Messages in this thread Patch in this message | | | Date | Tue, 27 Jan 2009 17:21:12 +0900 | From | Yasuaki Ishimatsu <> | Subject | [PATCH 1/3] fix debug message of CPU clock speed |
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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@jp.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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