Commit 60303ed3 authored Oct 11, 2012 by David Sharp Committed by Steven Rostedt Nov 02, 2012

tracing: Reset ring buffer when changing trace_clocks

Because the "tsc" clock isn't in nanoseconds, the ring buffer must be
reset when changing clocks so that incomparable timestamps don't end up
in the same trace.

Tested: Confirmed switching clocks resets the trace buffer.

Google-Bug-Id: 6980623
Link: http://lkml.kernel.org/r/1349998076-15495-3-git-send-email-dhsharp@google.com



Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: David Sharp <dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

parent 60efc15a

kernel/trace/trace.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -4073,6 +4073,14 @@ static ssize_t tracing_clock_write(struct file filp, const char __user ubuf,
		if (max_tr.buffer)
		ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);

		/*
		* New clock may not be consistent with the previous clock.
		* Reset the buffer so that it doesn't have incomparable timestamps.
		*/
		tracing_reset_online_cpus(&global_trace);
		if (max_tr.buffer)
		tracing_reset_online_cpus(&max_tr);

		mutex_unlock(&trace_types_lock);

		*fpos += cnt;