Re: [PATCH: x86] Print the hypervisor returned tsc_khz during boot.

[Ingo Molnar]

* Alok Kataria <akataria@xxxxxxxxxx> wrote:

> On an AMD-64 system the processor frequency that is printed during 
> system boot, may be different than the tsc frequency that was 
> returned by the hypervisor, due to value returned from 
> calibrate_cpu. For debugging timekeeping or other related issues 
> it might be better to get the tsc_khz value returned by the 
> hypervisor.
> 
> The patch below now prints the tsc frequency that the hypervisor 
> returned. Please consider for tip.
> 
> --
> Signed-off-by: Alok N Kataria <akataria@xxxxxxxxxx>
> 
> Index: linux-tip-master/arch/x86/kernel/tsc.c
> ===================================================================
> --- linux-tip-master.orig/arch/x86/kernel/tsc.c	2009-08-23 17:53:44.000000000 -0700
> +++ linux-tip-master/arch/x86/kernel/tsc.c	2009-08-23 17:55:08.000000000 -0700
> @@ -405,7 +405,10 @@ unsigned long native_calibrate_tsc(void)
>  
>  	hv_tsc_khz = get_hypervisor_tsc_freq();
>  	if (hv_tsc_khz) {
> -		printk(KERN_INFO "TSC: Frequency read from the hypervisor\n");
> +		printk(KERN_INFO "TSC: Frequency read from the hypervisor : "
> +				"%lu.%03lu MHz\n",
> +				(unsigned long) hv_tsc_khz / 1000,
> +				(unsigned long) hv_tsc_khz % 1000);
>  		return hv_tsc_khz;
>  	}

Makes sense. Note, arch/x86/kernel/tsc.c changed recently so this 
patch does not apply anymore - mind merging it on top of that and 
re-send it?

Thanks,

	Ingo
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