Messages in this thread | | | Date | Fri, 4 Sep 2009 09:49:38 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH: x86] Print the hypervisor returned tsc_khz during boot. |
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* Alok Kataria <akataria@vmware.com> 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@vmware.com> > > 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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