23cd1e030e
Also add to the CI a problem matcher to better report issues Signed-off-by: Brennan Ashton <bashton@brennanashton.com>
97 lines
3.6 KiB
ReStructuredText
97 lines
3.6 KiB
ReStructuredText
====================
|
|
Task Trace Internals
|
|
====================
|
|
|
|
Overview
|
|
========
|
|
|
|
.. image:: image/task-trace-internal.png
|
|
|
|
The Task Trace is constructed by the following functions.
|
|
|
|
NuttX kernel events collection
|
|
------------------------------
|
|
|
|
The kernel events are collected by ``sched_note_*()`` API calls embedded in NuttX kernel.
|
|
|
|
- For task switch events
|
|
|
|
- ``sched_note_start()``
|
|
- ``sched_note_stop()``
|
|
- ``sched_note_suspend()``
|
|
- ``sched_note_resume()``
|
|
|
|
- For system call events
|
|
|
|
- ``sched_note_syscall_enter()``
|
|
- ``sched_note_syscall_leave()``
|
|
|
|
- For interrupt event
|
|
|
|
- ``sched_note_irqhandler()``
|
|
|
|
Filter logic (``nuttx/sched/sched_note.c``)
|
|
-------------------------------------------
|
|
|
|
- The ``sched_note_*()`` APIs are implemented here.
|
|
- Filter the notes and pass them to noteram driver by ``sched_note_add()`` API.
|
|
|
|
Noteram device driver (``nuttx/drivers/note/noteram_driver.c``)
|
|
---------------------------------------------------------------
|
|
|
|
- Accumurate incoming note records into the buffer.
|
|
- Read the note records from the buffer by user requests.
|
|
- The notes are recorded in the binary format of ``struct note_*_s``.
|
|
- The detail function is described in :doc:`../components/drivers/character/note`.
|
|
|
|
Notectl device driver (``nuttx/drivers/note/notectl_driver.c``)
|
|
---------------------------------------------------------------
|
|
|
|
- ``/dev/notectl`` device driver.
|
|
- Control the filter logic in ``sched_note.c`` by calling note filter APIs.
|
|
- The detail function is described in :doc:`../components/drivers/character/note`.
|
|
|
|
"``trace``" Built-In Application (``apps/system/trace/trace.c``)
|
|
----------------------------------------------------------------
|
|
|
|
- ``trace`` Built-In Application to control the trace function interactively.
|
|
- Read binary note records from ``/dev/note`` and convert into the ftrace text format which is acceptable by `"Trace Compass" <https://www.eclipse.org/tracecompass/>`_.
|
|
- The command syntax is described in :doc:`tasktraceuser`.
|
|
|
|
Getting the system call events
|
|
==============================
|
|
|
|
To get the system call events, two different methods are used for FLAT build and PROTECTED/KERNEL build.
|
|
|
|
FLAT build
|
|
----------
|
|
|
|
In FLAT build, a system call is just a function call into the NuttX kernel.
|
|
|
|
.. image:: image/syscall-flat-before.png
|
|
|
|
To get the system call events, `wrapper function option <https://sourceware.org/binutils/docs/ld/Options.html#index-_002d_002dwrap_003dsymbol>`_ of the GNU Linker is used.
|
|
|
|
The mksyscall tool is fixed to generate the system call wrapper which call system call enter/leave hook.
|
|
The wrapper supersedes the system call function call of the NuttX binary by passing ``--wrap`` linker option to the build system.
|
|
The wrapper calls the system call hooks before and after calling the real system call function.
|
|
|
|
.. image:: image/syscall-flat-after.png
|
|
|
|
PROTECTED/KERNEL build
|
|
----------------------
|
|
|
|
Different to FLAT build, in PROTECTED and KERNEL build, a system call is issued by an user space is handled as the following steps.
|
|
|
|
#. System call issued by an application code is handled by the system call proxy (automatically generated by mksyscall).
|
|
#. System call proxy issues the supervisor call instruction to enter into the kernel space.
|
|
#. System call handler in the kernel space calls the system call stub (automatically generated by mksyscall).
|
|
#. System call stub calls the API implementation in the NuttX kernel.
|
|
|
|
.. image:: image/syscall-protected-before.png
|
|
|
|
To get the system call events, the mksyscall tool is fixed to generate the system call wrapper which supersedes the system call function call in the system call stub.
|
|
|
|
.. image:: image/syscall-protected-after.png
|
|
|