ftrace: use cpu clock again

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 1 insertions, 53 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3dc6eac85b11..d74c039305ad 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -42,61 +42,9 @@ ns2usecs(cycle_t nsec)
         return nsec;
 }
 
-static const int time_sync_freq_max = 128;
-static const cycle_t time_sync_thresh = 100000;
-
-static DEFINE_PER_CPU(cycle_t, time_offset);
-static DEFINE_PER_CPU(cycle_t, prev_cpu_time);
-static DEFINE_PER_CPU(int, time_sync_count);
-static DEFINE_PER_CPU(int, time_sync_freq);
-
-/*
- * Global lock which we take every now and then to synchronize
- * the CPUs time. This method is not warp-safe, but it's good
- * enough to synchronize slowly diverging time sources and thus
- * it's good enough for tracing:
- */
-static DEFINE_SPINLOCK(time_sync_lock);
-static cycle_t prev_global_time;
-
-static notrace cycle_t __ftrace_now_sync(cycles_t time, int cpu)
-{
-        unsigned long flags;
-
-        spin_lock_irqsave(&time_sync_lock, flags);
-
-        /*
-         * Update the synchronization frequency:
-         */
-        if (per_cpu(time_sync_freq, cpu) < time_sync_freq_max)
-                per_cpu(time_sync_freq, cpu) *= 2;
-        per_cpu(time_sync_count, cpu) = per_cpu(time_sync_freq, cpu);
-
-        if (time < prev_global_time) {
-                per_cpu(time_offset, cpu) += prev_global_time - time;
-                time = prev_global_time;
-        } else {
-                prev_global_time = time;
-        }
-
-        spin_unlock_irqrestore(&time_sync_lock, flags);
-
-        return time;
-}
-
 notrace cycle_t ftrace_now(int cpu)
 {
-        cycle_t prev_cpu_time, time, delta_time;
-
-        prev_cpu_time = per_cpu(prev_cpu_time, cpu);
-        time = sched_clock() + per_cpu(time_offset, cpu);
-        delta_time = time-prev_cpu_time;
-
-        if (unlikely(delta_time > time_sync_thresh ||
-                                --per_cpu(time_sync_count, cpu) <= 0))
-                time = __ftrace_now_sync(time, cpu);
-
-        return time;
+        return cpu_clock(cpu);
 }
 
 static struct trace_array       global_trace;