[PATCH] x86, tlb: small cleanup for native_flush_tlb_others

[PATCH] x86, tlb: small cleanup for native_flush_tlb_others

[Xiao Guangrong]

Use smp_processor_id instead of get_cpu and put_cpu since
the caller has already disabled preemption

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
 arch/x86/mm/tlb.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 6acc724..92849d0 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -211,11 +211,10 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
 	if (is_uv_system()) {
 		unsigned int cpu;
 
-		cpu = get_cpu();
+		cpu = smp_processor_id();
 		cpumask = uv_flush_tlb_others(cpumask, mm, va, cpu);
 		if (cpumask)
 			flush_tlb_others_ipi(cpumask, mm, va);
-		put_cpu();
 		return;
 	}
 	flush_tlb_others_ipi(cpumask, mm, va);
-- 
1.7.4

Re: [PATCH] x86, tlb: small cleanup for native_flush_tlb_others

[Ingo Molnar]

* Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> wrote:

> Use smp_processor_id instead of get_cpu and put_cpu since
> the caller has already disabled preemption
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> ---
>  arch/x86/mm/tlb.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
> index 6acc724..92849d0 100644
> --- a/arch/x86/mm/tlb.c
> +++ b/arch/x86/mm/tlb.c
> @@ -211,11 +211,10 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
>  	if (is_uv_system()) {
>  		unsigned int cpu;
>  
> -		cpu = get_cpu();
> +		cpu = smp_processor_id();
>  		cpumask = uv_flush_tlb_others(cpumask, mm, va, cpu);
>  		if (cpumask)
>  			flush_tlb_others_ipi(cpumask, mm, va);
> -		put_cpu();
>  		return;

There's multiple callers. Could you please update the changelog with the list of 
callers and a statement that all of them disable preemption already?

Thanks,

	Ingo

Re: [PATCH] x86, tlb: small cleanup for native_flush_tlb_others

[Ingo Molnar]

Also, the title of the patch should be something like 'small micro-optimization' - 
as it's not just a cleanup, it has side-effects on the code.

Thanks,

	Ingo

Re: [PATCH] x86, tlb: small cleanup for native_flush_tlb_others

[Xiao Guangrong]

On 03/14/2011 08:33 PM, Ingo Molnar wrote:
> 
> * Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> wrote:
> 
>> Use smp_processor_id instead of get_cpu and put_cpu since
>> the caller has already disabled preemption
>>
>> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
>> ---
>>  arch/x86/mm/tlb.c |    3 +--
>>  1 files changed, 1 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
>> index 6acc724..92849d0 100644
>> --- a/arch/x86/mm/tlb.c
>> +++ b/arch/x86/mm/tlb.c
>> @@ -211,11 +211,10 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
>>  	if (is_uv_system()) {
>>  		unsigned int cpu;
>>  
>> -		cpu = get_cpu();
>> +		cpu = smp_processor_id();
>>  		cpumask = uv_flush_tlb_others(cpumask, mm, va, cpu);
>>  		if (cpumask)
>>  			flush_tlb_others_ipi(cpumask, mm, va);
>> -		put_cpu();
>>  		return;
> 
> There's multiple callers. Could you please update the changelog with the list of 
> callers and a statement that all of them disable preemption already?
> 

Thanks Ingo, there is the new version.

From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Subject: [PATCH] x86, tlb: small micro-optimization for native_flush_tlb_others

native_flush_tlb_others is called from:
flush_tlb_current_task
flush_tlb_mm
flush_tlb_page

All these functions disable preemption explicitly, so we can use smp_processor_id
instead of get_cpu and put_cpu

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
 arch/x86/mm/tlb.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 6acc724..92849d0 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -211,11 +211,10 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
 	if (is_uv_system()) {
 		unsigned int cpu;
 
-		cpu = get_cpu();
+		cpu = smp_processor_id();
 		cpumask = uv_flush_tlb_others(cpumask, mm, va, cpu);
 		if (cpumask)
 			flush_tlb_others_ipi(cpumask, mm, va);
-		put_cpu();
 		return;
 	}
 	flush_tlb_others_ipi(cpumask, mm, va);
-- 
1.7.4

[tip:x86/mm] x86, tlb, UV: Do small micro-optimization for native_flush_tlb_others()

[tip-bot for Xiao Guangrong]

Commit-ID:  25542c646afbf14c43fa7d2b443055cadb73b07a
Gitweb:     http://git.kernel.org/tip/25542c646afbf14c43fa7d2b443055cadb73b07a
Author:     Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
AuthorDate: Tue, 15 Mar 2011 09:57:37 +0800
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 15 Mar 2011 08:30:34 +0100

x86, tlb, UV: Do small micro-optimization for native_flush_tlb_others()

native_flush_tlb_others() is called from:

 flush_tlb_current_task()
 flush_tlb_mm()
 flush_tlb_page()

All these functions disable preemption explicitly, so we can use
smp_processor_id() instead of get_cpu() and put_cpu().

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Cliff Wickman <cpw@sgi.com>
LKML-Reference: <4D7EC791.4040003@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/mm/tlb.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 55272d7..d6c0418 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -208,11 +208,10 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
 	if (is_uv_system()) {
 		unsigned int cpu;
 
-		cpu = get_cpu();
+		cpu = smp_processor_id();
 		cpumask = uv_flush_tlb_others(cpumask, mm, va, cpu);
 		if (cpumask)
 			flush_tlb_others_ipi(cpumask, mm, va);
-		put_cpu();
 		return;
 	}
 	flush_tlb_others_ipi(cpumask, mm, va);