Re: [PATCH i-g-t] tests/gem_exec_fence: test that in-fence is not overwritten

[Chris Wilson <chris@chris-wilson.co.uk>]

Quoting Chris Wilson (2018-02-14 19:29:29)
> Quoting Daniele Ceraolo Spurio (2018-02-14 19:18:26)
> > When an out-fence is returned we expect that the in-fence is not
> > overwritten. Add a test to check for that.
> > 
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> > ---
> >  tests/gem_exec_fence.c | 39 +++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 39 insertions(+)
> > 
> > diff --git a/tests/gem_exec_fence.c b/tests/gem_exec_fence.c
> > index bd7b1263..f7478c55 100644
> > --- a/tests/gem_exec_fence.c
> > +++ b/tests/gem_exec_fence.c
> > @@ -586,6 +586,42 @@ static void test_parallel(int fd, unsigned int master)
> >         gem_close(fd, handle[0]);
> >  }
> >  
> > +/* check that a fence in doesn't get clobbered when a fence out is returned */
> > +static void test_keep_fence_in(int fd, unsigned int engine)
> > +{
> > +       struct drm_i915_gem_execbuffer2 execbuf;
> > +       struct drm_i915_gem_exec_object2 obj;
> > +       const uint32_t bbe = MI_BATCH_BUFFER_END;
> > +       int fence;
> > +
> > +       memset(&obj, 0, sizeof(obj));
> > +       memset(&execbuf, 0, sizeof(execbuf));
> > +
> > +       obj.handle = gem_create(fd, 4096);
> > +       gem_write(fd, obj.handle, 0, &bbe, sizeof(bbe));
> > +
> > +       execbuf.buffers_ptr = to_user_pointer(&obj);
> > +       execbuf.buffer_count = 1;
> > +       execbuf.flags = engine | LOCAL_EXEC_FENCE_OUT;
> > +
> > +       gem_execbuf_wr(fd, &execbuf);
> > +       fence = execbuf.rsvd2 >> 32;
> > +
> > +       gem_close(fd, obj.handle);
> > +       obj.handle = gem_create(fd, 4096);
> > +       gem_write(fd, obj.handle, 0, &bbe, sizeof(bbe));
> 
> You don't need to recreate the batch here; just reusing the same handle
> will do (and avoid the extra complication).
> 
> > +
> > +       execbuf.flags |= LOCAL_EXEC_FENCE_IN;
> > +       execbuf.rsvd2 = fence;
> > +
> > +       gem_execbuf_wr(fd, &execbuf);
> > +       igt_assert_eq(fence, execbuf.rsvd2 & 0xFFFFFFFF);
> 
> This would be a good one to throw to the interruptible wolves.

Of course to actually interrupt it, we need to hit a wait. Hmm. I'd use
a variant of the measure ring size approach, scrap the second test, and
then repeatedly re-submit until it hit an EINTR. (Obviously requires a
timer, and updating/checking the fences on each pass).
-Chris
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