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Message-ID: <50A9C1BD.1060308@gmail.com> Date: Mon, 19 Nov 2012 13:21:01 +0800 From: Shan Wei <shanwei88@...il.com> To: rostedt@...dmis.org, fweisbec@...il.com, mingo@...hat.com, Kernel-Maillist <linux-kernel@...r.kernel.org>, Christoph Lameter <cl@...ux.com> Subject: [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var From: Shan Wei <davidshan@...cent.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@...cent.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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