79e6b0e0f6
As of today <zephyr/zephyr.h> is 100% equivalent to <zephyr/kernel.h>. This patch proposes to then include <zephyr/kernel.h> instead of <zephyr/zephyr.h> since it is more clear that you are including the Kernel APIs and (probably) nothing else. <zephyr/zephyr.h> sounds like a catch-all header that may be confusing. Most applications need to include a bunch of other things to compile, e.g. driver headers or subsystem headers like BT, logging, etc. The idea of a catch-all header in Zephyr is probably not feasible anyway. Reason is that Zephyr is not a library, like it could be for example `libpython`. Zephyr provides many utilities nowadays: a kernel, drivers, subsystems, etc and things will likely grow. A catch-all header would be massive, difficult to keep up-to-date. It is also likely that an application will only build a small subset. Note that subsystem-level headers may use a catch-all approach to make things easier, though. NOTE: This patch is **NOT** removing the header, just removing its usage in-tree. I'd advocate for its deprecation (add a #warning on it), but I understand many people will have concerns. Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no> |
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| src | ||
| CMakeLists.txt | ||
| README.rst | ||
| prj.conf | ||
| sample.yaml | ||
README.rst
.. _syscall_perf:
Syscall performances
====================
The goal of this sample application is to measure the performance loss when a
user thread has to go through a system call compared to a supervisor thread that
calls the function directly.
Overview
********
This application creates a supervisor and a user thread.
Then both threads call k_current_get() which returns a reference to the
current thread. The user thread has to go through a system call.
Both threads are showing the number of core clock cycles and the number of
instructions executed while calling k_current_get().
Sample Output
*************
.. code-block:: console
User thread: 18012 cycles 748 instructions
Supervisor thread: 7 cycles 4 instructions
User thread: 20136 cycles 748 instructions
Supervisor thread: 7 cycles 4 instructions
User thread: 18014 cycles 748 instructions
Supervisor thread: 7 cycles 4 instructions