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Commit 18b2646f authored by Venkatesh Pallipadi's avatar Venkatesh Pallipadi Committed by Len Brown
Browse files

ACPI x86: Make aperf/mperf MSR access in acpi_cpufreq read_only 



Do not write zeroes to APERF and MPERF by ondemand governor. With this
change, other users can share these MSRs for reads.

Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent e4f69372

arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c

+10 −5
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ struct acpi_cpufreq_data { 
	unsigned int max_freq;

	unsigned int resume;

	unsigned int cpu_feature;

	u64 saved_aperf, saved_mperf;

};



static DEFINE_PER_CPU(struct acpi_cpufreq_data *, drv_data);
@@ -259,9 +260,6 @@ static long read_measured_perf_ctrs(void *_cur) 
	rdmsr(MSR_IA32_APERF, cur->aperf.split.lo, cur->aperf.split.hi);

	rdmsr(MSR_IA32_MPERF, cur->mperf.split.lo, cur->mperf.split.hi);



	wrmsr(MSR_IA32_APERF, 0, 0);

	wrmsr(MSR_IA32_MPERF, 0, 0);



	return 0;

}
@@ -281,13 +279,20 @@ static long read_measured_perf_ctrs(void *_cur) 
static unsigned int get_measured_perf(struct cpufreq_policy *policy,

				      unsigned int cpu)

{

	struct perf_pair cur;

	struct perf_pair readin, cur;

	unsigned int perf_percent;

	unsigned int retval;



	if (!work_on_cpu(cpu, read_measured_perf_ctrs, &cur))

	if (!work_on_cpu(cpu, read_measured_perf_ctrs, &readin))

		return 0;



	cur.aperf.whole = readin.aperf.whole -

				per_cpu(drv_data, cpu)->saved_aperf;

	cur.mperf.whole = readin.mperf.whole -

				per_cpu(drv_data, cpu)->saved_mperf;

	per_cpu(drv_data, cpu)->saved_aperf = readin.aperf.whole;

	per_cpu(drv_data, cpu)->saved_mperf = readin.mperf.whole;



#ifdef __i386__

	/*

	 * We dont want to do 64 bit divide with 32 bit kernel