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

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

[Alok Kataria]

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;
 	}
 


 

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

[Ingo Molnar]

* 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

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

[Alok Kataria]

<snip>...

> 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?

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.

---
Signed-off-by: Alok N Kataria <akataria@vmware.com>

Index: linux-x86-tree.git/arch/x86/kernel/cpu/vmware.c
===================================================================
--- linux-x86-tree.git.orig/arch/x86/kernel/cpu/vmware.c	2009-09-04 12:59:45.000000000 -0700
+++ linux-x86-tree.git/arch/x86/kernel/cpu/vmware.c	2009-09-04 13:01:41.000000000 -0700
@@ -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");
 }
 
 /*

[tip:x86/urgent] x86: Print the hypervisor returned tsc_khz during boot

[tip-bot for Alok Kataria]

Commit-ID:  6399c087458859cddff2d6b46befb95b866df3e0
Gitweb:     http://git.kernel.org/tip/6399c087458859cddff2d6b46befb95b866df3e0
Author:     Alok Kataria <akataria@vmware.com>
AuthorDate: Fri, 4 Sep 2009 13:13:39 -0700
Committer:  Ingo Molnar <mingo@elte.hu>
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.

Signed-off-by: Alok N Kataria <akataria@vmware.com>
LKML-Reference: <1252095219.12518.13.camel@ank32.eng.vmware.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


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

diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 0a46b4d..1cbed97 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -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");
 }
 
 /*