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Commit 82146529 authored by Shan Wei's avatar Shan Wei Committed by Steven Rostedt
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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: default avatarChristoph Lameter <cl@linux.com>
Signed-off-by: default avatarShan Wei <davidshan@tencent.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent d75f717e

kernel/trace/trace.c

+2 −2
Original line number Diff line number Diff line
@@ -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();



}