linux-kernel - Re: [PATCH 2/4 v2] x86: use common aperfmperf_khz_on

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Message-ID: <alpine.DEB.2.20.1706241052050.1941@nanos>
Date:   Sat, 24 Jun 2017 10:56:40 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Len Brown <lenb@...nel.org>
cc:     rafael@...nel.org, x86@...nel.org,
        srinivas.pandruvada@...ux.intel.com, peterz@...radead.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Len Brown <len.brown@...el.com>
Subject: Re: [PATCH 2/4 v2] x86: use common aperfmperf_khz_on_cpu() to
 calculate KHz using APERF/MPERF

On Fri, 23 Jun 2017, Len Brown wrote:
> This x86 native method to calculate MHz returns a meaningful result
> no matter if P-states are controlled by hardware or firmware
> and/or if the Linux cpufreq sub-system is or is-not installed.
> 
> When this routine is invoked more frequently, the measurement
> interval becomes shorter.  However, the code limits re-computation
> to 10ms intervals so that average frequency remains meaningful.
> 
> Discerning users are encouraged to take advantage of
> the turbostat(8) utility, which can gracefully handle
> concurrent measurement intervals of arbitrary length.
> 
> Signed-off-by: Len Brown <len.brown@...el.com>

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>

Raphael, please take the whole lot through the cpufreq tree.

Thanks,

	tglx