linux-kernel - Re: [PATCH v2 06/17] cpufreq: Fix the efficient idle check for Intel extended Families

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Message-ID: <f162dda5daba3cc96d1bd4f07d710823ffb9eb01.camel@intel.com>
Date: Fri, 14 Feb 2025 02:03:24 +0000
From: "Zhang, Rui" <rui.zhang@...el.com>
To: "Mehta, Sohil" <sohil.mehta@...el.com>, "Luck, Tony"
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Subject: Re: [PATCH v2 06/17] cpufreq: Fix the efficient idle check for Intel
 extended Families

On Thu, 2025-02-13 at 10:49 -0800, Sohil Mehta wrote:
> On 2/11/2025 9:35 PM, Zhang, Rui wrote:
> > >  static int should_io_be_busy(void)
> > >  {
> > >  #if defined(CONFIG_X86)
> > >         /*
> > > -        * For Intel, Core 2 (model 15) and later have an
> > > efficient
> > > idle.
> > > +        * Starting with Family 6 consider all Intel CPUs to have
> > > an
> > > +        * efficient idle.
> > >          */
> > >         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
> > > -                       boot_cpu_data.x86 == 6 &&
> > > -                       boot_cpu_data.x86_model >= 15)
> > > +           boot_cpu_data.x86_vfm >= INTEL_PENTIUM_PRO)
> > 
> > This is "Starting from P4" rather than "Starting from Family 6",
> > right?
> > 
> 
> As described in the commit message, we are extending this to all
> relevant Intel processors. That would include Family 6, Family 15 and
> the upcoming Family > 15 processors as well.
> 
> A VFM check starting at INTEL_PENTIUM_PRO (Family 6, Model 1) is just
> a
> way to simplify that.
> 
You're right. Previously I thought the Fam15 processors are before
Fam6.

-rui