[LTP] [PATCH v2] fzsync: drop pair->spins_avg.avg check

[Richard Palethorpe]

Hello,

Jan Stancek <jstancek@redhat.com> writes:

> tst_fzsync_pair.spins is increased at least by one on every iteration.
> If during all calibration loops, both A and B manage to complete at
> nearly same time, then spins is increased only by one.
>
> spins_avg starts as 0, and tst_exp_moving_avg() will move it closer
> and closer to 1, but it will never be 1:
>         float f = 0; int i;
>         for (i = 0; i < 4096; i++)
>                 f = tst_exp_moving_avg(0.25f, 1, f);
>         printf("%.15f %d\n", f, f >= 1);
> 	$ 0.999999880790710 0
> which on rare occasion can cause: "Can't calculate random delay".
>
> Drop check and use MAX(pair->spins_avg.avg, 1f) to calculate per_spin_time.
> Also print stats one more time when we hit the warning.
>
> Suggested-by: Richard Palethorpe <rpalethorpe@suse.com>
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> ---
>  include/tst_fuzzy_sync.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/include/tst_fuzzy_sync.h b/include/tst_fuzzy_sync.h
> index de0402c9bbe9..f9a1947c7542 100644
> --- a/include/tst_fuzzy_sync.h
> +++ b/include/tst_fuzzy_sync.h
> @@ -477,8 +477,8 @@ static void tst_fzsync_pair_update(struct tst_fzsync_pair *pair)
>  			tst_res(TINFO, "Minimum sampling period ended");
>  			tst_fzsync_pair_info(pair);
>  		}
> -	} else if (fabsf(pair->diff_ab.avg) >= 1 && pair->spins_avg.avg >= 1) {
> -		per_spin_time = fabsf(pair->diff_ab.avg) / pair->spins_avg.avg;
> +	} else if (fabsf(pair->diff_ab.avg) >= 1) {
> +		per_spin_time = fabsf(pair->diff_ab.avg) / MAX(pair->spins_avg.avg, 1.0f);
>  		time_delay = drand48() * (pair->diff_sa.avg + pair->diff_sb.avg)
>  			- pair->diff_sb.avg;
>  		pair->delay += (int)(time_delay / per_spin_time);
> @@ -495,6 +495,7 @@ static void tst_fzsync_pair_update(struct tst_fzsync_pair *pair)
>  		}
>  	} else if (!pair->sampling) {
>  		tst_res(TWARN, "Can't calculate random delay");
> +		tst_fzsync_pair_info(pair);
>  		pair->sampling = -1;
>  	}

LGTM

-- 
Thank you,
Richard.