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Date: Tue, 27 Jan 2009 17:21:12 +0900
From: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To: linux-kernel@...r.kernel.org
CC: mingo@...hat.com
Subject: [PATCH 1/3] fix debug message of CPU clock speed
LOCAL APIC is corrected by PM-Timer, when SMI occurred while LOCAL APIC is calibrated.
In this case, LOCAL APIC debug message(Boot with apic=debug) is displayed correctly,
however, CPU clock speed debug message is displayed wrongly .
When SMI occured on my machine, which has 1.6GHz CPU, CPU clock speed is displayed
3622.0205 MHz as follow.
CPU0: Intel(R) Xeon(R) CPU 5110 @ 1.60GHz stepping 06
Using local APIC timer interrupts.
calibrating APIC timer ...
... lapic delta = 3773130
... PM timer delta = 812434
APIC calibration not consistent with PM Timer: 226ms instead of 100ms
APIC delta adjusted to PM-Timer: 1662420 (3773130)
..... delta 1662420
..... mult: 71411249
..... calibration result: 265987
..... CPU clock speed is 3622.0205 MHz. =====> here
..... host bus clock speed is 265.0987 MHz.
This patch fixes to displaying CPU clock speed correctly as follow.
CPU0: Intel(R) Xeon(R) CPU 5110 @ 1.60GHz stepping 06
Using local APIC timer interrupts.
calibrating APIC timer ...
... lapic delta = 3773131
... PM timer delta = 812434
APIC calibration not consistent with PM Timer: 226ms instead of 100ms
APIC delta adjusted to PM-Timer: 1662420 (3773131)
TSC delta adjusted to PM-Timer: 159592409 (362220564)
..... delta 1662420
..... mult: 71411249
..... calibration result: 265987
..... CPU clock speed is 1595.0924 MHz.
..... host bus clock speed is 265.0987 MHz.
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
---
arch/x86/kernel/apic.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
Index: linux-2.6.29-rc2/arch/x86/kernel/apic.c
===================================================================
--- linux-2.6.29-rc2.orig/arch/x86/kernel/apic.c 2009-01-27 11:04:40.000000000 +0900
+++ linux-2.6.29-rc2/arch/x86/kernel/apic.c 2009-01-27 12:29:03.000000000 +0900
@@ -535,7 +535,8 @@ static void __init lapic_cal_handler(str
}
}
-static int __init calibrate_by_pmtimer(long deltapm, long *delta)
+static int __init calibrate_by_pmtimer(long deltapm, long *delta,
+ long *deltatsc)
{
const long pm_100ms = PMTMR_TICKS_PER_SEC / 10;
const long pm_thresh = pm_100ms / 100;
@@ -569,6 +570,15 @@ static int __init calibrate_by_pmtimer(l
pr_info("APIC delta adjusted to PM-Timer: "
"%lu (%ld)\n", (unsigned long)res, *delta);
*delta = (long)res;
+
+ if (cpu_has_tsc) {
+ res = (((u64)(*deltatsc)) * pm_100ms);
+ do_div(res, deltapm);
+ apic_printk(APIC_VERBOSE, "TSC delta adjusted to "
+ "PM-Timer: %lu (%ld)\n",
+ (unsigned long)res, *deltatsc);
+ *deltatsc = (long)res;
+ }
}
return 0;
@@ -579,7 +589,7 @@ static int __init calibrate_APIC_clock(v
struct clock_event_device *levt = &__get_cpu_var(lapic_events);
void (*real_handler)(struct clock_event_device *dev);
unsigned long deltaj;
- long delta;
+ long delta, deltatsc;
int pm_referenced = 0;
local_irq_disable();
@@ -609,9 +619,11 @@ static int __init calibrate_APIC_clock(v
delta = lapic_cal_t1 - lapic_cal_t2;
apic_printk(APIC_VERBOSE, "... lapic delta = %ld\n", delta);
+ deltatsc = (long)(lapic_cal_tsc2 - lapic_cal_tsc1);
+
/* we trust the PM based calibration if possible */
pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1,
- &delta);
+ &delta, &deltatsc);
/* Calculate the scaled math multiplication factor */
lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
@@ -629,11 +641,10 @@ static int __init calibrate_APIC_clock(v
calibration_result);
if (cpu_has_tsc) {
- delta = (long)(lapic_cal_tsc2 - lapic_cal_tsc1);
apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
"%ld.%04ld MHz.\n",
- (delta / LAPIC_CAL_LOOPS) / (1000000 / HZ),
- (delta / LAPIC_CAL_LOOPS) % (1000000 / HZ));
+ (deltatsc / LAPIC_CAL_LOOPS) / (1000000 / HZ),
+ (deltatsc / LAPIC_CAL_LOOPS) % (1000000 / HZ));
}
apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
--
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