[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: Mark Langsdorf <mark.langsdorf@amd.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Andi 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(-)
diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
index bd3e45d..3421f21 100644
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -843,7 +843,7 @@
} 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);
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 811b8f9..5f862e2 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -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 @@
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 @@
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 @@
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();
diff --git a/arch/x86_64/kernel/tsc.c b/arch/x86_64/kernel/tsc.c
index 1a0edbb..5c84992 100644
--- a/arch/x86_64/kernel/tsc.c
+++ b/arch/x86_64/kernel/tsc.c
@@ -13,6 +13,8 @@
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 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 @@
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 @@
*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 @@
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;
diff --git a/arch/x86_64/kernel/tsc_sync.c b/arch/x86_64/kernel/tsc_sync.c
index 014f0db..72d444d 100644
--- a/arch/x86_64/kernel/tsc_sync.c
+++ b/arch/x86_64/kernel/tsc_sync.c
@@ -50,7 +50,7 @@
/*
* The measurement runs for 20 msecs:
*/
- end = start + cpu_khz * 20ULL;
+ end = start + tsc_khz * 20ULL;
now = start;
for (i = 0; ; i++) {
diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h
index f64949f..7842702 100644
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -92,6 +92,7 @@
extern int exception_trace;
extern unsigned cpu_khz;
+extern unsigned tsc_khz;
extern void no_iommu_init(void);
extern int force_iommu, no_iommu;
