From: Chris Wilson <chris@chris-wilson.co.uk>
To: Andi Shyti <andi@etezian.org>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 1/5] drm/i915/selftests: Skip unstable timing measurements
Date: Fri, 08 Jan 2021 13:54:35 +0000 [thread overview]
Message-ID: <161011407580.28368.6023725628158257155@build.alporthouse.com> (raw)
In-Reply-To: <X/hjekGVV5F+sokg@jack.zhora.eu>
Quoting Andi Shyti (2021-01-08 13:51:54)
> Hi Chris,
>
> > > > diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
> > > > index 75839db63bea..59c58a276677 100644
> > > > --- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
> > > > +++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
> > > > @@ -852,6 +852,9 @@ static int _perf_memcpy(struct intel_memory_region *src_mr,
> > > > }
> > > >
> > > > sort(t, ARRAY_SIZE(t), sizeof(*t), wrap_ktime_compare, NULL);
> > > > + if (!t[0])
> > > > + continue;
> > > > +
> > >
> > > are you assuming here that if t[0] is '0', also the rest of 't'
> > > is '0'?
> >
> > It's sorted into ascending order with ktime_t... Hmm, s64 not u64 as I
> > presumed. So better to check <= 0.
>
> by division by 0 I guess you mean here:
>
> div64_u64(mul_u32_u32(4 * size,
> 1000 * 1000 * 1000),
> t[1] + 2 * t[2] + t[3]) >> 20);
>
> why are you testing t[0]? Did I miss anything else?
Since t[0] is the most negative value, if it is <= 0 that implies at
least one of the measurements was bad. If any are bad, all are bad by
association. I considered checking t[4] to make sure that at least the
best was good enough, but paranoia won.
-Chris
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next prev parent reply other threads:[~2021-01-08 13:54 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-07 22:17 [Intel-gfx] [PATCH 1/5] drm/i915/selftests: Skip unstable timing measurements Chris Wilson
2021-01-07 22:17 ` [Intel-gfx] [PATCH 2/5] drm/i915/gt: Restore ce->signal flush before releasing virtual engine Chris Wilson
2021-01-08 15:18 ` Andi Shyti
2021-01-08 15:24 ` Chris Wilson
2021-01-08 15:54 ` Andi Shyti
2021-01-07 22:17 ` [Intel-gfx] [PATCH 3/5] drm/i915/gt: Only retire on the last breadcrumb if the last request Chris Wilson
2021-01-08 15:55 ` Andi Shyti
2021-01-07 22:17 ` [Intel-gfx] [PATCH 4/5] drm/i915/gt: Only disable preemption on gen8 render engines Chris Wilson
2021-01-08 15:24 ` Andi Shyti
2021-01-07 22:17 ` [Intel-gfx] [PATCH 5/5] drm/i915/gt: Disable arbitration on no-preempt requests Chris Wilson
2021-01-08 15:27 ` Andi Shyti
2021-01-07 23:07 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [1/5] drm/i915/selftests: Skip unstable timing measurements Patchwork
2021-01-07 23:09 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2021-01-07 23:38 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
2021-01-08 0:16 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [1/5] drm/i915/selftests: Skip unstable timing measurements (rev2) Patchwork
2021-01-08 0:18 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2021-01-08 0:45 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-01-08 2:59 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
2021-01-08 12:26 ` [Intel-gfx] [PATCH 1/5] drm/i915/selftests: Skip unstable timing measurements Andi Shyti
2021-01-08 13:26 ` Chris Wilson
2021-01-08 13:51 ` Andi Shyti
2021-01-08 13:54 ` Chris Wilson [this message]
2021-01-08 15:04 ` Andi Shyti
2021-01-08 13:28 ` [Intel-gfx] [PATCH] " Chris Wilson
2021-01-08 15:14 ` Chris Wilson
2021-01-08 15:25 ` Andi Shyti
2021-01-08 18:14 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with drm/i915/selftests: Skip unstable timing measurements (rev4) Patchwork
2021-01-08 18:16 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2021-01-08 18:45 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
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