Message-ID: <1352935816.18025.75.camel@gandalf.local.home>
Subject: Re: [RFC] perf: need to expose sched_clock to correlate user
 samples with kernel samples
From: Steven Rostedt <rostedt@goodmis.org>
To: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Stephane Eranian <eranian@google.com>,
        LKML <linux-kernel@vger.kernel.org>, "mingo@elte.hu" <mingo@elte.hu>,
        Paul Mackerras <paulus@samba.org>, Anton Blanchard <anton@samba.org>,
        Will Deacon <will.deacon@arm.com>,
        "ak@linux.intel.com" <ak@linux.intel.com>,
        Pekka Enberg <penberg@gmail.com>,
        Robert Richter <robert.richter@amd.com>, tglx <tglx@linutronix.de>
Date: Wed, 14 Nov 2012 18:30:16 -0500
In-Reply-To: <50A41A85.9090800@linaro.org>
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	 <1350408232.2336.42.camel@laptop> <509DB632.7070305@linaro.org>
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On Wed, 2012-11-14 at 14:26 -0800, John Stultz wrote:

> > There's also trace_clock_counter() which isn't even a clock :-)  It's
> > just a incremental atomic counter that goes up every time it's called.
> > This is the most synced clock, but is absolutely meaningless for
> > timestamps. It's just a way to show ordered events.
> 
> Oof. This is getting uglier. I'd really prefer not to expose all these 
> different internal clocks out userland. Especially via clock_gettime().

Actually, I would be happy to just expose them to modules. As things
like hwlat_detect could use them.

-- Steve


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