* [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var
@ 2012-11-19 5:21 Shan Wei
2012-11-19 21:34 ` Christoph Lameter
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Shan Wei @ 2012-11-19 5:21 UTC (permalink / raw)
To: rostedt, fweisbec, mingo, Kernel-Maillist, Christoph Lameter
From: Shan Wei <davidshan@tencent.com>
__this_cpu_inc_return() or __this_cpu_dec generates a single instruction,
which is faster than __get_cpu_var operation.
Signed-off-by: Shan Wei <davidshan@tencent.com>
---
kernel/trace/trace.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 18c0aa8..3795694 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1313,7 +1313,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
*/
preempt_disable_notrace();
- use_stack = ++__get_cpu_var(ftrace_stack_reserve);
+ use_stack = __this_cpu_inc_return(ftrace_stack_reserve);
/*
* We don't need any atomic variables, just a barrier.
* If an interrupt comes in, we don't care, because it would
@@ -1367,7 +1367,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
out:
/* Again, don't let gcc optimize things here */
barrier();
- __get_cpu_var(ftrace_stack_reserve)--;
+ __this_cpu_dec(ftrace_stack_reserve);
preempt_enable_notrace();
}
--
1.7.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var
2012-11-19 5:21 [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var Shan Wei
@ 2012-11-19 21:34 ` Christoph Lameter
2012-11-30 6:37 ` Shan Wei
2013-02-03 19:18 ` [tip:perf/core] tracing: Use __this_cpu_inc/ dec " tip-bot for Shan Wei
2 siblings, 0 replies; 4+ messages in thread
From: Christoph Lameter @ 2012-11-19 21:34 UTC (permalink / raw)
To: Shan Wei; +Cc: rostedt, fweisbec, mingo, Kernel-Maillist
On Mon, 19 Nov 2012, Shan Wei wrote:
> __this_cpu_inc_return() or __this_cpu_dec generates a single instruction,
> which is faster than __get_cpu_var operation.
Reviewed-by: Christoph Lameter <cl@linux.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var
2012-11-19 5:21 [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var Shan Wei
2012-11-19 21:34 ` Christoph Lameter
@ 2012-11-30 6:37 ` Shan Wei
2013-02-03 19:18 ` [tip:perf/core] tracing: Use __this_cpu_inc/ dec " tip-bot for Shan Wei
2 siblings, 0 replies; 4+ messages in thread
From: Shan Wei @ 2012-11-30 6:37 UTC (permalink / raw)
To: rostedt, fweisbec, mingo, Kernel-Maillist, Christoph Lameter
ping ......
Shan Wei said, at 2012/11/19 13:21:
> From: Shan Wei <davidshan@tencent.com>
>
> __this_cpu_inc_return() or __this_cpu_dec generates a single instruction,
> which is faster than __get_cpu_var operation.
>
> Signed-off-by: Shan Wei <davidshan@tencent.com>
> ---
> kernel/trace/trace.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 18c0aa8..3795694 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1313,7 +1313,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
> */
> preempt_disable_notrace();
>
> - use_stack = ++__get_cpu_var(ftrace_stack_reserve);
> + use_stack = __this_cpu_inc_return(ftrace_stack_reserve);
> /*
> * We don't need any atomic variables, just a barrier.
> * If an interrupt comes in, we don't care, because it would
> @@ -1367,7 +1367,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
> out:
> /* Again, don't let gcc optimize things here */
> barrier();
> - __get_cpu_var(ftrace_stack_reserve)--;
> + __this_cpu_dec(ftrace_stack_reserve);
> preempt_enable_notrace();
>
> }
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [tip:perf/core] tracing: Use __this_cpu_inc/ dec operation instead of __get_cpu_var
2012-11-19 5:21 [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var Shan Wei
2012-11-19 21:34 ` Christoph Lameter
2012-11-30 6:37 ` Shan Wei
@ 2013-02-03 19:18 ` tip-bot for Shan Wei
2 siblings, 0 replies; 4+ messages in thread
From: tip-bot for Shan Wei @ 2013-02-03 19:18 UTC (permalink / raw)
To: linux-tip-commits; +Cc: linux-kernel, hpa, mingo, davidshan, rostedt, cl, tglx
Commit-ID: 821465295b36136998ef294fe176fba4e09c1cd9
Gitweb: http://git.kernel.org/tip/821465295b36136998ef294fe176fba4e09c1cd9
Author: Shan Wei <davidshan@tencent.com>
AuthorDate: Mon, 19 Nov 2012 13:21:01 +0800
Committer: Steven Rostedt <rostedt@goodmis.org>
CommitDate: Fri, 25 Jan 2013 20:36:54 -0500
tracing: Use __this_cpu_inc/dec operation instead of __get_cpu_var
__this_cpu_inc_return() or __this_cpu_dec generates a single instruction,
which is faster than __get_cpu_var operation.
Link: http://lkml.kernel.org/r/50A9C1BD.1060308@gmail.com
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Shan Wei <davidshan@tencent.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ca9b7df..07888e1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1344,7 +1344,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
*/
preempt_disable_notrace();
- use_stack = ++__get_cpu_var(ftrace_stack_reserve);
+ use_stack = __this_cpu_inc_return(ftrace_stack_reserve);
/*
* We don't need any atomic variables, just a barrier.
* If an interrupt comes in, we don't care, because it would
@@ -1398,7 +1398,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
out:
/* Again, don't let gcc optimize things here */
barrier();
- __get_cpu_var(ftrace_stack_reserve)--;
+ __this_cpu_dec(ftrace_stack_reserve);
preempt_enable_notrace();
}
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-02-03 19:18 UTC | newest]
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2012-11-19 5:21 [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var Shan Wei
2012-11-19 21:34 ` Christoph Lameter
2012-11-30 6:37 ` Shan Wei
2013-02-03 19:18 ` [tip:perf/core] tracing: Use __this_cpu_inc/ dec " tip-bot for Shan Wei
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