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| author |   Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> | 2015-04-24 14:24:44 +0530 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2015-08-06 16:36:23 +1000 |
| commit | 197165d44925bd0fa892990851dee4d312a44b39 (patch) | |
| tree | 5a3c35443e155b69a87456624ce458ee08a4ba08 /Documentation/trace | |
| parent | powerpc/4xx: Fix return value check in hsta_msi_probe() (diff) | |
| download | linux-dev-197165d44925bd0fa892990851dee4d312a44b39.tar.xz linux-dev-197165d44925bd0fa892990851dee4d312a44b39.zip | |
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 <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/ftrace.txt | 5 |
1 files changed, 5 insertions, 0 deletions
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 |