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SubjectRe: [RFC PATCH 6/7] drm/ttm: Introduce a huge page aligning TTM range manager.
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I don't see the advantage over just increasing the alignment 
requirements in the driver side?

That would be a one liner if I'm not completely mistaken.

Regards,
Christian.

Am 27.11.19 um 09:31 schrieb Thomas Hellström (VMware):
> From: Thomas Hellstrom <thellstrom@vmware.com>
>
> Using huge page-table entries require that the start of a buffer object
> is huge page size aligned. So introduce a ttm_bo_man_get_node_huge()
> function that attempts to accomplish this for allocations that are larger
> than the huge page size, and provide a new range-manager instance that
> uses that function.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> Cc: Ralph Campbell <rcampbell@nvidia.com>
> Cc: "Jérôme Glisse" <jglisse@redhat.com>
> Cc: "Christian König" <christian.koenig@amd.com>
> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
> ---
> drivers/gpu/drm/ttm/ttm_bo_manager.c | 92 ++++++++++++++++++++++++++++
> include/drm/ttm/ttm_bo_driver.h | 1 +
> 2 files changed, 93 insertions(+)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_manager.c b/drivers/gpu/drm/ttm/ttm_bo_manager.c
> index 18d3debcc949..26aa1a2ae7f1 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_manager.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_manager.c
> @@ -89,6 +89,89 @@ static int ttm_bo_man_get_node(struct ttm_mem_type_manager *man,
> return 0;
> }
>
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +static int ttm_bo_insert_aligned(struct drm_mm *mm, struct drm_mm_node *node,
> + unsigned long align_pages,
> + const struct ttm_place *place,
> + struct ttm_mem_reg *mem,
> + unsigned long lpfn,
> + enum drm_mm_insert_mode mode)
> +{
> + if (align_pages >= mem->page_alignment &&
> + (!mem->page_alignment || align_pages % mem->page_alignment == 0)) {
> + return drm_mm_insert_node_in_range(mm, node,
> + mem->num_pages,
> + align_pages, 0,
> + place->fpfn, lpfn, mode);
> + }
> +
> + return -ENOSPC;
> +}
> +
> +static int ttm_bo_man_get_node_huge(struct ttm_mem_type_manager *man,
> + struct ttm_buffer_object *bo,
> + const struct ttm_place *place,
> + struct ttm_mem_reg *mem)
> +{
> + struct ttm_range_manager *rman = (struct ttm_range_manager *) man->priv;
> + struct drm_mm *mm = &rman->mm;
> + struct drm_mm_node *node;
> + unsigned long align_pages;
> + unsigned long lpfn;
> + enum drm_mm_insert_mode mode = DRM_MM_INSERT_BEST;
> + int ret;
> +
> + node = kzalloc(sizeof(*node), GFP_KERNEL);
> + if (!node)
> + return -ENOMEM;
> +
> + lpfn = place->lpfn;
> + if (!lpfn)
> + lpfn = man->size;
> +
> + mode = DRM_MM_INSERT_BEST;
> + if (place->flags & TTM_PL_FLAG_TOPDOWN)
> + mode = DRM_MM_INSERT_HIGH;
> +
> + spin_lock(&rman->lock);
> + if (IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)) {
> + align_pages = (HPAGE_PUD_SIZE >> PAGE_SHIFT);
> + if (mem->num_pages >= align_pages) {
> + ret = ttm_bo_insert_aligned(mm, node, align_pages,
> + place, mem, lpfn, mode);
> + if (!ret)
> + goto found_unlock;
> + }
> + }
> +
> + align_pages = (HPAGE_PMD_SIZE >> PAGE_SHIFT);
> + if (mem->num_pages >= align_pages) {
> + ret = ttm_bo_insert_aligned(mm, node, align_pages, place, mem,
> + lpfn, mode);
> + if (!ret)
> + goto found_unlock;
> + }
> +
> + ret = drm_mm_insert_node_in_range(mm, node, mem->num_pages,
> + mem->page_alignment, 0,
> + place->fpfn, lpfn, mode);
> +found_unlock:
> + spin_unlock(&rman->lock);
> +
> + if (unlikely(ret)) {
> + kfree(node);
> + } else {
> + mem->mm_node = node;
> + mem->start = node->start;
> + }
> +
> + return 0;
> +}
> +#else
> +#define ttm_bo_man_get_node_huge ttm_bo_man_get_node
> +#endif
> +
> +
> static void ttm_bo_man_put_node(struct ttm_mem_type_manager *man,
> struct ttm_mem_reg *mem)
> {
> @@ -154,3 +237,12 @@ const struct ttm_mem_type_manager_func ttm_bo_manager_func = {
> .debug = ttm_bo_man_debug
> };
> EXPORT_SYMBOL(ttm_bo_manager_func);
> +
> +const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func = {
> + .init = ttm_bo_man_init,
> + .takedown = ttm_bo_man_takedown,
> + .get_node = ttm_bo_man_get_node_huge,
> + .put_node = ttm_bo_man_put_node,
> + .debug = ttm_bo_man_debug
> +};
> +EXPORT_SYMBOL(ttm_bo_manager_huge_func);
> diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
> index cac7a8a0825a..868bd0d4be6a 100644
> --- a/include/drm/ttm/ttm_bo_driver.h
> +++ b/include/drm/ttm/ttm_bo_driver.h
> @@ -888,5 +888,6 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo);
> pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp);
>
> extern const struct ttm_mem_type_manager_func ttm_bo_manager_func;
> +extern const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func;
>
> #endif

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