oops .. typo
Corey J Ashford/Beaverton/i...@ibmus wrote on 07/22/2009 11:29:22 AM:
> I know for a fact that it's possible to ptrace attach to threads
(tasks).
> We have a tool which relies on that + perfmon2 for per-thread
performance
> monitoring.
>
> If you are really curious, you could start digging into the kernel code
to
> figure out where that "operation not permitted" error is coming from,
and
> perhaps that could lead to a clue as to what is going on.
>
> On the other hand, Stephane the 2.6.30 perfmon2 won't require ptrace, so
^ said
> if you can wait, that would be a better solution.
>
> - Corey
>
> Tanima Dey <[email protected]> wrote on 07/22/2009 07:57:32 AM:
>
> > Hi,
> > Yes the line 136 prints the application thread id correctly. I also
> > don't know what could be the problem. May be ptrace does not allow
> > threadID as parameter. When will the version 2.6.30 be available?
> >
> > Thanks
> > Tanima.
> >
> > From: Corey J Ashford <[email protected]>
> > To: Tanima Dey <[email protected]>
> > Cc: Corey Ashford <[email protected]>; Perfmon <perfmon2-
> > [email protected]>
> > Sent: Tuesday, July 21, 2009 12:12:15 AM
> > Subject: Re: [perfmon2] About per-thread monitoring
>
> > Hi Tanima,
> >
> > Does the " fprintf(stdout, "apptid %d gettid(): %d \n",apptid,
> > gettid());" at line 136 print correct looking task ids? If the
> > apptid is zero, maybe you need to add a "volatile" keyword added to
> > the declaration of apptid, since it is written in one thread, and
> > accessed in another.
> >
> > If the apptid is ok looking, and you're getting operation not
> > permitted, that's seems very odd. Ptrace ought to be able to attach
> > to threads you have created.
> >
> > Otherwise, the code looks ok to me. Maybe Stephane has some ideas.
> >
> > Regards,
> >
> > - Corey
> >
> > Corey Ashford
> > Software Engineer
> > IBM Linux Technology Center, Linux Toolchain
> > Beaverton, OR
> > 503-578-3507
> > [email protected]
> >
> >
> > Tanima Dey <[email protected]> wrote on 07/20/2009 12:37:55 PM:
> >
> > > Tanima Dey <[email protected]>
> > > 07/20/2009 12:37 PM
> > >
> > > To
> > >
> > > Corey J Ashford/Beaverton/i...@ibmus
> > >
> > > cc
> > >
> > > Corey Ashford <[email protected]>, Perfmon <perfmon2-
> > > [email protected]>
> > >
> > > Subject
> > >
> > > Re: [perfmon2] About per-thread monitoring
> > >
> > > Hi,
> > > I am attaching the code.
> > > Thank you very much.
> > > Tanima.
> > >
> > > From: Corey J Ashford <[email protected]>
> > > To: Tanima Dey <[email protected]>
> > > Cc: Corey Ashford <[email protected]>; Perfmon <perfmon2-
> > > [email protected]>
> > > Sent: Saturday, July 18, 2009 10:26:11 PM
> > > Subject: Re: [perfmon2] About per-thread monitoring
> >
> > > Can you post the code where you are doing the fork/exec of the app,
> > > and following ptrace call? Maybe we can spot the problem easier that
> > > way, because I'm a little confused about the terminology
> > > "appThread". If appThread is a pthread id, that would be the reason
> > > that ptrace is not working... it takes task ids, rather than pthread
> ids.
> > >
> > > - Corey
> > >
> > > Tanima Dey <[email protected]> wrote on 07/18/2009 03:55:02 PM:
> > >
> > > > Tanima Dey <[email protected]>
> > > > 07/18/2009 03:55 PM
> > > >
> > > > To
> > > >
> > > > Corey Ashford <[email protected]>
> > > >
> > > > cc
> > > >
> > > > Perfmon <[email protected]>
> > > >
> > > > Subject
> > > >
> > > > Re: [perfmon2] About per-thread monitoring
> > > >
> > > > Hi,
> > > > Yes, I have studied that example, and wrote similar code, but for
> > > > the appThread. But it shows me the same error message for ptrace()
> > > > while attaching the task. I have given the appThread ID instead of
> > > > the process ID, and it shows the message:
> > > >
> > > > "cannot attach to threadID, operation is not permitted"
> > > >
> > > > Can you help?
> > > > Thanks
> > > > Tanima.
> > > >
> > > > From: Corey Ashford <[email protected]>
> > > > To: Tanima Dey <[email protected]>
> > > > Cc: Perfmon <[email protected]>
> > > > Sent: Friday, July 17, 2009 6:20:09 PM
> > > > Subject: Re: [perfmon2] About per-thread monitoring
> > > >
> > > > On 07/16/2009 04:33 PM, Tanima Dey wrote:
> > > > >
> > > > > Hi,
> > > > >
> > > > > Thanks for the reply.
> > > > >
> > > > > It is mentioned in the manual that the thread to which the
context
> is
> > > > > attached is the monitored thread, in my case then it is the
> application
> > > > > thread to which the context should be loaded, right? If it is
so,
> I am
> > > > > initializing and loading the context in the appThread, and
trying
> to
> > > > > read the counters value in the monitor thread. So I have used
> ptrace()
> > > > > to stop the appThread in the monitor thread and trying to read
the
> > > > > counters, but it is showing the error message: Cannot attach:
> Operation
> > > > > not permitted. Also I tried to read by saving the file
descriptor
> > > > > variable, it is also not working.
> > > > >
> > > > > Must the per-thread monitoring always be self-monitoring?
> Otherwise, I
> > > > > think it will always be the case that the monitoring thread wont
> have
> > > > > any access to PMU state initialized by the appThread.
> > > > >
> > > > > What wrong I am doing here?Do you have any examples for
perthread
> > > > > monitoring using threads?
> > > > >
> > > >
> > > > You can monitor from the same thread or from another thread, or
from
>
> > > > another thread in a different process.
> > > >
> > > > Have you looked at libpfm/examples_v2.x/task_attach.c ?
> > > >
> > > > It is an example of monitoring events in another task (i.e.
process
> or
> > > > thread).
> > > >
> > > > - Corey
> > > >
> > >
> >
>
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> > > [attachment "pstart7_8.c" deleted by Corey J Ashford/Beaverton/IBM]
>
>
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