Re: [PATCH linux-evl] evl/latmus: fix spurious overrun on first measurement sample

Tobias Schaffner <[email protected]> writes:

> This delta is not fixed up during the warmup phase leading to spourious
> overruns in the first measurement sample.
>
> Also apply the fixup in the warmup phase.
>
> Signed-off-by: Tobias Schaffner <[email protected]>
> ---
>  drivers/evl/latmus.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/evl/latmus.c b/drivers/evl/latmus.c
> index 9a0295044443..9c581d80db68 100644
> --- a/drivers/evl/latmus.c
> +++ b/drivers/evl/latmus.c
> @@ -166,14 +166,23 @@ static int add_measurement_sample(struct latmus_runner *runner,
>  	ktime_t period = runner->period;
>  	int delta, cell, offset_delta;
>  
> +	delta = (int)ktime_to_ns(ktime_sub(timestamp, state->ideal));
> +	state->ideal = ktime_add(state->ideal, period);
> +
> +	while (delta > 0 &&
> +		(unsigned int)delta > ktime_to_ns(period)) { /* period > 0 */
> +		if (runner->warmup_samples >= runner->warmup_limit)
> +			state->overruns++;
> +		state->ideal = ktime_add(state->ideal, period);
> +		delta -= ktime_to_ns(period);
> +	}
> +
>  	/* Skip samples in warmup time. */
>  	if (runner->warmup_samples < runner->warmup_limit) {
>  		runner->warmup_samples++;
> -		state->ideal = ktime_add(state->ideal, period);
>  		return 0;
>  	}
>  
> -	delta = (int)ktime_to_ns(ktime_sub(timestamp, state->ideal));
>  	offset_delta = delta - state->offset;
>  	if (offset_delta < state->min_lat)
>  		state->min_lat = offset_delta;
> @@ -193,14 +202,6 @@ static int add_measurement_sample(struct latmus_runner *runner,
>  	}
>  
>  	state->sum += offset_delta;
> -	state->ideal = ktime_add(state->ideal, period);
> -
> -	while (delta > 0 &&
> -		(unsigned int)delta > ktime_to_ns(period)) { /* period > 0 */
> -		state->overruns++;
> -		state->ideal = ktime_add(state->ideal, period);
> -		delta -= ktime_to_ns(period);
> -	}
>  
>  	if (++state->cur_samples >= state->max_samples)
>  		send_measurement(runner);

Merged, thanks.

-- 
Philippe.