linux-kernel - [PATCH: x86] Print the hypervisor returned tsc

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Message-Id: <1251076103.29422.32.camel@ank32.eng.vmware.com>
Date:	Sun, 23 Aug 2009 18:08:23 -0700
From:	Alok Kataria <akataria@...are.com>
To:	Ingo Molnar <mingo@...e.hu>,
	the arch/x86 maintainers <x86@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH: x86] Print the hypervisor returned tsc_khz during boot.

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@...are.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;
 	}
 


 


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