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Subject: Re: [PATCHv11 2.6.36-rc2-tip 5/15]  5: uprobes: Uprobes
 (un)registration and exception handling.
From: Peter Zijlstra <peterz@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
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Date: Mon, 06 Sep 2010 23:18:19 +0200
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On Mon, 2010-09-06 at 17:12 -0400, Christoph Hellwig wrote:
> On Mon, Sep 06, 2010 at 11:06:08PM +0200, Peter Zijlstra wrote:
> > > The other things is that perf currently only supports per-kernel pid
> > > recording, while we'd really need per Posix process, which may contain
> > > multiple threads for useful tracing of complex userspace applications.
> > > I also suspect that this will fit the uprobes model much better given
> > > that the probes will be in any given address space.
> > 
> > perf does report both:
> > 
> >          *      { u32                   pid, tid; } && PERF_SAMPLE_TID
> > 
> > the pid is the process id (thread group leader like) and tid is the
> > task/thread id.
> 
> It records both, but I haven't found a way to only record samples
> or trace things in a Posix Process.
> 
> E.g. perf record -p seems to be only per-thread, not per-process.
> If that has changes recently everything is fine of course.

Hrm, the record code seems to look up all threads for -p and use only a
single thread for -t, didn't actually try it though so it could be
borken.