]

On Wed, Oct 07, 2009 at 03:51:07PM -0400, Frank Ch. Eigler wrote:
> Rajasekhar Duddu <rajduddu@linux.vnet.ibm.com> writes:
> 
> > [...]
> >> Nice.  I thought that the raison d'etre for these aliases was to
> >> abstract the presence or absence of tracepoints, so is there no
> >> fallback kprobe available?  Something like this:
> >> 
> > Fallback kprobe is not available for other memory functions because
> > the variables exported by them are will be modified.
> 
> Could you elaborate?  Do you mean that the same values may not be
> available from a kprobe context?
> 
>
Hi Frank,
	 Yes, the same values may not be available from a kprobe
context, for example if we take "ret" variable as it is populated mid-way in
the  function and it is also the return value of a function which can
be captured only by a return probe. But by a return probe we cannot
capture the formal parameters of the memory function.
 

Thanks
-- 
Rajasekhar Duddu (rajduddu@linux.vnet.ibm.com),
Linux on System z - CSVT, IBM LTC, Bangalore.