[Intel-gfx] [PATCH] drm/i915/gt: limit lmem allocation size to succeed on SmallBars

[Andi Shyti]

Hi Andrzej,

On Thu, Jun 01, 2023 at 04:44:50PM +0200, Andrzej Hajda wrote:
> In case system is short on mappable memory (256MB on SmallBar) allocation
> of two 1GB buffers will fail.
> 
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8300
> Signed-off-by: Andrzej Hajda <andrzej.hajda at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/selftest_tlb.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/selftest_tlb.c b/drivers/gpu/drm/i915/gt/selftest_tlb.c
> index 4493c8518e91b2..3bd6b540257b46 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_tlb.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_tlb.c
> @@ -190,11 +190,18 @@ pte_tlbinv(struct intel_context *ce,
>  
>  static struct drm_i915_gem_object *create_lmem(struct intel_gt *gt)
>  {
> +	struct intel_memory_region *mr = gt->i915->mm.regions[INTEL_REGION_LMEM_0];
> +	resource_size_t size = SZ_1G;
> +
>  	/*
>  	 * Allocation of largest possible page size allows to test all types
> -	 * of pages.
> +	 * of pages. To succeed with both allocations, especially in case of Small
> +	 * BAR, try to allocate no more than quarter of mappable memory.
>  	 */
> -	return i915_gem_object_create_lmem(gt->i915, SZ_1G, I915_BO_ALLOC_CONTIGUOUS);
> +	if (mr && size > mr->io_size / 4)
> +		size = mr->io_size / 4;
> +
> +	return i915_gem_object_create_lmem(gt->i915, size, I915_BO_ALLOC_CONTIGUOUS);

makes sense to me.

Reviewed-by: Andi Shyti <andi.shyti at linux.intel.com> 

Thanks,
Andi