linux-kernel - Re: [PATCH v0 04/71] itrace: Infrastructure for instruction flow tracing units

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Date:	Thu, 19 Dec 2013 16:54:27 +0200
From:	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>, Mike Galbraith <efault@....de>,
	Namhyung Kim <namhyung@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Stephane Eranian <eranian@...gle.com>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH v0 04/71] itrace: Infrastructure for instruction flow tracing units

Peter Zijlstra <peterz@...radead.org> writes:

> On Thu, Dec 19, 2013 at 12:57:59PM +0100, Peter Zijlstra wrote:
> So you're basically forced to stop the tracing on PMI anyhow; so your
> continuous tracing argument goes out the window.

It's only stopped inside the PMI handler to set up another buffer, and
is then started again, so no useful trace is lost. PMI handler is not
traced. What you're proposing is stopping it for good till perf collects
the previous data, which will lose us a lot of trace. So my argument
stands.

Regards,
--
Alex
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