Re: [PATCH] drm/ttm/pool: Try harder for beneficial orders

[Christian König]

On 6/17/26 04:22, Matthew Brost wrote:
> When a driver specifies a beneficial order, TTM should make a reasonable
> effort to allocate pages at that order.
> 
> Use __GFP_RETRY_MAYFAIL instead of __GFP_NORETRY when allocating at the
> beneficial order. This allows reclaim to try harder before falling back to
> smaller orders, at the cost of longer allocation setup time.
> 
> That tradeoff is acceptable for beneficial-order allocations: higher-order
> backing pages can improve TLB hit rates and reduce the number of TLB
> invalidations needed when moving memory.
> 
> Cc: Christian Koenig <christian.koenig@xxxxxxx>
> Cc: Huang Rui <ray.huang@xxxxxxx>
> Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxxx>
> Cc: Simona Vetter <simona@xxxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>

Reviewed-by: Christian König <christian.koenig@xxxxxxx>

> ---
> 
> Together with other Xe/core shrinker changes currently under development,
> this change significantly improved performance under memory fragmentation
> on PTL. In 3DMark Wild Life Extreme, performance improved by up to 120%
> compared to the baseline fragmented-memory case. GravityMark also showed
> approximately a 20% improvement under similar conditions.
> ---
>  drivers/gpu/drm/ttm/ttm_pool.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
> index 9f0ab99eb289..682ae4f40424 100644
> --- a/drivers/gpu/drm/ttm/ttm_pool.c
> +++ b/drivers/gpu/drm/ttm/ttm_pool.c
> @@ -168,6 +168,11 @@ static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t gfp_flags,
>  	if (order && beneficial_order && order != beneficial_order)
>  		gfp_flags &= ~__GFP_RECLAIM;
>  
> +	if (beneficial_order && order == beneficial_order) {
> +		gfp_flags &= ~__GFP_NORETRY;
> +		gfp_flags |= __GFP_RETRY_MAYFAIL;
> +	}
> +
>  	if (!ttm_pool_uses_dma_alloc(pool)) {
>  		p = alloc_pages_node(pool->nid, gfp_flags, order);
>  		if (p) {