From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jan Stancek <jstancek@redhat.com>
Date: Sat, 7 Sep 2019 05:31:40 -0400 (EDT)
Subject: [LTP] [PATCH v2] fzsync: drop pair->spins_avg.avg check
In-Reply-To: <87sgpbkjst.fsf@rpws.prws.suse.cz>
References: <2ded10ab8d989ba7ee0cc1e9f1ac28acdf14c947.1567606698.git.jstancek@redhat.com>
 <750a63b18523493412cb53e748b519b7dfbd70b0.1567685224.git.jstancek@redhat.com>
 <87sgpbkjst.fsf@rpws.prws.suse.cz>
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----- Original Message -----
> 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

Pushed.