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Re: 2 problems with sprof


On Sun, Sep 23, 2001 at 12:21:24AM -0700, Ulrich Drepper wrote:
> "H . J . Lu" <hjl@lucon.org> writes:
> 
> > I'd like to profile more than one DSO with LD_PROFILE at a time. The
> > current code doesn't support it. I assume it will take some effort to
> > make it to work. Is anyone else interested in it? It will be nice to
> > have someone to work with on it.
> 
> This is the same problem as profiling dynamically linked applications.
> Almost the same.  You have multiple not consecutive code segments and
> the simple (and fast) bucket hashing won't work anymore.  So,

Did you mean the number of text segments in the program header is
different between DSO and executable? I don't think it is the case.

> implement profiling of dynamically linked applications first.  Ideally
> this happens using some functions which then could be used in ld.so as
> well.  And yes, this will require a lot of effort.

I don't think they are the same problem. Right now, we have the data
structure to profile only one file at a time. I'd like to do multiple
DSOs first. I will keep profiling executable in mind when I make the
change. May I suggest we do

LD_PROFILE=dso1:dso2...		# profile a list of DSOs
LD_PROFILE_EXEC=		# profile executable
LD_PROFILE_ALL=			# profile all, including executable

> 
> [I personally don't feel the urge to do this right now since we still
> have no high-resolution timers.  Without them any new profiling code
> is rather meaningless.]

Can we change HZ in kernel to get high-resolution timer?


H.J.


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