ftrace: use cpu clock again

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

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3dc6eac85b1111e971f05405cf25086e0627eb27..d74c039305ad028c39a476278c847137d435a466 100644 (file)
--- 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;