[Mesa-dev] [PATCH 1/2] r600: Fix possible endless loop in compute_memory_pool allocations.

[Jan Vesely]

On Thu, 2014-06-19 at 17:27 +0200, Bruno Jimenez wrote:
> Hi,
> 
> Thanks for catching this bug!
> 
> Reviewed-by: Bruno Jiménez <brunojimen at gmail.com>
> 
> Also, could you please send me a copy of the tests?

This got triggered by one of the gegl test. You'll need the attached
patches to run gegl git[0] on mesa/clover/r600. you 'll need babl git[1]
too. Let me know if I can help with setting it up.
Sry, I don't have any smaller reproducer.

Jan

[0] git://git.gnome.org/gegl
[1] git://git.gnome.org/babl

> 
> On Thu, 2014-06-19 at 10:21 -0400, Jan Vesely wrote:
> > The important part is the change of the condition to <= 0. Otherwise the loop
> > gets stuck never actually growing the pool.
> > 
> > The change in the aux-need calculation guarantees max 2 iterations, and
> > avoids wasting memory in case a smaller item can't fit into a relatively larger
> > pool.
> > 
> > Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
> > CC: Bruno Jimenez <brunojimen at gmail.com>
> > ---
> > 
> > This fixes hang in gegl colors.xml test
> > 
> >  src/gallium/drivers/r600/compute_memory_pool.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> > 
> > diff --git a/src/gallium/drivers/r600/compute_memory_pool.c b/src/gallium/drivers/r600/compute_memory_pool.c
> > index ec8c470..0b6d2da6 100644
> > --- a/src/gallium/drivers/r600/compute_memory_pool.c
> > +++ b/src/gallium/drivers/r600/compute_memory_pool.c
> > @@ -320,8 +320,11 @@ int compute_memory_finalize_pending(struct compute_memory_pool* pool,
> >  			int64_t need = item->size_in_dw+2048 -
> >  						(pool->size_in_dw - allocated);
> >  
> > -			if (need < 0) {
> > -				need = pool->size_in_dw / 10;
> > +			if (need <= 0) {
> > +				/* There's enough free space, but it's too
> > +				 * fragmented. Assume half of the item can fit
> > +				 * int the last chunk */
> > +				need = (item->size_in_dw / 2) + ITEM_ALIGNMENT;
> >  			}
> >  
> >  			need = align(need, ITEM_ALIGNMENT);
> 
> 

-- 
Jan Vesely <jan.vesely at rutgers.edu>
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