mirror of
https://github.com/zephyrproject-rtos/zephyr
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407b49b35c
Using find_package to locate Zephyr.
Old behavior was to use $ENV{ZEPHYR_BASE} for inclusion of boiler plate
code.
Whenever an automatic run of CMake happend by the build system / IDE
then it was required that ZEPHYR_BASE was defined.
Using ZEPHYR_BASE only to locate the Zephyr package allows CMake to
cache the base variable and thus allowing subsequent invocation even
if ZEPHYR_BASE is not set in the environment.
It also removes the risk of strange build results if a user switchs
between different Zephyr based project folders and forgetting to reset
ZEPHYR_BASE before running ninja / make.
Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
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| .. | ||
| src | ||
| CMakeLists.txt | ||
| prj.conf | ||
| README.rst | ||
| testcase.yaml | ||
Scheduler Microbenchmark
########################
This is a scheduler microbenchmark, designed to measure minimum
latencies (not scaling performance) of specific low level scheduling
primitives independent of overhead from application or API
abstractions. It works very simply: a main thread creates a "partner"
thread at a higher priority, the partner then sleeps using
_pend_curr_irqlock(). From this initial state:
1. The main thread calls _unpend_first_thread()
2. The main thread calls _ready_thread()
3. The main thread calls k_yield()
(the kernel switches to the partner thread)
4. The partner thread then runs and calls _pend_curr_irqlock() again
(the kernel switches to the main thread)
5. The main thread returns from k_yield()
It then iterates this many times, reporting timestamp latencies
between each numbered step and for the whole cycle, and a running
average for all cycles run.
Note that because this involves no timer interaction (except, on some
architectures, k_cycle_get_32()), it works correctly when run in QEMU
using the -icount argument, which can produce 100% deterministic
behavior (not cycle-exact hardware simulation, but exactly N
instructions per simulated nanosecond). You can enable this using an
environment variable (set at cmake time -- it's not enough to do this
for the subsequent make/ninja invocation, cmake needs to see the
variable itself):
export QEMU_EXTRA_FLAGS="-icount shift=0,align=off,sleep=off"