| Date | Mon, 14 Jul 2014 12:39:26 +0000 (UTC) | From | Mathieu Desnoyers <> | Subject | Re: [patch 54/55] timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONIC[_RAW] |
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----- Original Message ----- > From: "Peter Zijlstra" <peterz@infradead.org> > To: "Thomas Gleixner" <tglx@linutronix.de> > Cc: "LKML" <linux-kernel@vger.kernel.org>, "John Stultz" <john.stultz@linaro.org>, "Steven Rostedt" > <rostedt@goodmis.org>, "Mathieu Desnoyers" <mathieu.desnoyers@efficios.com> > Sent: Monday, July 14, 2014 5:47:50 AM > Subject: Re: [patch 54/55] timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONIC[_RAW] > > On Fri, Jul 11, 2014 at 01:45:19PM -0000, Thomas Gleixner wrote: > > +static struct tk_fast tk_fast_raw ____cacheline_aligned; > > +static struct tk_fast tk_fast_mono ____cacheline_aligned; > > Question to the 'trace maniacs'; why do you lot need access to mono_raw? > > I would much prefer to limit choice here.
For LTTng, which I guess qualifies as bring part of the aforementioned trace maniacs group, we only need the "tk_fast_mono" clock. We don't need mono_raw.
We can then correlate with user-space traces by using tk_fast_mono in kernel-space and using CLOCK_MONOTONIC in userspace.
Thanks,
Mathieu
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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