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authorIngo Molnar <mingo@elte.hu>2009-03-09 10:11:36 +0100
committerIngo Molnar <mingo@elte.hu>2009-03-09 10:11:36 +0100
commit7bffc23e56e92c14b787bf4d95249a32085bfed5 (patch)
tree9c1bbea2f258c82b5a9ff5e30db3a8f0c9cc3faa
parent8a20d84d09ab5d121f989cd99e4fc5f4b49f98ba (diff)
downloadlinaro-lsk-7bffc23e56e92c14b787bf4d95249a32085bfed5.tar.gz
tracing: optimize trace_printk()
Impact: micro-optimization trace_printk() does this unconditionally: trace_printk_fmt = fmt; Where trace_printk_fmt is an entry into a global array. This is very SMP-unfriendly. So only write it once per bootup. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <1236356510-8381-5-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/kernel.h10
1 files changed, 8 insertions, 2 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 4e726b9a71e..7742798c920 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -454,7 +454,10 @@ do { \
do { \
static const char *trace_printk_fmt \
__attribute__((section("__trace_printk_fmt"))); \
- trace_printk_fmt = fmt; \
+ \
+ if (!trace_printk_fmt) \
+ trace_printk_fmt = fmt; \
+ \
__trace_printk_check_format(fmt, ##args); \
__trace_printk(_THIS_IP_, trace_printk_fmt, ##args); \
} while (0)
@@ -467,7 +470,10 @@ __trace_printk(unsigned long ip, const char *fmt, ...)
do { \
static const char *trace_printk_fmt \
__attribute__((section("__trace_printk_fmt"))); \
- trace_printk_fmt = fmt; \
+ \
+ if (!trace_printk_fmt) \
+ trace_printk_fmt = fmt; \
+ \
__ftrace_vprintk(_THIS_IP_, trace_printk_fmt, vargs); \
} while (0)