Messages in this thread | | | Date | Mon, 23 May 2022 16:52:21 +0100 | Subject | Re: [PATCH 4/4] drm/i915: internal buffers use ttm backend | From | Robert Beckett <> |
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On 11/05/2022 15:14, Thomas Hellström wrote: > On Tue, 2022-05-03 at 19:13 +0000, Robert Beckett wrote: >> refactor internal buffer backend to allocate volatile pages via >> ttm pool allocator >> >> Signed-off-by: Robert Beckett <bob.beckett@collabora.com> >> --- >> drivers/gpu/drm/i915/gem/i915_gem_internal.c | 264 ++++++++--------- >> -- >> drivers/gpu/drm/i915/gem/i915_gem_internal.h | 5 - >> drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 12 +- >> drivers/gpu/drm/i915/gem/i915_gem_ttm.h | 12 +- >> 4 files changed, 125 insertions(+), 168 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_internal.c >> b/drivers/gpu/drm/i915/gem/i915_gem_internal.c >> index c698f95af15f..815ec9466cc0 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_internal.c >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_internal.c >> @@ -4,156 +4,119 @@ >> * Copyright © 2014-2016 Intel Corporation >> */ >> >> -#include <linux/scatterlist.h> >> -#include <linux/slab.h> >> -#include <linux/swiotlb.h> >> - >> +#include <drm/ttm/ttm_bo_driver.h> >> +#include <drm/ttm/ttm_placement.h> >> +#include "drm/ttm/ttm_bo_api.h" >> +#include "gem/i915_gem_internal.h" >> +#include "gem/i915_gem_region.h" >> +#include "gem/i915_gem_ttm.h" >> #include "i915_drv.h" >> -#include "i915_gem.h" >> -#include "i915_gem_internal.h" >> -#include "i915_gem_object.h" >> -#include "i915_scatterlist.h" >> -#include "i915_utils.h" >> - >> -#define QUIET (__GFP_NORETRY | __GFP_NOWARN) >> -#define MAYFAIL (__GFP_RETRY_MAYFAIL | __GFP_NOWARN) >> - >> -static void internal_free_pages(struct sg_table *st) >> -{ >> - struct scatterlist *sg; >> - >> - for (sg = st->sgl; sg; sg = __sg_next(sg)) { >> - if (sg_page(sg)) >> - __free_pages(sg_page(sg), get_order(sg- >>> length)); >> - } >> - >> - sg_free_table(st); >> - kfree(st); >> -} >> >> -static int i915_gem_object_get_pages_internal(struct >> drm_i915_gem_object *obj) >> +static int i915_internal_get_pages(struct drm_i915_gem_object *obj) >> { >> - struct drm_i915_private *i915 = to_i915(obj->base.dev); >> - struct sg_table *st; >> - struct scatterlist *sg; >> - unsigned int sg_page_sizes; >> - unsigned int npages; >> - int max_order; >> - gfp_t gfp; >> - >> - max_order = MAX_ORDER; >> -#ifdef CONFIG_SWIOTLB >> - if (is_swiotlb_active(obj->base.dev->dev)) { >> - unsigned int max_segment; >> - >> - max_segment = swiotlb_max_segment(); >> - if (max_segment) { >> - max_segment = max_t(unsigned int, >> max_segment, >> - PAGE_SIZE) >> PAGE_SHIFT; >> - max_order = min(max_order, >> ilog2(max_segment)); >> - } >> + struct ttm_buffer_object *bo = i915_gem_to_ttm(obj); >> + struct ttm_operation_ctx ctx = { >> + .interruptible = true, >> + .no_wait_gpu = false, >> + }; >> + struct ttm_place place = { >> + .fpfn = 0, >> + .lpfn = 0, >> + .mem_type = I915_PL_SYSTEM, >> + .flags = 0, >> + }; >> + struct ttm_placement placement = { >> + .num_placement = 1, >> + .placement = &place, >> + .num_busy_placement = 0, >> + .busy_placement = NULL, >> + }; >> + int ret; >> + >> + ret = ttm_bo_validate(bo, &placement, &ctx); >> + if (ret) { >> + ret = i915_ttm_err_to_gem(ret); >> + return ret; >> } >> -#endif >> >> - gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE; >> - if (IS_I965GM(i915) || IS_I965G(i915)) { >> - /* 965gm cannot relocate objects above 4GiB. */ >> - gfp &= ~__GFP_HIGHMEM; >> - gfp |= __GFP_DMA32; > > > It looks like we're losing this restriction? > > There is a flag to ttm_device_init() to make TTM only do __GFP_DMA32 > allocations.
agreed. will fix for v2
> >> + if (bo->ttm && !ttm_tt_is_populated(bo->ttm)) { >> + ret = ttm_tt_populate(bo->bdev, bo->ttm, &ctx); >> + if (ret) >> + return ret; >> } >> >> -create_st: >> - st = kmalloc(sizeof(*st), GFP_KERNEL); >> - if (!st) >> - return -ENOMEM; >> + if (!i915_gem_object_has_pages(obj)) { >> + struct i915_refct_sgt *rsgt = >> + i915_ttm_resource_get_st(obj, bo->resource); >> >> - npages = obj->base.size / PAGE_SIZE; >> - if (sg_alloc_table(st, npages, GFP_KERNEL)) { >> - kfree(st); >> - return -ENOMEM; >> - } >> + if (IS_ERR(rsgt)) >> + return PTR_ERR(rsgt); >> >> - sg = st->sgl; >> - st->nents = 0; >> - sg_page_sizes = 0; >> - >> - do { >> - int order = min(fls(npages) - 1, max_order); >> - struct page *page; >> - >> - do { >> - page = alloc_pages(gfp | (order ? QUIET : >> MAYFAIL), >> - order); >> - if (page) >> - break; >> - if (!order--) >> - goto err; >> - >> - /* Limit subsequent allocations as well */ >> - max_order = order; >> - } while (1); >> - >> - sg_set_page(sg, page, PAGE_SIZE << order, 0); >> - sg_page_sizes |= PAGE_SIZE << order; >> - st->nents++; >> - >> - npages -= 1 << order; >> - if (!npages) { >> - sg_mark_end(sg); >> - break; >> - } >> - >> - sg = __sg_next(sg); >> - } while (1); >> - >> - if (i915_gem_gtt_prepare_pages(obj, st)) { >> - /* Failed to dma-map try again with single page sg >> segments */ >> - if (get_order(st->sgl->length)) { >> - internal_free_pages(st); >> - max_order = 0; >> - goto create_st; >> - } >> - goto err; >> + GEM_BUG_ON(obj->mm.rsgt); >> + obj->mm.rsgt = rsgt; >> + __i915_gem_object_set_pages(obj, &rsgt->table, >> + i915_sg_dma_sizes(rsgt- >>> table.sgl)); >> } >> >> - __i915_gem_object_set_pages(obj, st, sg_page_sizes); >> + GEM_BUG_ON(bo->ttm && ((obj->base.size >> PAGE_SHIFT) < bo- >>> ttm->num_pages)); >> + i915_ttm_adjust_lru(obj); >> >> return 0; >> +} >> >> -err: >> - sg_set_page(sg, NULL, 0, 0); >> - sg_mark_end(sg); >> - internal_free_pages(st); >> +static const struct drm_i915_gem_object_ops >> i915_gem_object_internal_ops = { >> + .name = "i915_gem_object_ttm", >> + .flags = I915_GEM_OBJECT_IS_SHRINKABLE, >> >> - return -ENOMEM; >> -} >> + .get_pages = i915_internal_get_pages, >> + .put_pages = i915_ttm_put_pages, >> + .adjust_lru = i915_ttm_adjust_lru, >> + .delayed_free = i915_ttm_delayed_free, >> +}; >> >> -static void i915_gem_object_put_pages_internal(struct >> drm_i915_gem_object *obj, >> - struct sg_table >> *pages) >> +void i915_ttm_internal_bo_destroy(struct ttm_buffer_object *bo) >> { >> - i915_gem_gtt_finish_pages(obj, pages); >> - internal_free_pages(pages); >> + struct drm_i915_gem_object *obj = i915_ttm_to_gem(bo); >> >> - obj->mm.dirty = false; >> + mutex_destroy(&obj->ttm.get_io_page.lock); >> >> - __start_cpu_write(obj); >> -} >> + if (obj->ttm.created) { >> + /* This releases all gem object bindings to the >> backend. */ >> + __i915_gem_free_object(obj); >> >> -static const struct drm_i915_gem_object_ops >> i915_gem_object_internal_ops = { >> - .name = "i915_gem_object_internal", >> - .flags = I915_GEM_OBJECT_IS_SHRINKABLE, >> - .get_pages = i915_gem_object_get_pages_internal, >> - .put_pages = i915_gem_object_put_pages_internal, >> -}; >> + call_rcu(&obj->rcu, __i915_gem_free_object_rcu); >> + } else { >> + __i915_gem_object_fini(obj); >> + } >> +} >> >> +/** >> + * i915_gem_object_create_internal: create an object with volatile >> pages >> + * @i915: the i915 device >> + * @size: the size in bytes of backing storage to allocate for the >> object >> + * >> + * Creates a new object that wraps some internal memory for private >> use. >> + * This object is not backed by swappable storage, and as such its >> contents >> + * are volatile and only valid whilst pinned. If the object is >> reaped by the >> + * shrinker, its pages and data will be discarded. Equally, it is >> not a full >> + * GEM object and so not valid for access from userspace. This makes >> it useful >> + * for hardware interfaces like ringbuffers (which are pinned from >> the time >> + * the request is written to the time the hardware stops accessing >> it), but >> + * not for contexts (which need to be preserved when not active for >> later >> + * reuse). Note that it is not cleared upon allocation. >> + */ >> struct drm_i915_gem_object * >> -__i915_gem_object_create_internal(struct drm_i915_private *i915, >> - const struct >> drm_i915_gem_object_ops *ops, >> - phys_addr_t size) >> +i915_gem_object_create_internal(struct drm_i915_private *i915, >> + phys_addr_t size) >> { >> static struct lock_class_key lock_class; >> struct drm_i915_gem_object *obj; >> unsigned int cache_level; >> + struct ttm_operation_ctx ctx = { >> + .interruptible = true, >> + .no_wait_gpu = false, >> + }; >> + int ret; >> >> GEM_BUG_ON(!size); >> GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE)); >> @@ -166,45 +129,34 @@ __i915_gem_object_create_internal(struct >> drm_i915_private *i915, >> return ERR_PTR(-ENOMEM); >> >> drm_gem_private_object_init(&i915->drm, &obj->base, size); >> - i915_gem_object_init(obj, ops, &lock_class, 0); >> - obj->mem_flags |= I915_BO_FLAG_STRUCT_PAGE; >> + i915_gem_object_init(obj, &i915_gem_object_internal_ops, >> &lock_class, >> + I915_BO_ALLOC_VOLATILE); >> + >> + INIT_LIST_HEAD(&obj->mm.region_link); >> + >> + INIT_RADIX_TREE(&obj->ttm.get_io_page.radix, GFP_KERNEL | >> __GFP_NOWARN); >> + mutex_init(&obj->ttm.get_io_page.lock); >> >> - /* >> - * Mark the object as volatile, such that the pages are >> marked as >> - * dontneed whilst they are still pinned. As soon as they are >> unpinned >> - * they are allowed to be reaped by the shrinker, and the >> caller is >> - * expected to repopulate - the contents of this object are >> only valid >> - * whilst active and pinned. >> - */ >> - i915_gem_object_set_volatile(obj); >> + obj->base.vma_node.driver_private = i915_gem_to_ttm(obj); >> >> + ret = ttm_bo_init_reserved(&i915->bdev, i915_gem_to_ttm(obj), >> size, >> + ttm_bo_type_kernel, >> i915_ttm_sys_placement(), >> + 0, &ctx, NULL, NULL, >> i915_ttm_internal_bo_destroy); >> + if (ret) { >> + ret = i915_ttm_err_to_gem(ret); >> + i915_gem_object_free(obj); >> + return ERR_PTR(ret); >> + } >> + >> + obj->ttm.created = true; >> obj->read_domains = I915_GEM_DOMAIN_CPU; >> obj->write_domain = I915_GEM_DOMAIN_CPU; >> - >> + obj->mem_flags &= ~I915_BO_FLAG_IOMEM; >> + obj->mem_flags |= I915_BO_FLAG_STRUCT_PAGE; >> cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : >> I915_CACHE_NONE; >> i915_gem_object_set_cache_coherency(obj, cache_level); >> + i915_gem_object_unlock(obj); >> >> return obj; >> } >> >> -/** >> - * i915_gem_object_create_internal: create an object with volatile >> pages >> - * @i915: the i915 device >> - * @size: the size in bytes of backing storage to allocate for the >> object >> - * >> - * Creates a new object that wraps some internal memory for private >> use. >> - * This object is not backed by swappable storage, and as such its >> contents >> - * are volatile and only valid whilst pinned. If the object is >> reaped by the >> - * shrinker, its pages and data will be discarded. Equally, it is >> not a full >> - * GEM object and so not valid for access from userspace. This makes >> it useful >> - * for hardware interfaces like ringbuffers (which are pinned from >> the time >> - * the request is written to the time the hardware stops accessing >> it), but >> - * not for contexts (which need to be preserved when not active for >> later >> - * reuse). Note that it is not cleared upon allocation. >> - */ >> -struct drm_i915_gem_object * >> -i915_gem_object_create_internal(struct drm_i915_private *i915, >> - phys_addr_t size) >> -{ >> - return __i915_gem_object_create_internal(i915, >> &i915_gem_object_internal_ops, size); > > While we don't have a TTM shmem backend ready yet for internal, > > Did you consider setting up just yet another region, > INTEL_REGION_INTERNAL, > .class = INTEL_MEMORY_SYSTEM and > .instance = 1, > > And make it create a TTM system region on integrated, and use > same region as INTEL_REGION_SMEM on dgfx. > > I think ttm should automatically map that to I915_PL_SYSTEM and the > backwards mapping in i915_ttm_region() should never get called since > the object is never moved. > > Then I figure it should suffice to just call > __i915_gem_ttm_object_init() and we could drop a lot of code. >
i briefly considered using a new fake region, but with current precedent mapping memory regions to real segemented memory areas I considered it an abuse of the semantics of memory regions.
If we are happy to have fake regions, I can revert it back to a previous design of using system region for discreet and add a fake region setup for integrated.
Would this be preferred over the current design?
> /Thomas > > > > >> -} >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_internal.h >> b/drivers/gpu/drm/i915/gem/i915_gem_internal.h >> index 6664e06112fc..524e1042b20f 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_internal.h >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_internal.h >> @@ -15,9 +15,4 @@ struct drm_i915_private; >> struct drm_i915_gem_object * >> i915_gem_object_create_internal(struct drm_i915_private *i915, >> phys_addr_t size); >> -struct drm_i915_gem_object * >> -__i915_gem_object_create_internal(struct drm_i915_private *i915, >> - const struct >> drm_i915_gem_object_ops *ops, >> - phys_addr_t size); >> - >> #endif /* __I915_GEM_INTERNAL_H__ */ >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c >> b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c >> index fdb3a1c18cb6..92195ead8c11 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c >> @@ -83,7 +83,7 @@ struct ttm_placement *i915_ttm_sys_placement(void) >> return &i915_sys_placement; >> } >> >> -static int i915_ttm_err_to_gem(int err) >> +int i915_ttm_err_to_gem(int err) >> { >> /* Fastpath */ >> if (likely(!err)) >> @@ -745,8 +745,8 @@ struct ttm_device_funcs *i915_ttm_driver(void) >> return &i915_ttm_bo_driver; >> } >> >> -static int __i915_ttm_get_pages(struct drm_i915_gem_object *obj, >> - struct ttm_placement *placement) >> +int __i915_ttm_get_pages(struct drm_i915_gem_object *obj, >> + struct ttm_placement *placement) >> { >> struct ttm_buffer_object *bo = i915_gem_to_ttm(obj); >> struct ttm_operation_ctx ctx = { >> @@ -871,8 +871,8 @@ static int i915_ttm_migrate(struct >> drm_i915_gem_object *obj, >> return __i915_ttm_migrate(obj, mr, obj->flags); >> } >> >> -static void i915_ttm_put_pages(struct drm_i915_gem_object *obj, >> - struct sg_table *st) >> +void i915_ttm_put_pages(struct drm_i915_gem_object *obj, >> + struct sg_table *st) >> { >> /* >> * We're currently not called from a shrinker, so put_pages() >> @@ -995,7 +995,7 @@ void i915_ttm_adjust_lru(struct >> drm_i915_gem_object *obj) >> * it's not idle, and using the TTM destroyed list handling could >> help us >> * benefit from that. >> */ >> -static void i915_ttm_delayed_free(struct drm_i915_gem_object *obj) >> +void i915_ttm_delayed_free(struct drm_i915_gem_object *obj) >> { >> GEM_BUG_ON(!obj->ttm.created); >> >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.h >> b/drivers/gpu/drm/i915/gem/i915_gem_ttm.h >> index 73e371aa3850..06701c46d8e2 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.h >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.h >> @@ -26,6 +26,7 @@ i915_gem_to_ttm(struct drm_i915_gem_object *obj) >> * i915 ttm gem object destructor. Internal use only. >> */ >> void i915_ttm_bo_destroy(struct ttm_buffer_object *bo); >> +void i915_ttm_internal_bo_destroy(struct ttm_buffer_object *bo); >> >> /** >> * i915_ttm_to_gem - Convert a struct ttm_buffer_object to an >> embedding >> @@ -37,8 +38,10 @@ void i915_ttm_bo_destroy(struct ttm_buffer_object >> *bo); >> static inline struct drm_i915_gem_object * >> i915_ttm_to_gem(struct ttm_buffer_object *bo) >> { >> - if (bo->destroy != i915_ttm_bo_destroy) >> + if (bo->destroy != i915_ttm_bo_destroy && >> + bo->destroy != i915_ttm_internal_bo_destroy) { >> return NULL; >> + } >> >> return container_of(bo, struct drm_i915_gem_object, >> __do_not_access); >> } >> @@ -66,6 +69,7 @@ i915_ttm_resource_get_st(struct drm_i915_gem_object >> *obj, >> struct ttm_resource *res); >> >> void i915_ttm_adjust_lru(struct drm_i915_gem_object *obj); >> +void i915_ttm_delayed_free(struct drm_i915_gem_object *obj); >> >> int i915_ttm_purge(struct drm_i915_gem_object *obj); >> >> @@ -92,4 +96,10 @@ static inline bool i915_ttm_cpu_maps_iomem(struct >> ttm_resource *mem) >> /* Once / if we support GGTT, this is also false for cached >> ttm_tts */ >> return mem->mem_type != I915_PL_SYSTEM; >> } >> + >> +int __i915_ttm_get_pages(struct drm_i915_gem_object *obj, >> + struct ttm_placement *placement); >> +void i915_ttm_put_pages(struct drm_i915_gem_object *obj, struct >> sg_table *st); >> +int i915_ttm_err_to_gem(int err); >> + >> #endif > >
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