[igt-dev] [RFC PATCH i-g-t v4 1/4] tests/gem_exec_reloc: Don't filter out invalid addresses

[Janusz Krzysztofik]

Hi Chris,

On Friday, November 1, 2019 11:02:45 AM CET Chris Wilson wrote:
> Quoting Janusz Krzysztofik (2019-10-31 15:28:54)
> > Commit a355b2d6eb42 ("igt/gem_exec_reloc: Filter out unavailable
> > addresses for !ppgtt") introduced filtering of addresses possibly
> > occupied by other users of shared GTT.  Unfortunately, that filtering
> > doesn't distinguish between actually occupied addresses and otherwise
> > invalid softpin offsets.  As soon as incorrect GTT alignment is assumed
> > when running on future backends with possibly larger minimum page
> > sizes, a half of calculated offsets to be tested will be incorrectly
> > detected as occupied by other users and silently skipped instead of
> > reported as a problem.  That will significantly distort the intended
> > test pattern.
> > 
> > Filter out failing addresses only if not reported as invalid.
> > 
> > v2: Skip unavailable addresses only when not running on full PPGTT.
> > v3: Replace the not on full PPGTT requirement for skipping with error
> >     code checking.
> > 
> > Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > ---
> >  tests/i915/gem_exec_reloc.c | 12 +++++++++---
> >  1 file changed, 9 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tests/i915/gem_exec_reloc.c b/tests/i915/gem_exec_reloc.c
> > index 5f59fe99..423fed8b 100644
> > --- a/tests/i915/gem_exec_reloc.c
> > +++ b/tests/i915/gem_exec_reloc.c
> > @@ -520,7 +520,7 @@ static void basic_range(int fd, unsigned flags)
> >         uint64_t gtt_size = gem_aperture_size(fd);
> >         const uint32_t bbe = MI_BATCH_BUFFER_END;
> >         igt_spin_t *spin = NULL;
> > -       int count, n;
> > +       int count, n, err;
> >  
> >         igt_require(gem_has_softpin(fd));
> >  
> > @@ -542,8 +542,11 @@ static void basic_range(int fd, unsigned flags)
> >                 gem_write(fd, obj[n].handle, 0, &bbe, sizeof(bbe));
> >                 execbuf.buffers_ptr = to_user_pointer(&obj[n]);
> >                 execbuf.buffer_count = 1;
> > -               if (__gem_execbuf(fd, &execbuf))
> > +               err = __gem_execbuf(fd, &execbuf);
> > +               if (err) {
> 
> > +                       igt_assert(err != -EINVAL);
> 
> I've been thinking about this and I think the right approach is
> 
> /* Iff using a shared GTT, some of it may be reserved */
> igt_assert_eq(err, -ENOSPC);

Thanks for your help, I'll follow your approach.

Shouldn't we also use the trick with invalid reloc here to save request 
emission?

Thanks,
Janusz

> 
> >                         continue;
> > +               }
>