[Mesa-dev] [PATCH 1/2] eg/compute: Use reference counting to handle compute memory pool.

[Jan Vesely]

On Mon, 2018-05-07 at 15:10 +0200, Nicolai Hähnle wrote:
> On 04.05.2018 08:34, Jan Vesely wrote:
> > The original bug/corruption was by util_unreference_framebuffer_state,
> > trying to drop reference on cbuf[0] (global AS for OCL).
> > Adding reference counting to set_rat uncovered problems with acessing the pool->bo.
> > 
> > Also drops leaked memory from 7,4kB to 1,7Kb in single run of conformance_bruteforce trunc -w.
> > 
> > Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
> > ---
> >   src/gallium/drivers/r600/compute_memory_pool.c | 18 ++++++------------
> >   src/gallium/drivers/r600/evergreen_compute.c   |  3 ++-
> >   2 files changed, 8 insertions(+), 13 deletions(-)
> > 
> > diff --git a/src/gallium/drivers/r600/compute_memory_pool.c b/src/gallium/drivers/r600/compute_memory_pool.c
> > index bcda155c71..155fefe54f 100644
> > --- a/src/gallium/drivers/r600/compute_memory_pool.c
> > +++ b/src/gallium/drivers/r600/compute_memory_pool.c
> > @@ -91,10 +91,7 @@ void compute_memory_pool_delete(struct compute_memory_pool* pool)
> >   {
> >   	COMPUTE_DBG(pool->screen, "* compute_memory_pool_delete()\n");
> >   	free(pool->shadow);
> > -	if (pool->bo) {
> > -		pool->screen->b.b.resource_destroy((struct pipe_screen *)
> > -			pool->screen, (struct pipe_resource *)pool->bo);
> > -	}
> > +	pipe_resource_reference(&pool->bo, NULL);
> >   	/* In theory, all of the items were freed in compute_memory_free.
> >   	 * Just delete the list heads
> >   	 */
> > @@ -213,11 +210,9 @@ int compute_memory_grow_defrag_pool(struct compute_memory_pool *pool,
> >   
> >   			compute_memory_defrag(pool, src, dst, pipe);
> >   
> > -			pool->screen->b.b.resource_destroy(
> > -					(struct pipe_screen *)pool->screen,
> > -					src);
> > -
> > -			pool->bo = temp;
> > +			pipe_resource_reference(&pool->bo, dst);
> > +			/* Drop the extra reference from creation */
> > +			pipe_resource_reference(&dst, NULL);
> 
> I believe you could just say
> 
> 		pool->bo = dst;
> 		dst = NULL;
> 
> here, and save two atomic ops.

I think the above would leak old pool->bo (if present). I could do:

	pipe_resource_reference(&pool->bo, NULL);
	pool->bo = temp;

to save one reference op, but I don't think that's critical since we
just copied and defragged all compute buffers. On the other hand it'd
be consistent with the code below if you prefer.

> 
> >   			pool->size_in_dw = new_size_in_dw;
> >   		}
> >   		else {
> > @@ -230,9 +225,8 @@ int compute_memory_grow_defrag_pool(struct compute_memory_pool *pool,
> >   				return -1;
> >   
> >   			pool->size_in_dw = new_size_in_dw;
> > -			pool->screen->b.b.resource_destroy(
> > -					(struct pipe_screen *)pool->screen,
> > -					(struct pipe_resource *)pool->bo);
> > +			pipe_resource_reference(&pool->bo, NULL);
> > +			/* We already have one reference */
> 
> I find this comment confusing.
> 
> The rest looks good to me.

thanks,
Jan

> 
> Cheers,
> Nicolai
> 
> 
> >   			pool->bo = r600_compute_buffer_alloc_vram(pool->screen, pool->size_in_dw * 4);
> >   			compute_memory_shadow(pool, pipe, 0);
> >   
> > diff --git a/src/gallium/drivers/r600/evergreen_compute.c b/src/gallium/drivers/r600/evergreen_compute.c
> > index 6bec1a333f..58626a3114 100644
> > --- a/src/gallium/drivers/r600/evergreen_compute.c
> > +++ b/src/gallium/drivers/r600/evergreen_compute.c
> > @@ -122,7 +122,8 @@ static void evergreen_set_rat(struct r600_pipe_compute *pipe,
> >   	rat_templ.u.tex.first_layer = 0;
> >   	rat_templ.u.tex.last_layer = 0;
> >   
> > -	/* Add the RAT the list of color buffers */
> > +	/* Add the RAT the list of color buffers. Drop the old buffer first. */
> > +	pipe_surface_reference(&pipe->ctx->framebuffer.state.cbufs[id], NULL);
> >   	pipe->ctx->framebuffer.state.cbufs[id] = pipe->ctx->b.b.create_surface(
> >   		(struct pipe_context *)pipe->ctx,
> >   		(struct pipe_resource *)bo, &rat_templ);
> > 
> 
> 
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