[Sound-open-firmware] [PATCH] [RFC]platform: calculate the percentage of cpu cycle

[zhigangw]

I use this way to calculate the CPU usage in our firmware.

I am not sure this way is correct or not.

from this way, I found the percentage is very high when I only do the 
playback alone with tdm8 mode.

almost 95% CPU usage.

that is the reason I send this RFC.

please give me the feedback whether this way to calculate the CPU usage 
is correct or not.

thanks

~zhigang


On 2018年06月21日 17:57, Wu Zhigang wrote:
> calculate the percentage of cpu cyle based on
> the CCOUNT register. which can tell the percentage
> of cpu cycle usage.
>
> Signed-off-by: Wu Zhigang <zhigang.wu at linux.intel.com>
> ---
>   src/audio/dai.c | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)
>
> diff --git a/src/audio/dai.c b/src/audio/dai.c
> index 99749d1..7811e38 100644
> --- a/src/audio/dai.c
> +++ b/src/audio/dai.c
> @@ -72,6 +72,21 @@ struct dai_data {
>   	uint64_t wallclock;	/* wall clock at stream start */
>   };
>   
> +/* for apollolake, it is 400MHz per 1s */
> +#define CPU_CYCLE_PER_MS	400000
> +
> +static void calc_mcps(struct pipeline *p)
> +{
> +	uint32_t cpu_cycle = 0;
> +	uint32_t deta = 0;
> +
> +	__asm__ __volatile__ ("rsr %0, CCOUNT" : "=a" (cpu_cycle) : : "memory");
> +	deta = cpu_cycle - p->cpu_cycle;
> +	p->cpu_cycle = cpu_cycle;
> +	deta = (deta * 100) / CPU_CYCLE_PER_MS;
> +	trace_error_value(deta); /* the percentage of the cpu cycle in 1ms */
> +}
> +
>   /* this is called by DMA driver every time descriptor has completed */
>   static void dai_dma_cb(void *data, uint32_t type, struct dma_sg_elem *next)
>   {
> @@ -81,6 +96,8 @@ static void dai_dma_cb(void *data, uint32_t type, struct dma_sg_elem *next)
>   
>   	tracev_dai("irq");
>   
> +	calc_mcps(dev->pipeline);
> +
>   	/* stop dma copy for pause/stop/xrun */
>   	if (dev->state != COMP_STATE_ACTIVE || dd->xrun) {
>