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.

--

Index: linux-tip-master/arch/x86/kernel/tsc.c
===================================================================
@@ -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;
 	}
 

<snip>...

Sure, here is the one which fits on top of current tip.

I also added a print statement for the case where the TSC frequecy cannot be read from vmware's hypervisor.

Thanks.
--

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 the 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 VMware hypervisor returned. Please consider for tip.

---

Index: linux-x86-tree.git/arch/x86/kernel/cpu/vmware.c
===================================================================
@@ -58,6 +58,9 @@ static unsigned long vmware_get_tsc_khz(
 	tsc_hz = eax | (((uint64_t)ebx) << 32);
 	do_div(tsc_hz, 1000);
 	BUG_ON(tsc_hz >> 32);
+	printk(KERN_INFO "TSC freq read from hypervisor : %lu.%03lu MHz\n",
+			 (unsigned long) tsc_hz / 1000,
+			 (unsigned long) tsc_hz % 1000);
 	return tsc_hz;
 }
 

@@ -69,6 +72,9 @@ void __init vmware_platform_setup(void)
 
 	if (ebx != UINT_MAX)
 		x86_platform.calibrate_tsc = vmware_get_tsc_khz;
+	else
+		printk(KERN_WARNING
+		       "Failed to get TSC freq from the hypervisor\n");
 }
 
 /*

Commit-ID:  6399c087458859cddff2d6b46befb95b866df3e0
Gitweb:     http://git.kernel.org/tip/6399c087458859cddff2d6b46befb95b866df3e0
Author:     Alok Kataria <[email protected]>
AuthorDate: Fri, 4 Sep 2009 13:13:39 -0700
Committer:  Ingo Molnar <[email protected]>
CommitDate: Sun, 20 Sep 2009 20:25:36 +0200

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 the 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 VMware hypervisor returned.

LKML-Reference: <[email protected]>

---
 arch/x86/kernel/cpu/vmware.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

index 0a46b4d..1cbed97 100644
@@ -58,6 +58,9 @@ static unsigned long vmware_get_tsc_khz(void)
 	tsc_hz = eax | (((uint64_t)ebx) << 32);
 	do_div(tsc_hz, 1000);
 	BUG_ON(tsc_hz >> 32);
+	printk(KERN_INFO "TSC freq read from hypervisor : %lu.%03lu MHz\n",
+			 (unsigned long) tsc_hz / 1000,
+			 (unsigned long) tsc_hz % 1000);
 	return tsc_hz;
 }
 

@@ -69,6 +72,9 @@ void __init vmware_platform_setup(void)
 
 	if (ebx != UINT_MAX)
 		x86_platform.calibrate_tsc = vmware_get_tsc_khz;
+	else
+		printk(KERN_WARNING
+		       "Failed to get TSC freq from the hypervisor\n");
 }
 
 /*