Executing Time Functions¶
The timing functions can be used to obtain execution time of a section of code to aid in analysis and optimization.
Please note that the timing functions may use a different timer than the default kernel timer, where the timer being used is specified by architecture, SoC or board configuration.
Configuration¶
To allow using the timing functions, :kconfig:`CONFIG_TIMING_FUNCTIONS` needs to be enabled.
Usage¶
To gather timing information:
Call
timing_init()to initialize the timer.Call
timing_start()to signal the start of gathering of timing information. This usually starts the timer.Call
timing_counter_get()to mark the start of code execution.Call
timing_counter_get()to mark the end of code execution.Call
timing_cycles_get()to get the number of timer cycles between start and end of code execution.Call
timing_cycles_to_ns()with total number of cycles to convert number of cycles to nanoseconds.Repeat from step 3 to gather timing information for other blocks of code.
Call
timing_stop()to signal the end of gathering of timing information. This usually stops the timer.
Example¶
This shows an example on how to use the timing functions:
#include <timing/timing.h>
void gather_timing(void)
{
timing_t start_time, end_time;
uint64_t total_cycles;
uint64_t total_ns;
timing_init();
timing_start();
start_time = timing_counter_get();
code_execution_to_be_measured();
end_time = timing_counter_get();
total_cycles = timing_cycles_get(&start_time, &end_time);
total_ns = timing_cycles_to_ns(total_cycles);
timing_stop();
}
API documentation¶
-
group
timing_api Timing Measurement APIs.
Functions
-
void
timing_init(void)¶ Initialize the timing subsystem.
Perform the necessary steps to initialize the timing subsystem.
-
void
timing_start(void)¶ Signal the start of the timing information gathering.
Signal to the timing subsystem that timing information will be gathered from this point forward.
-
void
timing_stop(void)¶ Signal the end of the timing information gathering.
Signal to the timing subsystem that timing information is no longer being gathered from this point forward.
-
static inline timing_t
timing_counter_get(void)¶ Return timing counter.
- Returns
Timing counter.
-
static inline uint64_t
timing_cycles_get(volatile timing_t *const start, volatile timing_t *const end)¶ Get number of cycles between
startandend.For some architectures or SoCs, the raw numbers from counter need to be scaled to obtain actual number of cycles.
- Parameters
start – Pointer to counter at start of a measured execution.
end – Pointer to counter at stop of a measured execution.
- Returns
Number of cycles between start and end.
-
static inline uint64_t
timing_freq_get(void)¶ Get frequency of counter used (in Hz).
- Returns
Frequency of counter used for timing in Hz.
-
static inline uint64_t
timing_cycles_to_ns(uint64_t cycles)¶ Convert number of
cyclesinto nanoseconds.- Parameters
cycles – Number of cycles
- Returns
Converted time value
-
static inline uint64_t
timing_cycles_to_ns_avg(uint64_t cycles, uint32_t count)¶ Convert number of
cyclesinto nanoseconds with averaging.- Parameters
cycles – Number of cycles
count – Times of accumulated cycles to average over
- Returns
Converted time value
-
static inline uint32_t
timing_freq_get_mhz(void)¶ Get frequency of counter used (in MHz).
- Returns
Frequency of counter used for timing in MHz.
-
void