On Mon, 13 Sep 2021, Nicolas Saenz Julienne wrote:
> Some architectures have special purpose registers to query the system
> counter's frequency. Let's use that when available.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzju@xxxxxxxxxx>
> --
>
> Changes since v1:
> - Use cleaner method to have generic and arch functions to measure
> couter's freq
>
> src/oslat/oslat.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/src/oslat/oslat.c b/src/oslat/oslat.c
> index c90ec1a..5fce223 100644
> --- a/src/oslat/oslat.c
> +++ b/src/oslat/oslat.c
> @@ -74,6 +74,16 @@ static inline void frc(uint64_t *pval)
> # elif defined(__aarch64__)
> # define relax() __asm__ __volatile("yield" : : : "memory")
>
> +#define arch_measure_counter_mhz
> +static unsigned int measure_counter_mhz(void)
> +{
> + unsigned int val;
> +
> + __asm__ __volatile__("mrs %0, cntfrq_el0" : "=r" (val));
> +
> + return val / 1e6;
> +}
> +
> static inline void frc(uint64_t *pval)
> {
> /*
> @@ -241,6 +251,7 @@ static int move_to_core(int core_i)
> return sched_setaffinity(0, sizeof(cpus), &cpus);
> }
>
> +#ifndef arch_measure_counter_mhz
> static cycles_t __measure_counter_hz(void)
> {
> struct timeval tvs, tve;
> @@ -273,6 +284,7 @@ static unsigned int measure_counter_mhz(void)
>
> return (unsigned int) (m / 1000000);
> }
> +#endif
>
> static void thread_init(struct thread *t)
> {
> --
> 2.31.1
>
>
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: John Kacur <jkacur@xxxxxxxxxx>
