From: "Steven Rostedt (Red Hat)" <[email protected]> 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 <[email protected]> --- 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); -- 2.4.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
