NAME¶
dispatch_benchmark —
Measures block execution time
SYNOPSIS¶
#include
<dispatch/dispatch.h>
uint64_t
dispatch_benchmark(
size_t
count,
void (^block)(void));
uint64_t
dispatch_benchmark_f(
size_t
count,
void *context,
void (*function)(void *));
DESCRIPTION¶
The
dispatch_benchmark() function executes
the given
block multiple times according to
the
count variable and then returns the
average number of nanoseconds per execution. This function is for debugging
and performance analysis work. For the best results, pass a high count value
to
dispatch_benchmark(). When benchmarking
concurrent code, please compare the serial version of the code against the
concurrent version, and compare the concurrent version on different classes of
hardware. Please look for inflection points with various data sets and keep
the following facts in mind:
- Code bound by computational bandwidth may be inferred by proportional
changes in performance as concurrency is increased.
- Code bound by memory bandwidth may be inferred by negligible changes in
performance as concurrency is increased.
- Code bound by critical sections may be inferred by retrograde changes in
performance as concurrency is increased.
- Intentional: locks, mutexes, and condition variables.
- Accidental: unrelated and frequently modified data on the same
cache-line.
RETURN VALUE¶
The
dispatch_benchmark() function returns the
average number of nanoseconds the given block takes to execute.
SEE ALSO¶
dispatch(3)
