[PATCH -tip] perf_counter/x86: Remove masking and unmasking of LVT error register.

[PATCH -tip] perf_counter/x86: Remove masking and unmasking of LVT error register.

[Yong Wang]

Masking and unmasking of LVT error register become unnecessary as NMI mode will be
used all the time.

Signed-off-by: Yong Wang <yong.y.wang@intel.com>

---
 perf_counter.c |    6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 2eeaa99..444bcf2 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -865,22 +865,16 @@ void set_perf_counter_pending(void)
 
 void perf_counters_lapic_init(int nmi)
 {
-	u32 apic_val;
-
 	if (!x86_pmu_initialized())
 		return;
 
 	/*
 	 * Enable the performance counter vector in the APIC LVT:
 	 */
-	apic_val = apic_read(APIC_LVTERR);
-
-	apic_write(APIC_LVTERR, apic_val | APIC_LVT_MASKED);
 	if (nmi)
 		apic_write(APIC_LVTPC, APIC_DM_NMI);
 	else
 		apic_write(APIC_LVTPC, LOCAL_PERF_VECTOR);
-	apic_write(APIC_LVTERR, apic_val);
 }
 
 static int __kprobes

Re: [PATCH -tip] perf_counter/x86: Remove masking and unmasking of LVT error register.

[Ingo Molnar]

* Yong Wang <yong.y.wang@linux.intel.com> wrote:

> Masking and unmasking of LVT error register become unnecessary as 
> NMI mode will be used all the time.
> 
> Signed-off-by: Yong Wang <yong.y.wang@intel.com>
> 
> ---
>  perf_counter.c |    6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
> index 2eeaa99..444bcf2 100644
> --- a/arch/x86/kernel/cpu/perf_counter.c
> +++ b/arch/x86/kernel/cpu/perf_counter.c
> @@ -865,22 +865,16 @@ void set_perf_counter_pending(void)
>  
>  void perf_counters_lapic_init(int nmi)
>  {
> -	u32 apic_val;
> -
>  	if (!x86_pmu_initialized())
>  		return;
>  
>  	/*
>  	 * Enable the performance counter vector in the APIC LVT:
>  	 */
> -	apic_val = apic_read(APIC_LVTERR);
> -
> -	apic_write(APIC_LVTERR, apic_val | APIC_LVT_MASKED);
>  	if (nmi)
>  		apic_write(APIC_LVTPC, APIC_DM_NMI);
>  	else
>  		apic_write(APIC_LVTPC, LOCAL_PERF_VECTOR);
> -	apic_write(APIC_LVTERR, apic_val);
>  }

i'd suggest to remove the 'nmi' parameter as well to this function. 
(and any other dynamic flags that deal with nmi/irq distinctions)

	Ingo

Re: [PATCH -tip] perf_counter/x86: Remove masking and unmasking of LVT error register.

[Yong Wang]

On Thu, May 28, 2009 at 10:33:40AM +0200, Ingo Molnar wrote:
> i'd suggest to remove the 'nmi' parameter as well to this function. 

Thanks for the comment. Just resubmitted a new patch removing the 'nmi'
parameter.

> (and any other dynamic flags that deal with nmi/irq distinctions)

Just wanna make sure before moving on. You want to remove things like
the 'nmi' field in perf_counter_hw_event and hw_perf_counter structs and
the 'nmi' parameter of perf_counter_overflow and perf_swcounter_event
functions, etc. Right?

Thanks
-Yong

Re: [PATCH -tip] perf_counter/x86: Remove masking and unmasking of LVT error register.

[Ingo Molnar]

* Yong Wang <yong.y.wang@linux.intel.com> wrote:

> On Thu, May 28, 2009 at 10:33:40AM +0200, Ingo Molnar wrote:
> > i'd suggest to remove the 'nmi' parameter as well to this function. 
> 
> Thanks for the comment. Just resubmitted a new patch removing the 
> 'nmi' parameter.

applied, thanks!

> > (and any other dynamic flags that deal with nmi/irq 
> > distinctions)
> 
> Just wanna make sure before moving on. You want to remove things 
> like the 'nmi' field in perf_counter_hw_event and hw_perf_counter 
> structs and the 'nmi' parameter of perf_counter_overflow and 
> perf_swcounter_event functions, etc. Right?

yes, that too.

	Ingo