[PATCH v6 12/12] drm/xe: Increase the XE_PL_TT watermark

[Souza, Jose]

On Wed, 2024-07-03 at 17:38 +0200, Thomas Hellström wrote:
> The XE_PL_TT watermark was set to 50% of system memory.
> The idea behind that was unclear since the net effect is that
> TT memory will be evicted to TTM_PL_SYSTEM memory if that
> watermark is exceeded, requiring PPGTT rebinds and dma
> remapping. But there is no similar watermark for TTM_PL_SYSTEM
> memory.
> 
> The TTM functionality that tries to swap out system memory to
> shmem objects if a 50% limit of total system memory is reached
> is orthogonal to this, and with the shrinker added, it's no
> longer in effect.
> 
> Replace the 50% TTM_PL_TT limit with a 100% limit, in effect
> allowing all graphics memory to be bound to the device unless it
> has been swapped out by the shrinker.

Sorry if I missed some patch changing it but I did not found in this series anything changing the 50% limit in ttm_global_init().
When I debugged some Vulkan tests allocate a lot of memory, the reason that KMD was not allocating memory wash this ttm_global limit that is shared
with all devices using TTM.

> 
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> ---
>  drivers/gpu/drm/xe/xe_ttm_sys_mgr.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_ttm_sys_mgr.c b/drivers/gpu/drm/xe/xe_ttm_sys_mgr.c
> index 9844a8edbfe1..d38b91872da3 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_sys_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_sys_mgr.c
> @@ -108,9 +108,8 @@ int xe_ttm_sys_mgr_init(struct xe_device *xe)
>  	u64 gtt_size;
>  
>  	si_meminfo(&si);
> +	/* Potentially restrict amount of TT memory here. */
>  	gtt_size = (u64)si.totalram * si.mem_unit;
> -	/* TTM limits allocation of all TTM devices by 50% of system memory */
> -	gtt_size /= 2;
>  
>  	man->use_tt = true;
>  	man->func = &xe_ttm_sys_mgr_func;