On Mon, 2024-06-03 at 10:28 +0200, Karolina Stolarek wrote:
> > > > > diff --git a/drivers/gpu/drm/ttm/tests/ttm_kunit_helpers.c
> > > > > b/drivers/gpu/drm/ttm/tests/ttm_kunit_helpers.c
> > > > > index 2f590bae53f8..2a2585b37118 100644
> > > > > --- a/drivers/gpu/drm/ttm/tests/ttm_kunit_helpers.c
> > > > > +++ b/drivers/gpu/drm/ttm/tests/ttm_kunit_helpers.c
> > > > > @@ -27,8 +27,42 @@ static int mock_move(struct
> > > > > ttm_buffer_object
> > > > > *bo,
> > > > > bool evict,
> > > > > struct ttm_resource *new_mem,
> > > > > struct ttm_place *hop)
> > > > > {
> (...)
> > > > > +
> > > > > + if (ret)
> > > > > + return ret;
> > > > > +
> > > > > + ttm_resource_free(bo, &bo->resource);
> > > > > + ttm_bo_assign_mem(bo, new_mem);
> > > > > + return 0;
> > > > > + }
> > > > > +
> > > > > + return ttm_bo_move_memcpy(bo, ctx, new_mem);
> > > >
> > > > Do we hit this move_memcpy()? Since the mock manager doesn't
> > > > actually
> > > > reserve any memory to manager, I'd expect this to run into
> > > > problems?
> > >
> > > We do. The mock manager has use_tt=true, so on move, we'd use
> > > ttm_kmap_iter_tt_init() for src and dest and copy the pages. I'm
> > > not
> > > sure if that's the right approach, but it enables me to test if
> > > ttm_operation_ctx's bytes_moved is correctly updated.
> >
> > Ah, ok. It's probably not a common use-case since with both src and
> > dst
> > having use_tt, IIRC ttm should keep the pages and their content
> > mostly
> > intact across a move. So you would memcpy the source on itself?
> >
> > But it would give some coverage of the copy code though.
>
> I dug around and it looks like, in the current scenario,
> ttm_bo_move_memcpy() is just ttm_bo_move_sync_cleanup()
> (ttm_resource_free + ttm_bo_assign_mem). That means I should revisit
> the
> definitions of move and mock manager... I'll try to simplify them.
>
> Do I understand correctly that we'd prefer to have a mock manager
> with
> user_tt=false?
Yes, but then you need to allocate a chunk of contigous memory for the
mock manager to manage. And instead of using drm_buddy you'd have to
use drm_mm to manage it, since the ttm_kmap_iter default iterators can
only handle either
a) Contigous memory regions as returned from the drm_mm manager.
b) Fragmented memory regions as returned from the drm_buddy manager,
but in that case, they currently only handle pci io memory.
So I'd suggest to go with the current code and mark as a TODO: to
implement a) above.
/Thomas
>
> All the best,
> Karolina
>
> >
> > /Thomas
