Message-ID: <524B1E7C.3070108@intel.com>
Date: Tue, 01 Oct 2013 22:11:56 +0300
From: Adrian Hunter <adrian.hunter@intel.com>
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To: Peter Zijlstra <peterz@infradead.org>
CC: Ingo Molnar <mingo@kernel.org>, Frederic Weisbecker <fweisbec@gmail.com>,
        linux-kernel@vger.kernel.org, "Kleen, Andi" <andi.kleen@intel.com>,
        "Shishkin, Alexander" <alexander.shishkin@intel.com>
Subject: PERF_EVENT_IOC_SET_OUTPUT
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Hi

It does not seem possible to use set-output between
task contexts of different types (e.g. a software event
to a hardware event)

If you look at perf_event_set_output():

           /*
            * If its not a per-cpu rb, it must be the same task.
            */
           if (output_event->cpu == -1 && output_event->ctx != event->ctx)
                   goto out;

ctx (perf_event_context) won't be the same for events
of different types.  Is this restriction necessary?

Regards
Adrian
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