linux-kernel - Re: [PATCH v1 1/2] cpufreq: intel_pstate: Use CPPC to get scaling factors

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Message-ID: <b1bc2569b0da4c6749e896eee0fdf0af97c18fea.camel@linux.intel.com>
Date: Thu, 01 May 2025 10:13:01 -0700
From: srinivas pandruvada <srinivas.pandruvada@...ux.intel.com>
To: Russell Haley <yumpusamongus@...il.com>, "Rafael J. Wysocki"
	 <rjw@...ysocki.net>, Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 1/2] cpufreq: intel_pstate: Use CPPC to get scaling
 factors

Hi Russell,


On Wed, 2025-04-30 at 20:28 -0500, Russell Haley wrote:
> 
> On 12/5/24 5:39 AM, Rafael J. Wysocki wrote:
> 
> > +	 * Compute the perf-to-frequency scaling factor for the
> > given CPU if
> > +	 * possible, unless it would be 0.
> > +	 */
> > +	if (!cppc_get_perf_caps(cpu, &cppc_perf) &&
> > +	    cppc_perf.nominal_perf && cppc_perf.nominal_freq)
> > +		return div_u64(cppc_perf.nominal_freq *
> > KHZ_PER_MHZ,
> > +			       cppc_perf.nominal_perf);
> 
Can you dump the output of

 grep -r . /sys/devices/system/cpu/cpu*/acpi_cppc/

Thanks,
Srinivas

> I think this exposed a firmware bug on ARL. I have a Core Ultra 265K,
> and two of the E-cores report 33 for nominal_perf, while the others
> report 46. They all report 3300 for nominal_freq.
> 
> The result is that the kernel thinks these two E-cores are capable of
> 6.5 GHz.
> 
> > grep . /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_max_freq
> /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq:5400000
> /sys/devices/system/cpu/cpu1/cpufreq/cpuinfo_max_freq:5500000
> /sys/devices/system/cpu/cpu2/cpufreq/cpuinfo_max_freq:5400000
> /sys/devices/system/cpu/cpu3/cpufreq/cpuinfo_max_freq:5400000
> /sys/devices/system/cpu/cpu4/cpufreq/cpuinfo_max_freq:5400000
> /sys/devices/system/cpu/cpu5/cpufreq/cpuinfo_max_freq:5400000
> /sys/devices/system/cpu/cpu6/cpufreq/cpuinfo_max_freq:5400000
> /sys/devices/system/cpu/cpu7/cpufreq/cpuinfo_max_freq:5500000
> /sys/devices/system/cpu/cpu8/cpufreq/cpuinfo_max_freq:4600000
> /sys/devices/system/cpu/cpu9/cpufreq/cpuinfo_max_freq:4600000
> /sys/devices/system/cpu/cpu10/cpufreq/cpuinfo_max_freq:4600000
> /sys/devices/system/cpu/cpu11/cpufreq/cpuinfo_max_freq:4600000
> /sys/devices/system/cpu/cpu12/cpufreq/cpuinfo_max_freq:6500000 # wow
> /sys/devices/system/cpu/cpu13/cpufreq/cpuinfo_max_freq:6500000 #
> amazing
> /sys/devices/system/cpu/cpu14/cpufreq/cpuinfo_max_freq:4600000
> /sys/devices/system/cpu/cpu15/cpufreq/cpuinfo_max_freq:4600000
> /sys/devices/system/cpu/cpu16/cpufreq/cpuinfo_max_freq:4600000
> /sys/devices/system/cpu/cpu17/cpufreq/cpuinfo_max_freq:4600000
> /sys/devices/system/cpu/cpu18/cpufreq/cpuinfo_max_freq:4600000
> /sys/devices/system/cpu/cpu19/cpufreq/cpuinfo_max_freq:4600000
> 
> Hopefully you have the ear of someone on the firmware team so that a
> ticket can be created for this.
> 
> In Phoronix discussion, users have reported seeing this on both
> ASRock
> and MSI motherboards:
> 
> https://www.phoronix.com/forums/forum/hardware/processors-memory/1541981-intel-core-ultra-9-285k-arrow-lake-performance-on-linux-has-improved-a-lot-since-launch?p=1543676#post1543676
> 
> ----------
> 
> Also, this may be related... I can't set scaling_max_freq to odd
> multiples of 100 MHz, only even. Checking with:
> 
>     x86_energy_perf_policy &| grep -i req
> 
> reveals that some values of max are being skipped. Setting manually
> with
> 
>     x86_energy_perf_policy --cpu 0-7 --hwp-max 76
> 
> allows the odd multiples to be accessed. Integer division issue
> somewhere?
>