David Komel 211e5b73c0 kernel: k_busy_wait() should return immediately on zero timeout ... When CONFIG_ARCH_HAS_CUSTOM_BUSY_WAIT is not defined, cycles_to_wait is calculated using a division operation. This calculation could take a significant amount of time (a few microseconds on some architectures, depending on the system clock). In the special case of zero usec_to_wait, the function should return immediately rather than spend time on calculations. For example, in spi driver (spi_context.h, _spi_context_cs_control()), k_busy_wait() can be called with zero delay. This can increase spi transaction time significantly. Another improvement, is moving the start_cycles initialization before cycles_to_wait calculation, so the time it takes to calculate cycles_to_wait will be taken into account. Signed-off-by: David Komel <a8961713@gmail.com>		2020-10-14 14:52:06 -04:00
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include
atomic_c.c
cache_handlers.c
CMakeLists.txt
compiler_stack_protect.c
device.c
errno.c
fatal.c
futex.c
idle.c
init.c
Kconfig
kheap.c
mailbox.c
mem_domain.c
mem_slab.c
mempool_sys.c
mempool.c
mmu.c
msg_q.c
mutex.c
pipes.c
poll.c
queue.c
sched.c
sem.c
smp.c
stack.c
system_work_q.c
thread_abort.c
thread.c
timeout.c
timer.c
userspace_handler.c
userspace.c
version.c
work_q.c