[PATCH 2/3] drm/amdgpu: Set GTT size equal to TTM mem limit

[Chen, Guchun]

Looks you can drop macro 'AMDGPU_DEFAULT_GTT_SIZE_MB' as well.

Regards,
Guchun

> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of
> Mukul Joshi
> Sent: Wednesday, April 26, 2023 9:53 AM
> To: amd-gfx at lists.freedesktop.org; dri-devel at lists.freedesktop.org
> Cc: Joshi, Mukul <Mukul.Joshi at amd.com>; Kuehling, Felix
> <Felix.Kuehling at amd.com>; Koenig, Christian <Christian.Koenig at amd.com>
> Subject: [PATCH 2/3] drm/amdgpu: Set GTT size equal to TTM mem limit
> 
> Use the helper function in TTM to get TTM mem limit and set GTT size to be
> equal to TTL mem limit.
> 
> Signed-off-by: Mukul Joshi <mukul.joshi at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 25 ++++++-------------------
>  1 file changed, 6 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index ce34b73d05bc..ac220c779fc8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1807,26 +1807,13 @@ int amdgpu_ttm_init(struct amdgpu_device
> *adev)
>  	DRM_INFO("amdgpu: %uM of VRAM memory ready\n",
>  		 (unsigned) (adev->gmc.real_vram_size / (1024 * 1024)));
> 
> -	/* Compute GTT size, either based on 1/2 the size of RAM size
> -	 * or whatever the user passed on module init */
> -	if (amdgpu_gtt_size == -1) {
> -		struct sysinfo si;
> -
> -		si_meminfo(&si);
> -		/* Certain GL unit tests for large textures can cause problems
> -		 * with the OOM killer since there is no way to link this
> memory
> -		 * to a process.  This was originally mitigated (but not
> necessarily
> -		 * eliminated) by limiting the GTT size.  The problem is this
> limit
> -		 * is often too low for many modern games so just make the
> limit 1/2
> -		 * of system memory which aligns with TTM. The OOM
> accounting needs
> -		 * to be addressed, but we shouldn't prevent common 3D
> applications
> -		 * from being usable just to potentially mitigate that corner
> case.
> -		 */
> -		gtt_size = max((AMDGPU_DEFAULT_GTT_SIZE_MB << 20),
> -			       (u64)si.totalram * si.mem_unit / 2);
> -	} else {
> +	/* Compute GTT size, either based on TTM limit
> +	 * or whatever the user passed on module init.
> +	 */
> +	if (amdgpu_gtt_size == -1)
> +		gtt_size = ttm_tt_pages_limit() << PAGE_SHIFT;
> +	else
>  		gtt_size = (uint64_t)amdgpu_gtt_size << 20;
> -	}
> 
>  	/* Initialize GTT memory pool */
>  	r = amdgpu_gtt_mgr_init(adev, gtt_size);
> --
> 2.35.1