Messages in this thread Patch in this message | | | Date | Sat, 02 Feb 2013 09:18:45 -0500 | From | Steven Rostedt <> | Subject | [PATCH 03/11] tracing: Use __this_cpu_inc/dec operation instead of __get_cpu_var |
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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.
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(); } -- 1.7.10.4
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