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Subject: Re: [PATCH 3/5] perf: Ability to enable in a paused mode
From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Paul Mackerras <paulus@samba.org>,
       Stephane Eranian <eranian@google.com>,
       Cyrill Gorcunov <gorcunov@gmail.com>,
       Zhang Yanmin <yanmin_zhang@linux.intel.com>,
       Steven Rostedt <rostedt@goodmis.org>
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Date: Sat, 12 Jun 2010 11:44:26 +0200
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On Sat, 2010-06-12 at 09:34 +0200, Frederic Weisbecker wrote:
>  struct pmu {
>         int (*enable)                   (struct perf_event *event);
> +       /*
> +        * Reserve acts like enable, except the event must go in a "pause"
> +        * state. Ie: it is scheduled but waiting to be started
> +        * with the ->start() callback.
> +        */
> +       int (*reserve)                  (struct perf_event *event);
>         void (*disable)                 (struct perf_event *event); 

Urgh, so then we have, enable(), reserve() and start(), that's just too
much. Also, you need to visit all pmu implementations if you touch
struct pmu like that.