Currently, we are using an alignment of 128 kB to insert a node, which ends up wasting memory as we perform plenty of small BOs allocations (<= 4 kB). We require that allocations are aligned to 128Kb so for any allocation smaller than that, we are wasting the difference.
This implies that we cannot effectively use the whole 4 GB address space available for the GPU in the RPi 4. Currently, we can allocate up to 32000 BOs of 4 kB (~140 MB) and 3000 BOs of 400 kB (~1,3 GB). This can be quite limiting for applications that have a high memory requirement, such as vkoverhead [1]. By reducing the page alignment to 4 kB, we can allocate up to 1000000 BOs of 4 kB (~4 GB) and 10000 BOs of 400 kB (~4 GB). Moreover, by performing benchmarks, we were able to attest that reducing the page alignment to 4 kB can provide a general performance improvement in OpenGL applications (e.g. glmark2). Therefore, this patch reduces the alignment of the node allocation to 4 kB, which will allow RPi users to explore the whole 4GB virtual address space provided by the hardware. Also, this patch allow users to fully run vkoverhead in the RPi 4/5, solving the issue reported in [1]. [1] https://github.com/zmike/vkoverhead/issues/14 Signed-off-by: Maíra Canal <mca...@igalia.com> --- drivers/gpu/drm/v3d/v3d_bo.c | 2 +- drivers/gpu/drm/v3d/v3d_drv.h | 2 -- 2 files changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/gpu/drm/v3d/v3d_bo.c b/drivers/gpu/drm/v3d/v3d_bo.c index a07ede668cc1..79e31c5299b1 100644 --- a/drivers/gpu/drm/v3d/v3d_bo.c +++ b/drivers/gpu/drm/v3d/v3d_bo.c @@ -110,7 +110,7 @@ v3d_bo_create_finish(struct drm_gem_object *obj) */ ret = drm_mm_insert_node_generic(&v3d->mm, &bo->node, obj->size >> V3D_MMU_PAGE_SHIFT, - GMP_GRANULARITY >> V3D_MMU_PAGE_SHIFT, 0, 0); + SZ_4K >> V3D_MMU_PAGE_SHIFT, 0, 0); spin_unlock(&v3d->mm_lock); if (ret) return ret; diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h index d2ce8222771a..17236ee23490 100644 --- a/drivers/gpu/drm/v3d/v3d_drv.h +++ b/drivers/gpu/drm/v3d/v3d_drv.h @@ -17,8 +17,6 @@ struct clk; struct platform_device; struct reset_control; -#define GMP_GRANULARITY (128 * 1024) - #define V3D_MMU_PAGE_SHIFT 12 #define V3D_MAX_QUEUES (V3D_CPU + 1) -- 2.44.0
