Re: [PATCH 1/3] fix debug message of CPU clock speed

[Yasuaki Ishimatsu]

Hi, Ingo

Thank you for your comments.
I apply your comments to the patch ASAP.

Regard,
Yasuaki Ishimatsu

Ingo Molnar wrote:
> * Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> wrote:
>
> > 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 .
>
> your fix looks good, but there are a few minor style details that need to 
> be addressed:
>
> > 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@xxxxxxxxxxxxxx>
> >
> > ---
> >  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)
>
> The cleaner prototype line-width break is:
>
>   + static int __init
>   + calibrate_by_pmtimer(long deltapm, long *delta, long *deltatsc)
>
>
> this function:
>
> > @@ -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;
> > +		}
>
> has too deep nesting in the form of:
>
> 	if (A) {
> 		...
> 	} else {
> 		...
> 		if (B) {
> 			...
> 		}
> 	}
>
> 	return 0;
>
>
> Could you please restructure it to a cleaner control flow, in the form of:
>
> 	if (A) {
> 		...
> 		return 0;
> 	}
> 	...
> 	if (B) {
> 		...
>   	}
>
> 	return 0;
>
> ?
>
> Thanks,
>
> 	Ingo

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