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Subject: Re: [PATCH 1/4] tracing: Use the perf recursion protection from
 trace event
From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Paul Mackerras <paulus@samba.org>, Steven Rostedt <rostedt@goodmis.org>,
       Masami Hiramatsu <mhiramat@redhat.com>, Jason Baron <jbaron@redhat.com>
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Date: Sun, 22 Nov 2009 17:50:45 +0100
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On Sun, 2009-11-22 at 17:37 +0100, Frederic Weisbecker wrote:

> That's cleaner but adds an unnecessary overhead in the trace event
> path. We already disable the interrupts there. That's why I preferred
> to let the caller decide.

The trace path is already far from optimal, so I'd rather penalize that
than the regular swcounter path.