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tracing: Use __this_cpu_inc/dec operation instead of __get_cpu_var

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__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>
This commit is contained in:
Shan Wei 2012-11-19 13:21:01 +08:00 committed by Steven Rostedt
parent d75f717e19
commit 821465295b
1 changed files with 2 additions and 2 deletions
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4
kernel/trace/trace.c
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@ -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();
}