[Intel-xe] [PATCH v2 1/6] drm/xe/bo: Don't limit the TT manager to half of system memory

[Matthew Auld]

On Mon, 19 Jun 2023 at 16:22, Thomas Hellström
<thomas.hellstrom at linux.intel.com> wrote:
>
> TTM enforces this limit a page-allocation time, swapping out TT memory
> if needed.

It seems that limit can be exceeded by just creating one crazy big
object, or having a few as part of the same exec() call. If unable to
lock an object it seems to just skip it (-EBUSY), and if there are no
objects left to iterate over it just carries on with the allocation.
The hard limit in sys_mgr seemed to prevent that. Do we know if this
new behaviour is now expected?

>
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> Reviewed-by: Matthew Brost <matthew.brost at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_ttm_sys_mgr.c | 2 --
>  1 file changed, 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 3e1fa0c832ca..961bbc29dcdf 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_sys_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_sys_mgr.c
> @@ -106,8 +106,6 @@ int xe_ttm_sys_mgr_init(struct xe_device *xe)
>
>         si_meminfo(&si);
>         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;
> --
> 2.40.1
>