[Mesa-dev] [PATCH] gallium/u_threaded: replace pipe_resource_reference with atomic_inc

[Michel Dänzer]

On 13/06/17 01:31 AM, Marek Olšák wrote:
> From: Marek Olšák <marek.olsak at amd.com>
> 
> ---
>  src/gallium/auxiliary/util/u_threaded_context.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/src/gallium/auxiliary/util/u_threaded_context.c b/src/gallium/auxiliary/util/u_threaded_context.c
> index 3038fc6..a97f016 100644
> --- a/src/gallium/auxiliary/util/u_threaded_context.c
> +++ b/src/gallium/auxiliary/util/u_threaded_context.c
> @@ -195,22 +195,27 @@ _tc_sync(struct threaded_context *tc, const char *info, const char *func)
>  
>     tc_debug_check(tc);
>  }
>  
>  #define tc_sync(tc) _tc_sync(tc, "", __func__)
>  #define tc_sync_msg(tc, info) _tc_sync(tc, info, __func__)
>  
>  static void
>  tc_set_resource_reference(struct pipe_resource **dst, struct pipe_resource *src)
>  {
> -   *dst = NULL;
> -   pipe_resource_reference(dst, src);
> +   /* Unexpectedly, pipe_resource_reference is a bottleneck here, taking 3.7%
> +    * of CPU time in a state-heavy microbenchmark. The problem here is that
> +    * pipe_resource_reference isn't inlined here.
> +    */
> +   *dst = src;
> +   if (src)
> +      p_atomic_inc(&src->reference.count);
>  }

That's pretty ugly. Does the attached patch help as well? It allows
pipe_resource_reference to be inlined again, and has a pretty dramatic
effect on the size of the generated code for me:

   text	   data	    bss	    dec	    hex	filename
  42586	    512	      0	  43098	   a85a	u_threaded_context.o
  35282	    512	      0	  35794	   8bd2	u_threaded_context.o.patched

   text	   data	    bss	    dec	    hex	filename
10434626	 271176	2062272	12768074	 c2d34a	/tmp/radeonsi_dri.so
10001218	 271176	2062272	12334666	 bc364a	/tmp/radeonsi_dri.so.patched


It might also help for other pipe_resource_reference callers.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer
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