From: Shan Wei <shanwei88@gmail.com>
To: rostedt@goodmis.org, fweisbec@gmail.com, mingo@redhat.com,
Kernel-Maillist <linux-kernel@vger.kernel.org>,
Christoph Lameter <cl@linux.com>
Subject: [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var
Date: Mon, 19 Nov 2012 13:21:01 +0800 [thread overview]
Message-ID: <50A9C1BD.1060308@gmail.com> (raw)
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.
Signed-off-by: Shan Wei <davidshan@tencent.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
next reply other threads:[~2012-11-19 5:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-19 5:21 Shan Wei [this message]
2012-11-19 21:34 ` [PATCH] trace: use __this_cpu_inc/dec operation instead of __get_cpu_var Christoph Lameter
2012-11-30 6:37 ` Shan Wei
2013-02-03 19:18 ` [tip:perf/core] tracing: Use __this_cpu_inc/ dec " tip-bot for Shan Wei
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=50A9C1BD.1060308@gmail.com \
--to=shanwei88@gmail.com \
--cc=cl@linux.com \
--cc=fweisbec@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).