[igt-dev] [RFT v4 4/6] igt/i915: Require GTT mapping to be available when needed.

[Chris Wilson]

Quoting Antonio Argenziano (2019-04-05 19:00:57)
> 
> 
> On 27/03/19 14:24, Chris Wilson wrote:
> > Quoting Antonio Argenziano (2019-03-27 21:05:52)
> >>
> >>
> >> On 25/03/19 16:36, Chris Wilson wrote:
> >>> Quoting Antonio Argenziano (2019-03-25 23:20:41)
> >>>> diff --git a/lib/igt_dummyload.c b/lib/igt_dummyload.c
> >>>> index 47f6b92b..2e4c0335 100644
> >>>> --- a/lib/igt_dummyload.c
> >>>> +++ b/lib/igt_dummyload.c
> >>>> @@ -117,9 +117,11 @@ emit_recursive_batch(igt_spin_t *spin,
> >>>>           obj[BATCH].handle = gem_create(fd, BATCH_SIZE);
> >>>>           batch = __gem_mmap__wc(fd, obj[BATCH].handle,
> >>>>                                  0, BATCH_SIZE, PROT_WRITE);
> >>>> -       if (!batch)
> >>>> +       if (!batch) {
> >>>> +               gem_require_mmap_gtt(fd);
> >>>>                   batch = gem_mmap__gtt(fd, obj[BATCH].handle,
> >>>>                                           BATCH_SIZE, PROT_WRITE);
> >>>
> >>> batch = __gem_mmap__gtt();
> >>> igt_require(batch) ?
> >>>
> >>> Possibly not as informative as gem_require_mmap_gtt() So ~o~
> >>>
> >>>> diff --git a/tests/i915/gem_concurrent_all.c b/tests/i915/gem_concurrent_all.c
> >>>> index f719b0a1..e4fc1426 100644
> >>>> --- a/tests/i915/gem_concurrent_all.c
> >>>> +++ b/tests/i915/gem_concurrent_all.c
> >>>> @@ -1422,6 +1422,7 @@ static void cpu_require(void)
> >>>>    
> >>>>    static void gtt_require(void)
> >>>>    {
> >>>> +       gem_require_mmap_gtt(fd);
> >>>>    }
> >>>
> >>> Needs the combinatorial explosion to exercise accessing via mmap-offset.
> >>> If you only update one stress test, update this one.
> >>
> >> Don't we get the mmap-offset coverage by default in the wc test cases or
> >> do you mean to use the mmap_offset IOCTL to mmap GTT?
> > 
> > No, I forgot that the library was going to automatic replacement of
> > gem_mmap__wc and friends. Must update this stress test, it is useful
> > simply because it runs forever and ends up being quite quite brutal.
> > (Even the trivial starting tests are too often enough to reveal issues.)
> 
> AFAICT it already iterates over all mappings which include WC and CPU. 
> We only skip gtt when gtt mapping is not available. What needs updating?

I just meant that this is one of those "must haves". It's simply too
useful for finding GEM instabilities (mostly because it runs for such a
long time ;).
-Chris