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

[Chris Wilson]

Quoting Janusz Krzysztofik (2019-11-04 09:13:28)
> 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?

Could do. If you move the whole probe out of line so it's not easily
confused with the central point of the test, that'll be great.
-Chris