user/sven/linux.git/kernel/trace/trace_output.c, branch v4.9.243

tracing: Add NMI tracing in hwlat detector

2016-09-02T16:47:55Z

As NMIs can also cause latency when interrupts are disabled, the hwlat detectory has no way to know if the latency it detects is from an NMI or an SMI or some other hardware glitch. As ftrace_nmi_enter/exit() funtions are no longer used (except for sh, which isn't supported anymore), I converted those to "arch_ftrace_nmi_enter/exit" and use ftrace_nmi_enter/exit() to check if hwlat detector is tracing or not, and if so, it calls into the hwlat utility. Since the hwlat detector only has a single kthread that is spinning with interrupts disabled, it marks what CPU it is on, and if the NMI callback happens on that CPU, it records the time spent in that NMI. This is added to the output that is generated by the hwlat detector as: #3 inner/outer(us): 9/9 ts:1470836488.206734548 #4 inner/outer(us): 0/8 ts:1470836497.140808588 #5 inner/outer(us): 0/6 ts:1470836499.140825168 nmi-total:5 nmi-count:1 #6 inner/outer(us): 9/9 ts:1470836501.140841748 All time is still tracked in microseconds. The NMI information is only shown when an NMI occurred during the sample. Signed-off-by: Steven Rostedt

tracing: Added hardware latency tracer

2016-09-02T16:47:51Z

The hardware latency tracer has been in the PREEMPT_RT patch for some time. It is used to detect possible SMIs or any other hardware interruptions that the kernel is unaware of. Note, NMIs may also be detected, but that may be good to note as well. The logic is pretty simple. It simply creates a thread that spins on a single CPU for a specified amount of time (width) within a periodic window (window). These numbers may be adjusted by their cooresponding names in /sys/kernel/tracing/hwlat_detector/ The defaults are window = 1000000 us (1 second) width = 500000 us (1/2 second) The loop consists of: t1 = trace_clock_local(); t2 = trace_clock_local(); Where trace_clock_local() is a variant of sched_clock(). The difference of t2 - t1 is recorded as the "inner" timestamp and also the timestamp t1 - prev_t2 is recorded as the "outer" timestamp. If either of these differences are greater than the time denoted in /sys/kernel/tracing/tracing_thresh then it records the event. When this tracer is started, and tracing_thresh is zero, it changes to the default threshold of 10 us. The hwlat tracer in the PREEMPT_RT patch was originally written by Jon Masters. I have modified it quite a bit and turned it into a tracer. Based-on-code-by: Jon Masters Signed-off-by: Steven Rostedt

tracing: Record and show NMI state

2016-03-22T22:04:10Z

The latency tracer format has a nice column to indicate IRQ state, but this is not able to tell us about NMI state. When tracing perf interrupt handlers (which often run in NMI context) it is very useful to see how the events nest. Link: http://lkml.kernel.org/r/20160318153022.105068893@infradead.org Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Steven Rostedt

tracing: Move trace_flags from global to a trace_array field

2015-09-30T19:22:55Z

In preparation to make trace options per instance, the global trace_flags needs to be moved from being a global variable to a field within the trace instance trace_array structure. There's still more work to do, as there's some functions that use trace_flags without passing in a way to get to the current_trace array. For those, the global_trace is used directly (from trace.c). This includes setting and clearing the trace_flags. This means that when a new instance is created, it just gets the trace_flags of the global_trace and will not be able to modify them. Depending on the functions that have access to the trace_array, the flags of an instance may not affect parts of its trace, where the global_trace is used. These will be fixed in future changes. Signed-off-by: Steven Rostedt

tracing: Turn seq_print_user_ip() into a static function

2015-09-28T14:16:12Z

seq_print_user_ip() is used in only one location in one file. Turn it into a static function. We could inject its code into the caller, but that would make the code a bit too complex. Keep the code separate. Signed-off-by: Steven Rostedt

tracing: Inject seq_print_userip_objs() into its only user

2015-09-28T14:11:44Z

seq_print_userip_objs() is used only in one location, in one file. Instead of having it as an external function, go one further than making it static, but inject is code into its only user. It doesn't make the calling function much more complex. Signed-off-by: Steven Rostedt

tracing: Introduce two additional marks for delay

2015-07-21T02:30:52Z

A fine granulity support for delay would be very useful when profiling VM logics, such as page allocation including page reclaim and memory compaction with function graph. Thus, this patch adds two additional marks with two changes. - An equal sign in mark selection function is removed to align code behavior with comments and documentation. - The function graph example related to delay in ftrace.txt is updated to cover all supported marks. Link: http://lkml.kernel.org/r/1436626300-1679-3-git-send-email-jungseoklee85@gmail.com Cc: Byungchul Park Signed-off-by: Jungseok Lee Signed-off-by: Steven Rostedt

tracing: Rename ftrace_event_name() to trace_event_name()

2015-05-13T18:20:14Z

The name "ftrace" really refers to the function hook infrastructure. It is not about the trace_events. ftrace_event_name() returns the name of an event tracepoint, has nothing to do with function tracing. Rename it to trace_event_name(). Signed-off-by: Steven Rostedt

tracing: Rename FTRACE_MAX_EVENT to TRACE_EVENT_TYPE_MAX

2015-05-13T18:06:42Z

The name "ftrace" really refers to the function hook infrastructure. It is not about the trace_events. Rename the max trace_event type size to something more descriptive and appropriate. Signed-off-by: Steven Rostedt

tracing: Rename ftrace_output functions to trace_output

2015-05-13T18:06:41Z

The name "ftrace" really refers to the function hook infrastructure. It is not about the trace_events. The ftrace_output_*() and ftrace_raw_output_*() functions represent the trace_event code. Rename them to just trace_output or trace_raw_output. Signed-off-by: Steven Rostedt