From 197165d44925bd0fa892990851dee4d312a44b39 Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Fri, 24 Apr 2015 14:24:44 +0530 Subject: powerpc/ftrace: add powerpc timebase as a trace clock source Add a new powerpc-specific trace clock using the timebase register, similar to x86-tsc. This gives us - a fast, monotonic, hardware clock source for trace entries, and - a clock that can be used to correlate events across cpus as well as across hypervisor and guests. Signed-off-by: Naveen N. Rao Acked-by: Steven Rostedt Signed-off-by: Michael Ellerman --- Documentation/trace/ftrace.txt | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'Documentation/trace') diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 7ddb1e319f84..87bb4aa6a6b9 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -346,6 +346,11 @@ of ftrace. Here is a list of some of the key files: x86-tsc: Architectures may define their own clocks. For example, x86 uses its own TSC cycle clock here. + ppc-tb: This uses the powerpc timebase register value. + This is in sync across CPUs and can also be used + to correlate events across hypervisor/guest if + tb_offset is known. + To set a clock, simply echo the clock name into this file. echo global > trace_clock -- cgit v1.2.3-59-g8ed1b