From 9826b2733a4399149072058a11f611357479229d Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Date: Thu, 28 May 2015 17:36:45 -0400
Subject: [PATCH] ring-buffer: Move the adding of the extended timestamp out of
line
Requiring a extended time stamp is an uncommon occurrence, and it is
best to do it out of line when needed.
Add a noinline function that handles the extended timestamp and
have it called with an unlikely to completely move it out of the
fast path.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/ring_buffer.c | 41 +++++++++++++++++++++++---------------
1 file changed, 25 insertions(+), 16 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index ba8f25ffcf6f..a78d4ee4bc58 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2396,6 +2396,29 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
return NULL;
}
+#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
+static inline bool sched_clock_stable(void)
+{
+ return true;
+}
+#endif
+
+static noinline void
+rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
+ struct rb_event_info *info)
+{
+ WARN_ONCE(info->delta > (1ULL << 59),
+ KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s",
+ (unsigned long long)info->delta,
+ (unsigned long long)info->ts,
+ (unsigned long long)cpu_buffer->write_stamp,
+ sched_clock_stable() ? "" :
+ "If you just came from a suspend/resume,\n"
+ "please switch to the trace global clock:\n"
+ " echo global > /sys/kernel/debug/tracing/trace_clock\n");
+ info->add_timestamp = 1;
+}
+
static struct ring_buffer_event *
__rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
struct rb_event_info *info)
@@ -2582,22 +2605,8 @@ rb_reserve_next_event(struct ring_buffer *buffer,
/* Did the write stamp get updated already? */
if (likely(info.ts >= cpu_buffer->write_stamp)) {
info.delta = diff;
- if (unlikely(test_time_stamp(info.delta))) {
- int local_clock_stable = 1;
-#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
- local_clock_stable = sched_clock_stable();
-#endif
- WARN_ONCE(info.delta > (1ULL << 59),
- KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s",
- (unsigned long long)info.delta,
- (unsigned long long)info.ts,
- (unsigned long long)cpu_buffer->write_stamp,
- local_clock_stable ? "" :
- "If you just came from a suspend/resume,\n"
- "please switch to the trace global clock:\n"
- " echo global > /sys/kernel/debug/tracing/trace_clock\n");
- info.add_timestamp = 1;
- }
+ if (unlikely(test_time_stamp(info.delta)))
+ rb_handle_timestamp(cpu_buffer, &info);
}
event = __rb_reserve_next(cpu_buffer, &info);
--
2.30.9