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Subject: Re: [PATCH 1/2] perf: Add persistent events
From: Peter Zijlstra <peterz@infradead.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@elte.hu>, Frederic Weisbecker <fweisbec@gmail.com>,
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Date: Sun, 23 May 2010 20:40:47 +0200
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On Sun, 2010-05-23 at 20:33 +0200, Borislav Petkov wrote:
> From: Peter Zijlstra <peterz@infradead.org>
> Date: Sun, May 23, 2010 at 08:15:13PM +0200
> 
> > On Sat, 2010-05-22 at 21:00 +0200, Borislav Petkov wrote:
> > > Register and enable events marked as persistent right after perf events
> > > has initialized.
> > > 
> > > Not-yet-signed-off-by: Borislav Petkov <bp@alien8.de>
> > 
> > Nah, this is totally wrong.
> > 
> > A persistent event would simply be a regular event, but created by the
> > kernel and not tied to a file-desc's lifetime.
> 
> So you're saying the trace_mce_record() tracepoint for example should
> be created completely internally in the kernel and cease to be a
> tracepoint? Will it still be able to be selected by perf -e?

No, it should be a regular tracepoint as far as tracepoints are
concerned.

But the only thing persistence should add is an instance of a
perf_event, it should not modify either the perf_event nor the
tracepoint code.