zephyr

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Gerard Marull-Paretas 6810a53297 twister: s/riscv(32\|64)/riscv Only riscv is supported now, any 32/64-bit requirements need to use CONFIG_64BIT now. Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>		2024-02-26 12:49:06 +01:00
..
src
CMakeLists.txt
prj.conf
README.rst
sample.yaml	twister: s/riscv(32\|64)/riscv	2024-02-26 12:49:06 +01:00

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