[Intel-gfx] [PATCH i-g-t] tests/gem_mmap_gtt(huge_bo): Use pread more to verify domain transfer.

[Chris Wilson]

On Wed, May 06, 2015 at 04:22:23PM +0300, Joonas Lahtinen wrote:
> On ke, 2015-05-06 at 14:15 +0100, Chris Wilson wrote:
> > On Wed, May 06, 2015 at 03:31:10PM +0300, Joonas Lahtinen wrote:
> > > 
> > > Use pread right after moving out of CPU domain to verify all
> > > writes flushed correctly.
> > 
> > Wrong test, see gem_pread. Adding extra work may have the unintended
> > side-effects of masking bugs. If you want to mix access modes, call it a
> > new test, and that is handled by gem_concurrent_blt (which once again is
> > difting far beyond the original name).
> 
> This is specifically for the huge_bo test, where the kernel side
> handling is expected to be different than for the others, so it stresses
> the code path related to huge BO's.

See gem_pread. Your huge_bo merely classifies as big...
 
> Better wording to add to it:
> "Make sure that the introduction of the partial GTT mappings which are
> expected to be in use when mapping an object bigger than the aperture
> size do not corrupt the contents of the backing storage"

But mixing pread and set-domain has strictly undefined semantics in
terms of what domain we expect the buffer to be in afterwards i.e. to be
correct you would have to call set-domain again after pread.

And you really should add huge_bo testing to gem_concurrent_blt.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre