From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Christoph Lameter <cl@linux.com>,
Shan Wei <davidshan@tencent.com>
Subject: [PATCH 03/11] tracing: Use __this_cpu_inc/dec operation instead of __get_cpu_var
Date: Sat, 02 Feb 2013 09:18:45 -0500 [thread overview]
Message-ID: <20130202141955.137013185@goodmis.org> (raw)
In-Reply-To: <20130202141842.189550803@goodmis.org>
[-- Attachment #1: Type: text/plain, Size: 1274 bytes --]
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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next prev parent reply other threads:[~2013-02-02 14:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-02 14:18 [PATCH 00/11] [GIT PULL] tracing: Various tracing fixes and enhancements Steven Rostedt
2013-02-02 14:18 ` [PATCH 01/11] tracing: Mark tracing_dentry_percpu() static Steven Rostedt
2013-02-02 14:18 ` [PATCH 02/11] tracing: Remove tracepoint sample code Steven Rostedt
2013-02-02 14:18 ` Steven Rostedt [this message]
2013-02-02 14:18 ` [PATCH 04/11] tracing: Remove second iterator initializer Steven Rostedt
2013-02-02 14:18 ` [PATCH 05/11] tracing/fgraph: Adjust fgraph depth before calling trace return callback Steven Rostedt
2013-02-02 14:18 ` [PATCH 06/11] ring-buffer: Add stats field for amount read from trace ring buffer Steven Rostedt
2013-02-02 14:18 ` [PATCH 07/11] tracing: Use sched_clock_cpu for trace_clock_global Steven Rostedt
2013-02-02 14:18 ` [PATCH 08/11] tracing: Replace static old_tracer check of tracer name Steven Rostedt
2013-02-02 14:18 ` [PATCH 09/11] tracing: Make a snapshot feature available from userspace Steven Rostedt
2013-02-02 14:18 ` [PATCH 10/11] tracing: Add documentation of snapshot utility Steven Rostedt
2013-02-02 14:18 ` [PATCH 11/11] tracing: Init current_trace to nop_trace and remove NULL checks Steven Rostedt
2013-02-03 10:15 ` [PATCH 00/11] [GIT PULL] tracing: Various tracing fixes and enhancements Ingo Molnar
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