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* [PATCH] kvm: kvmclock: use get_cpu() and put_cpu()
@ 2014-09-26  6:00 Tiejun Chen
  2014-09-26  8:23 ` Paolo Bonzini
  2014-10-31 15:11 ` Paolo Bonzini
  0 siblings, 2 replies; 3+ messages in thread
From: Tiejun Chen @ 2014-09-26  6:00 UTC (permalink / raw)
  To: pbonzini; +Cc: kvm

We can use get_cpu() and put_cpu() to replace
preempt_disable()/cpu = smp_processor_id() and
preempt_enable() for slightly better code.

Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
---
 arch/x86/kernel/kvmclock.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index d9156ce..0bf3467 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -59,13 +59,12 @@ static void kvm_get_wallclock(struct timespec *now)
 
 	native_write_msr(msr_kvm_wall_clock, low, high);
 
-	preempt_disable();
-	cpu = smp_processor_id();
+	cpu = get_cpu();
 
 	vcpu_time = &hv_clock[cpu].pvti;
 	pvclock_read_wallclock(&wall_clock, vcpu_time, now);
 
-	preempt_enable();
+	put_cpu();
 }
 
 static int kvm_set_wallclock(const struct timespec *now)
@@ -107,11 +106,10 @@ static unsigned long kvm_get_tsc_khz(void)
 	int cpu;
 	unsigned long tsc_khz;
 
-	preempt_disable();
-	cpu = smp_processor_id();
+	cpu = get_cpu();
 	src = &hv_clock[cpu].pvti;
 	tsc_khz = pvclock_tsc_khz(src);
-	preempt_enable();
+	put_cpu();
 	return tsc_khz;
 }
 
@@ -284,23 +282,22 @@ int __init kvm_setup_vsyscall_timeinfo(void)
 
 	size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
 
-	preempt_disable();
-	cpu = smp_processor_id();
+	cpu = get_cpu();
 
 	vcpu_time = &hv_clock[cpu].pvti;
 	flags = pvclock_read_flags(vcpu_time);
 
 	if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
-		preempt_enable();
+		put_cpu();
 		return 1;
 	}
 
 	if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
-		preempt_enable();
+		put_cpu();
 		return ret;
 	}
 
-	preempt_enable();
+	put_cpu();
 
 	kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
 #endif
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] kvm: kvmclock: use get_cpu() and put_cpu()
  2014-09-26  6:00 [PATCH] kvm: kvmclock: use get_cpu() and put_cpu() Tiejun Chen
@ 2014-09-26  8:23 ` Paolo Bonzini
  2014-10-31 15:11 ` Paolo Bonzini
  1 sibling, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2014-09-26  8:23 UTC (permalink / raw)
  To: Tiejun Chen; +Cc: kvm

Il 26/09/2014 08:00, Tiejun Chen ha scritto:
> We can use get_cpu() and put_cpu() to replace
> preempt_disable()/cpu = smp_processor_id() and
> preempt_enable() for slightly better code.
> 
> Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
> ---
>  arch/x86/kernel/kvmclock.c | 19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index d9156ce..0bf3467 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -59,13 +59,12 @@ static void kvm_get_wallclock(struct timespec *now)
>  
>  	native_write_msr(msr_kvm_wall_clock, low, high);
>  
> -	preempt_disable();
> -	cpu = smp_processor_id();
> +	cpu = get_cpu();
>  
>  	vcpu_time = &hv_clock[cpu].pvti;
>  	pvclock_read_wallclock(&wall_clock, vcpu_time, now);
>  
> -	preempt_enable();
> +	put_cpu();
>  }
>  
>  static int kvm_set_wallclock(const struct timespec *now)
> @@ -107,11 +106,10 @@ static unsigned long kvm_get_tsc_khz(void)
>  	int cpu;
>  	unsigned long tsc_khz;
>  
> -	preempt_disable();
> -	cpu = smp_processor_id();
> +	cpu = get_cpu();
>  	src = &hv_clock[cpu].pvti;
>  	tsc_khz = pvclock_tsc_khz(src);
> -	preempt_enable();
> +	put_cpu();
>  	return tsc_khz;
>  }
>  
> @@ -284,23 +282,22 @@ int __init kvm_setup_vsyscall_timeinfo(void)
>  
>  	size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
>  
> -	preempt_disable();
> -	cpu = smp_processor_id();
> +	cpu = get_cpu();
>  
>  	vcpu_time = &hv_clock[cpu].pvti;
>  	flags = pvclock_read_flags(vcpu_time);
>  
>  	if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
> -		preempt_enable();
> +		put_cpu();
>  		return 1;
>  	}
>  
>  	if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
> -		preempt_enable();
> +		put_cpu();
>  		return ret;
>  	}
>  
> -	preempt_enable();
> +	put_cpu();
>  
>  	kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
>  #endif
> 

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

but will wait for 3.19.

Paolo

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH] kvm: kvmclock: use get_cpu() and put_cpu()
  2014-09-26  6:00 [PATCH] kvm: kvmclock: use get_cpu() and put_cpu() Tiejun Chen
  2014-09-26  8:23 ` Paolo Bonzini
@ 2014-10-31 15:11 ` Paolo Bonzini
  1 sibling, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2014-10-31 15:11 UTC (permalink / raw)
  To: Tiejun Chen; +Cc: kvm

On 26/09/2014 08:00, Tiejun Chen wrote:
> We can use get_cpu() and put_cpu() to replace
> preempt_disable()/cpu = smp_processor_id() and
> preempt_enable() for slightly better code.
> 
> Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
> ---
>  arch/x86/kernel/kvmclock.c | 19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index d9156ce..0bf3467 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -59,13 +59,12 @@ static void kvm_get_wallclock(struct timespec *now)
>  
>  	native_write_msr(msr_kvm_wall_clock, low, high);
>  
> -	preempt_disable();
> -	cpu = smp_processor_id();
> +	cpu = get_cpu();
>  
>  	vcpu_time = &hv_clock[cpu].pvti;
>  	pvclock_read_wallclock(&wall_clock, vcpu_time, now);
>  
> -	preempt_enable();
> +	put_cpu();
>  }
>  
>  static int kvm_set_wallclock(const struct timespec *now)
> @@ -107,11 +106,10 @@ static unsigned long kvm_get_tsc_khz(void)
>  	int cpu;
>  	unsigned long tsc_khz;
>  
> -	preempt_disable();
> -	cpu = smp_processor_id();
> +	cpu = get_cpu();
>  	src = &hv_clock[cpu].pvti;
>  	tsc_khz = pvclock_tsc_khz(src);
> -	preempt_enable();
> +	put_cpu();
>  	return tsc_khz;
>  }
>  
> @@ -284,23 +282,22 @@ int __init kvm_setup_vsyscall_timeinfo(void)
>  
>  	size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
>  
> -	preempt_disable();
> -	cpu = smp_processor_id();
> +	cpu = get_cpu();
>  
>  	vcpu_time = &hv_clock[cpu].pvti;
>  	flags = pvclock_read_flags(vcpu_time);
>  
>  	if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
> -		preempt_enable();
> +		put_cpu();
>  		return 1;
>  	}
>  
>  	if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
> -		preempt_enable();
> +		put_cpu();
>  		return ret;
>  	}
>  
> -	preempt_enable();
> +	put_cpu();
>  
>  	kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
>  #endif
> 

Thanks, applied at last.

Paolo

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2014-10-31 16:38 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2014-09-26  6:00 [PATCH] kvm: kvmclock: use get_cpu() and put_cpu() Tiejun Chen
2014-09-26  8:23 ` Paolo Bonzini
2014-10-31 15:11 ` Paolo Bonzini

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