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

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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: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Venkatesh Pallipadi 2009-04-06 11:26:08 -07:00 committed by Len Brown
parent e4f6937222
commit 18b2646fe3
1 changed files with 10 additions and 5 deletions
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15
arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
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@ -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