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From: Alok Kataria <akataria@vmware.com>
To: Ingo Molnar <mingo@elte.hu>, the arch/x86 maintainers <x86@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH: x86] Print the hypervisor returned tsc_khz during boot.
Date: Sun, 23 Aug 2009 18:08:23 -0700	[thread overview]
Message-ID: <1251076103.29422.32.camel@ank32.eng.vmware.com> (raw)

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;
 	}
 


 



             reply	other threads:[~2009-08-24  1:08 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-08-24  1:08 Alok Kataria [this message]
2009-09-04  7:49 ` Ingo Molnar
2009-09-04 20:13   ` Alok Kataria
2009-09-20 18:30     ` [tip:x86/urgent] x86: " tip-bot for Alok Kataria

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