linux-kernel - Re: [PATCH RFC] perf: x86: Improve accuracy of perf/sched clock

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Date:	Fri, 24 Jul 2015 17:03:01 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org,
	Stephane Eranian <eranian@...gle.com>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH RFC] perf: x86: Improve accuracy of perf/sched clock

On Fri, Jul 24, 2015 at 04:39:55PM +0300, Adrian Hunter wrote:
> @@ -251,17 +253,17 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
>  	rdtscll(tsc_now);
>  	ns_now = cycles_2_ns(tsc_now);
>  
> -	/*
> -	 * Compute a new multiplier as per the above comment and ensure our
> -	 * time function is continuous; see the comment near struct
> -	 * cyc2ns_data.
> -	 */

I'd leave this comment, but update the one this refers to; esp. the bit
that explains why 10.

Also, I think you can remove the definition of CYC2NS_SCALE_FACTOR.

Other than that, seems like a good idea.
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