[PATCH 08/16] tracing: have event_trace_printk use static tracer

Steven Rostedt
2009-03-13T02:42:38Z

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From: Steven Rostedt <srostedt@redhat.com>

Impact: speed up on event tracing

The event_trace_printk is currently a wrapper function that calls
trace_vprintk. Because it uses a variable for the fmt it misses out
on the optimization of using the binary printk.

This patch makes event_trace_printk into a macro wrapper to use the
fmt as the same as the trace_printks.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
kernel/trace/trace.h | 17 +++++++++++++++++
kernel/trace/trace_events.c | 10 ----------
2 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index cede1ab..35cfa7b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -773,4 +773,21 @@ void event_trace_printk(unsigned long ip, const char *fmt, ...);
extern struct ftrace_event_call __start_ftrace_events[];
extern struct ftrace_event_call __stop_ftrace_events[];

+extern const char *__start___trace_bprintk_fmt[];
+extern const char *__stop___trace_bprintk_fmt[];
+
+#define event_trace_printk(ip, fmt, args...) \
+do { \
+ __trace_printk_check_format(fmt, ##args); \
+ tracing_record_cmdline(current); \
+ if (__builtin_constant_p(fmt)) { \
+ static const char *trace_printk_fmt \
+ __attribute__((section("__trace_printk_fmt"))) = \
+ __builtin_constant_p(fmt) ? fmt : NULL; \
+ \
+ __trace_bprintk(ip, trace_printk_fmt, ##args); \
+ } else \
+ __trace_printk(ip, fmt, ##args); \
+} while (0)
+
#endif /* _LINUX_KERNEL_TRACE_H */
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index ca624df..238ea95 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -24,16 +24,6 @@ static DEFINE_MUTEX(event_mutex);
(unsigned long)event < (unsigned long)__stop_ftrace_events; \
event++)

-void event_trace_printk(unsigned long ip, const char *fmt, ...)
-{
- va_list ap;
-
- va_start(ap, fmt);
- tracing_record_cmdline(current);
- trace_vprintk(ip, task_curr_ret_stack(current), fmt, ap);
- va_end(ap);
-}
-
static void ftrace_clear_events(void)
{
struct ftrace_event_call *call = (void *)__start_ftrace_events;
--
1.6.1.3

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