From 0fd9e0dac9026df09986a4b201518ae015814aef Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 12 May 2008 21:20:48 +0200 Subject: ftrace: use cpu clock again Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- kernel/trace/trace.c | 54 +--------------------------------------------------- 1 file changed, 1 insertion(+), 53 deletions(-) (limited to 'kernel') 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; -- cgit v1.2.3-55-g7522