diff options
Diffstat (limited to 'Documentation/trace/ftrace.rst')
| -rw-r--r-- | Documentation/trace/ftrace.rst | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index e45f0786f3f9..6b80ac4bbaae 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -224,6 +224,8 @@ of ftrace. Here is a list of some of the key files: has a side effect of enabling or disabling specific functions to be traced. Echoing names of functions into this file will limit the trace to only those functions. + This influences the tracers "function" and "function_graph" + and thus also function profiling (see "function_profile_enabled"). The functions listed in "available_filter_functions" are what can be written into this file. @@ -265,6 +267,8 @@ of ftrace. Here is a list of some of the key files: Functions listed in this file will cause the function graph tracer to only trace these functions and the functions that they call. (See the section "dynamic ftrace" for more details). + Note, set_ftrace_filter and set_ftrace_notrace still affects + what functions are being traced. set_graph_notrace: @@ -277,7 +281,8 @@ of ftrace. Here is a list of some of the key files: This lists the functions that ftrace has processed and can trace. These are the function names that you can pass to - "set_ftrace_filter" or "set_ftrace_notrace". + "set_ftrace_filter", "set_ftrace_notrace", + "set_graph_function", or "set_graph_notrace". (See the section "dynamic ftrace" below for more details.) dyn_ftrace_total_info: @@ -461,9 +466,17 @@ of ftrace. Here is a list of some of the key files: and ticks at the same rate as the hardware clocksource. boot: - Same as mono. Used to be a separate clock which accounted - for the time spent in suspend while CLOCK_MONOTONIC did - not. + This is the boot clock (CLOCK_BOOTTIME) and is based on the + fast monotonic clock, but also accounts for time spent in + suspend. Since the clock access is designed for use in + tracing in the suspend path, some side effects are possible + if clock is accessed after the suspend time is accounted before + the fast mono clock is updated. In this case, the clock update + appears to happen slightly sooner than it normally would have. + Also on 32-bit systems, it's possible that the 64-bit boot offset + sees a partial update. These effects are rare and post + processing should be able to handle them. See comments in the + ktime_get_boot_fast_ns() function for more information. To set a clock, simply echo the clock name into this file:: |