Re: [PATCH v1 2/6] cpufreq: intel_pstate: Do not update global.turbo_disabled after initialization

[srinivas pandruvada <srinivas.pandruvada@linux.intel.com>]

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Hi Xi,

On Sun, 2024-06-02 at 11:21 +0800, Xi Ruoyao wrote:
> On Mon, 2024-03-25 at 18:02 +0100, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > 
> > The global.turbo_disabled is updated quite often, especially in the
> > passive mode in which case it is updated every time the scheduler
> > calls
> > into the driver.  However, this is generally not necessary and it
> > adds
> > MSR read overhead to scheduler code paths (and that particular MSR
> > is
> > slow to read).
> > 
> > For this reason, make the driver read
> > MSR_IA32_MISC_ENABLE_TURBO_DISABLE
> > just once at the cpufreq driver registration time and remove all of
> > the
> > in-flight updates of global.turbo_disabled.
> 
> Hi Rafael and Srinivas,
> 
> Thanks for the clean up, but unfortunately on one of my laptops
> (based
> on i5-11300H) MSR_IA32_MISC_ENABLE_TURBO_DISABLE is mysteriously
> changing from 1 to 0 in about one minute after system boot.  I've no
> idea why this is happening (firmware is doing some stupid thing?)
> 
> I've noticed the issue before and "hacked it around"
> (https://bugzilla.kernel.org/show_bug.cgi?id=218702). But after this
> change I can no longer hack it around and the system is much slower.
> 
> Is it possible to hack it around again?
> 
Please try the attached diff and build kernel and try.

git apply update_max_freq.diff

Then build kernel and install.

Thanks,
Srinivas

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diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 4b986c044741..deab96d8d4bf 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1168,6 +1168,12 @@ static void intel_pstate_update_limits(unsigned int cpu)
 	if (!policy)
 		return;
 
+	pr_info("%s cpu:%d\n", __func__, cpu);
+
+	global.turbo_disabled = turbo_is_disabled();
+	global.no_turbo = global.turbo_disabled;
+	arch_set_max_freq_ratio(global.turbo_disabled);
+
 	__intel_pstate_update_max_freq(all_cpu_data[cpu], policy);
 
 	cpufreq_cpu_release(policy);