Rahul,
On Fri, May 19, 2006 at 04:09:41PM -0600, Rahul Saxena wrote:
>
> I am trying to use perfrmon and libpfm with the Pin Instrumentation system.
> http://rogue.colorado.edu/Pin/index.html
> Pin is a dynamic Binary Instrumentation framework which allows users
> to write custom instrumentation and analysis routines for a binary.
>
> I am using Pin to setup a perfrmon context and a signal handler to
> handle SIGIO signals on PMU buffer overflows. Pin can setup these
> things in the same address space as the binary.
>
> I am using the SIGIO mechanism because it appears to the most
> lightweight way of gathering PMU data when the process is running. The
> reason for using Pin with perfmon is also to monitor a binary without
> recompiling it.
>
I know about Pin but it seems overkill to use it in this context.
Perfmon can monitor unmodified binaries. In fact that's one of the top
goals. I would not use Pin just because it allows you to get control
to setup monitor. You can as well monitor a process from another one,
including for sampling. The cost is not much more. The sampling buffer
is filled up in the context of the monitored process. When the buffer
is full a message (or signal) is sent to the controlling process which
has the sampling buffer remapped.
You can also attach to a running process. You do this by leveraging the
ptrace() interface. That is what Pin probably does too. You use ptrace
to stop (attach to) the process, attach the perfmon context, and then you
resume (detach from) the process.
I have provided example of how to do this in the libpfm example subdir.
You can grab the latest version at:
http://perfmon2.sf.net
Hope this helps.
> The problem I am facing is that although the PMU send buffer overflow
> signals during the period that Pin is setting up the binary to
> execute. It stops working before the code from the target binary
> executes.
>
> I have experimented to check if it is a problem with the signal
> handling, but that doesnt seem to be the case because signals are
> still caught while the target binary is running. Its just that the PMU
> information stops.
>
> I have tried counting simple things such as the number of retired
> instructions from the PMU but that too stops showing up. ( But binary
> continues to execute. )
>
> I am not sure if the problem lies with Pin or in the way Pin interacts
> with perfmon functionality and the creation of the PMU context. Pin
> works by execing the target binary ( the one being monitored ) and
> then ptracing to take control of its execution. It then injects itself
> in the binary's address space and then interacts with the binary in
> its own address space. It can at a later point allow the binary to
> execute, independent of itself.
>
> Sorry to write a long mail, which is mostly not about perfmon, but any
> clues or questions which can help me figure out what I can do get
> perfmon to work along with Pin will be greatly appreciated.
>
> Thanks,
> rahul
>
> --
> The World's Greatest Dream Machine
>
> _______________________________________________
> perfmon mailing list
> [email protected]
> http://www.hpl.hp.com/hosted/linux/mail-archives/perfmon/
--
-Stephane
_______________________________________________
perfmon mailing list
[email protected]
http://www.hpl.hp.com/hosted/linux/mail-archives/perfmon/
