Re: [PATCH 1/3] drm/ttm: Issue direct reclaim at beneficial_order

[Matthew Brost <matthew.brost@intel.com>]

On Tue, Apr 21, 2026 at 08:11:17AM +0200, Christian König wrote:
> On 4/21/26 03:26, Matthew Brost wrote:
> > Triggering kswap at an order higher than beneficial_order makes little
> > sense, as the driver has already indicated the optimal order at which
> > reclaim is effective. Similarly, issuing direct reclaim or triggering
> > kswap at a lower order than beneficial_order is ineffective, since the
> > driver does not benefit from reclaiming lower-order pages.
> > 
> > As a result, direct reclaim should only be issued with __GFP_NORETRY at
> > exactly beneficial_order, or as a fallback, direct reclaim without
> > __GFP_NORETRY at order 0 when failure is not an option.
> > 
> > Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > Cc: Carlos Santa <carlos.santa@intel.com>
> > Cc: Christian Koenig <christian.koenig@amd.com>
> > Cc: Huang Rui <ray.huang@amd.com>
> > Cc: Matthew Auld <matthew.auld@intel.com>
> > Cc: Matthew Brost <matthew.brost@intel.com>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Maxime Ripard <mripard@kernel.org>
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: David Airlie <airlied@gmail.com>
> > Cc: Simona Vetter <simona@ffwll.ch>
> > CC: dri-devel@lists.freedesktop.org
> > Cc: Daniel Colascione <dancol@dancol.org>
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> 
> Reviewed-by: Christian König <christian.koenig@amd.com>
> 

Thanks! I'm going to merge this patch to independently to drm-misc-next
unless you object - the Xe side heuristics of the shrinker will take a
bit longer to land on an agreed upon design.

Matt

> > ---
> >  drivers/gpu/drm/ttm/ttm_pool.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
> > index 26a3689e5fd9..8425dbcc6c68 100644
> > --- a/drivers/gpu/drm/ttm/ttm_pool.c
> > +++ b/drivers/gpu/drm/ttm/ttm_pool.c
> > @@ -165,8 +165,8 @@ static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t gfp_flags,
> >  	 * Do not add latency to the allocation path for allocations orders
> >  	 * device tolds us do not bring them additional performance gains.
> >  	 */
> > -	if (beneficial_order && order > beneficial_order)
> > -		gfp_flags &= ~__GFP_DIRECT_RECLAIM;
> > +	if (order && beneficial_order && order != beneficial_order)
> > +		gfp_flags &= ~__GFP_RECLAIM;
> >  
> >  	if (!ttm_pool_uses_dma_alloc(pool)) {
> >  		p = alloc_pages_node(pool->nid, gfp_flags, order);
>