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Commit 6b37f5a2 authored by Joerg Roedel's avatar Joerg Roedel Committed by Andi Kleen
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[PATCH] x86-64: fix cpu MHz reporting on constant_tsc cpus 



This patch fixes the reporting of cpu_mhz in /proc/cpuinfo on CPUs with
a constant TSC rate and a kernel with disabled cpufreq.

Signed-off-by: default avatarMark Langsdorf <mark.langsdorf@amd.com>
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>

 arch/x86_64/kernel/apic.c     |    2 -
 arch/x86_64/kernel/time.c     |   58 +++++++++++++++++++++++++++++++++++++++---
 arch/x86_64/kernel/tsc.c      |   12 +++++---
 arch/x86_64/kernel/tsc_sync.c |    2 -
 include/asm-x86_64/proto.h    |    1
 5 files changed, 65 insertions(+), 10 deletions(-)
parent fbc16f2c

arch/x86_64/kernel/apic.c

+1 −1
Original line number Diff line number Diff line
@@ -843,7 +843,7 @@ static int __init calibrate_APIC_clock(void) 
		} while ((tsc - tsc_start) < TICK_COUNT &&

				(apic - apic_start) < TICK_COUNT);



		result = (apic_start - apic) * 1000L * cpu_khz /

		result = (apic_start - apic) * 1000L * tsc_khz /

					(tsc - tsc_start);

	}

	printk("result %d\n", result);

arch/x86_64/kernel/time.c

+55 −3
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
#include <asm/apic.h>

#include <asm/hpet.h>

#include <asm/mpspec.h>

#include <asm/nmi.h>



static char *timename = NULL;
@@ -249,6 +250,51 @@ static unsigned long get_cmos_time(void) 
	return mktime(year, mon, day, hour, min, sec);

}



/* calibrate_cpu is used on systems with fixed rate TSCs to determine

 * processor frequency */

#define TICK_COUNT 100000000

static unsigned int __init tsc_calibrate_cpu_khz(void)

{

       int tsc_start, tsc_now;

       int i, no_ctr_free;

       unsigned long evntsel3 = 0, pmc3 = 0, pmc_now = 0;

       unsigned long flags;



       for (i = 0; i < 4; i++)

               if (avail_to_resrv_perfctr_nmi_bit(i))

                       break;

       no_ctr_free = (i == 4);

       if (no_ctr_free) {

               i = 3;

               rdmsrl(MSR_K7_EVNTSEL3, evntsel3);

               wrmsrl(MSR_K7_EVNTSEL3, 0);

               rdmsrl(MSR_K7_PERFCTR3, pmc3);

       } else {

               reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i);

               reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i);

       }

       local_irq_save(flags);

       /* start meauring cycles, incrementing from 0 */

       wrmsrl(MSR_K7_PERFCTR0 + i, 0);

       wrmsrl(MSR_K7_EVNTSEL0 + i, 1 << 22 | 3 << 16 | 0x76);

       rdtscl(tsc_start);

       do {

               rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);

               tsc_now = get_cycles_sync();

       } while ((tsc_now - tsc_start) < TICK_COUNT);



       local_irq_restore(flags);

       if (no_ctr_free) {

               wrmsrl(MSR_K7_EVNTSEL3, 0);

               wrmsrl(MSR_K7_PERFCTR3, pmc3);

               wrmsrl(MSR_K7_EVNTSEL3, evntsel3);

       } else {

               release_perfctr_nmi(MSR_K7_PERFCTR0 + i);

               release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);

       }



       return pmc_now * tsc_khz / (tsc_now - tsc_start);

}



/*

 * pit_calibrate_tsc() uses the speaker output (channel 2) of
@@ -336,14 +382,20 @@ void __init time_init(void) 
	if (hpet_use_timer) {

		/* set tick_nsec to use the proper rate for HPET */

	  	tick_nsec = TICK_NSEC_HPET;

		cpu_khz = hpet_calibrate_tsc();

		tsc_khz = hpet_calibrate_tsc();

		timename = "HPET";

	} else {

		pit_init();

		cpu_khz = pit_calibrate_tsc();

		tsc_khz = pit_calibrate_tsc();

		timename = "PIT";

	}



	cpu_khz = tsc_khz;

	if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&

		boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&

		boot_cpu_data.x86 == 16)

		cpu_khz = tsc_calibrate_cpu_khz();



	if (unsynchronized_tsc())

		mark_tsc_unstable();
@@ -352,7 +404,7 @@ void __init time_init(void) 
	else

		vgetcpu_mode = VGETCPU_LSL;



	set_cyc2ns_scale(cpu_khz);

	set_cyc2ns_scale(tsc_khz);

	printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",

		cpu_khz / 1000, cpu_khz % 1000);

	init_tsc_clocksource();

arch/x86_64/kernel/tsc.c

+7 −5
Original line number Diff line number Diff line
@@ -13,6 +13,8 @@ static int notsc __initdata = 0; 


unsigned int cpu_khz;		/* TSC clocks / usec, not used here */

EXPORT_SYMBOL(cpu_khz);

unsigned int tsc_khz;

EXPORT_SYMBOL(tsc_khz);



static unsigned int cyc2ns_scale __read_mostly;
@@ -77,7 +79,7 @@ static void handle_cpufreq_delayed_get(struct work_struct *v) 
static unsigned int  ref_freq = 0;

static unsigned long loops_per_jiffy_ref = 0;



static unsigned long cpu_khz_ref = 0;

static unsigned long tsc_khz_ref = 0;



static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,

				 void *data)
@@ -99,7 +101,7 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 
	if (!ref_freq) {

		ref_freq = freq->old;

		loops_per_jiffy_ref = *lpj;

		cpu_khz_ref = cpu_khz;

		tsc_khz_ref = tsc_khz;

	}

	if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||

		(val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
@@ -107,12 +109,12 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 
		*lpj =

		cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);



		cpu_khz = cpufreq_scale(cpu_khz_ref, ref_freq, freq->new);

		tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);

		if (!(freq->flags & CPUFREQ_CONST_LOOPS))

			mark_tsc_unstable();

	}



	set_cyc2ns_scale(cpu_khz_ref);

	set_cyc2ns_scale(tsc_khz_ref);



	return 0;

}
@@ -213,7 +215,7 @@ EXPORT_SYMBOL_GPL(mark_tsc_unstable); 
void __init init_tsc_clocksource(void)

{

	if (!notsc) {

		clocksource_tsc.mult = clocksource_khz2mult(cpu_khz,

		clocksource_tsc.mult = clocksource_khz2mult(tsc_khz,

							clocksource_tsc.shift);

		if (check_tsc_unstable())

			clocksource_tsc.rating = 0;

arch/x86_64/kernel/tsc_sync.c

+1 −1
Original line number Diff line number Diff line
@@ -50,7 +50,7 @@ static __cpuinit void check_tsc_warp(void) 
	/*

	 * The measurement runs for 20 msecs:

	 */

	end = start + cpu_khz * 20ULL;

	end = start + tsc_khz * 20ULL;

	now = start;



	for (i = 0; ; i++) {

include/asm-x86_64/proto.h

+1 −0
Original line number Diff line number Diff line
@@ -92,6 +92,7 @@ extern unsigned long table_start, table_end; 


extern int exception_trace;

extern unsigned cpu_khz;

extern unsigned tsc_khz;



extern void no_iommu_init(void);

extern int force_iommu, no_iommu;