[Mesa-dev] [PATCH] llvmpipe: increase fs shader variant instruction cache limit by factor 4

[Brian Paul]

On 10/11/2013 07:11 AM, sroland at vmware.com wrote:
> From: Roland Scheidegger <sroland at vmware.com>
>
> The previous limit of of 128*1024 was reported to cause frequent recompiles
> in some apps due to shader variant thrashing on IRC in some apps leading
> to noticeable lags.
> Note that the LP_MAX_SHADER_VARIANTS limit (1024) was more or less impossible
> to reach, since even simple fragment shaders without texturing (glxgears) used
> more than twice than 128 instructions, hence the instruction limit would have
> always been reached first (excluding things like trivial shaders not writing
> color). Even with the new limit it is VERY likely the instruction limit is hit
> first.
> Should help with such lags due to recompiles (though other shader types have
> their own limits, LP_MAX_SETUP_VARIANTS and DRAW_MAX_SHADER_VARIANTS, in
> particular the latter seems a bit small (128)).
> ---
>   src/gallium/drivers/llvmpipe/lp_limits.h |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/gallium/drivers/llvmpipe/lp_limits.h b/src/gallium/drivers/llvmpipe/lp_limits.h
> index af31b35..8cfab5a 100644
> --- a/src/gallium/drivers/llvmpipe/lp_limits.h
> +++ b/src/gallium/drivers/llvmpipe/lp_limits.h
> @@ -79,7 +79,7 @@
>    * Max number of instructions (for all fragment shaders combined per context)
>    * that will be kept around.
>    */
> -#define LP_MAX_SHADER_INSTRUCTIONS (128*1024)
> +#define LP_MAX_SHADER_INSTRUCTIONS (512*LP_MAX_SHADER_VARIANTS)
>
>   /**
>    * Max number of setup variants that will be kept around.
>

Reviewed-by: Brian Paul <brianp at vmware.com>

Maybe the comment on LP_MAX_SHADER_INSTRUCTIONS should indicate that 
these are LLVM IR instructions, not TGSI instructions, not machine 
instructions.  I had to dig for a while to find that.

-Brian