Re: [PATCH v7 3/3] drm/i915/ttm: Use TTM for system memory

On Tue, 22 Jun 2021 at 10:34, Thomas Hellström thomas.hellstrom@linux.intel.com wrote:

For discrete, use TTM for both cached and WC system memory. That means we currently rely on the TTM memory accounting / shrinker. For cached system memory we should consider remaining shmem-backed, which can be implemented from our ttm_tt_populate callback. We can then also reuse our own very elaborate shrinker for that memory.

Signed-off-by: Thomas Hellström thomas.hellstrom@linux.intel.com Reviewed-by: Matthew Auld matthew.auld@intel.com

---

v2:

• Fix IS_ERR_OR_NULL() check to IS_ERR() (Reported by Matthew Auld)

v3:

• Commit message typo fix

v6:

• Fix TODO:s for supporting system memory with TTM.
• Update the object GEM region after a TTM move if compatible.
• Add a couple of warnings for shmem on DGFX.

---

drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 3 ++ drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 51 +++++++++++++++++----- drivers/gpu/drm/i915/i915_drv.h | 3 -- drivers/gpu/drm/i915/intel_memory_region.c | 7 ++- drivers/gpu/drm/i915/intel_memory_region.h | 8 ++++ 5 files changed, 58 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c index 7aa1c95c7b7d..3648ae1d6628 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -284,6 +284,7 @@ __i915_gem_object_release_shmem(struct drm_i915_gem_object *obj, bool needs_clflush) { GEM_BUG_ON(obj->mm.madv == __I915_MADV_PURGED);

•   GEM_WARN_ON(IS_DGFX(to_i915(obj->base.dev)));
  
    if (obj->mm.madv == I915_MADV_DONTNEED)
            obj->mm.dirty = false;
  

@@ -302,6 +303,7 @@ void i915_gem_object_put_pages_shmem(struct drm_i915_gem_object *obj, struct sg_ struct pagevec pvec; struct page *page;

•   GEM_WARN_ON(IS_DGFX(to_i915(obj->base.dev)));
    __i915_gem_object_release_shmem(obj, pages, true);
  
    i915_gem_gtt_finish_pages(obj, pages);
  

@@ -560,6 +562,7 @@ i915_gem_object_create_shmem_from_data(struct drm_i915_private *dev_priv, resource_size_t offset; int err;

•   GEM_WARN_ON(IS_DGFX(dev_priv));
    obj = i915_gem_object_create_shmem(dev_priv, round_up(size, PAGE_SIZE));
    if (IS_ERR(obj))
            return obj;
  

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c index 966b292d07da..07097f150065 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c @@ -286,6 +286,25 @@ static void i915_ttm_adjust_gem_after_move(struct drm_i915_gem_object *obj) { struct ttm_buffer_object *bo = i915_gem_to_ttm(obj); unsigned int cache_level;

•   unsigned int i;
  

•   /*
  

•    * If object was moved to an allowable region, update the object
  

•    * region to consider it migrated. Note that if it's currently not
  

•    * in an allowable region, it's evicted and we don't update the
  

•    * object region.
  

•    */
  

•   if (intel_region_to_ttm_type(obj->mm.region) != bo->resource->mem_type) {
  

•           for (i = 0; i < obj->mm.n_placements; ++i) {
  

•                   struct intel_memory_region *mr = obj->mm.placements[i];
  

•                   if (intel_region_to_ttm_type(mr) == bo->resource->mem_type &&
  

•                       mr != obj->mm.region) {
  

•                           intel_memory_region_put(obj->mm.region);
  

•                           obj->mm.region = intel_memory_region_get(mr);
  

break;?

i915_gem_object_{init, release}_memory_region?

There is also the region_link stuff, but I guess we can nuke that?

•                   }
  

•           }
  

•   }
  
    obj->mem_flags &= ~(I915_BO_FLAG_STRUCT_PAGE | I915_BO_FLAG_IOMEM);
  
  

@@ -615,13 +634,6 @@ static int i915_ttm_get_pages(struct drm_i915_gem_object *obj) /* Move to the requested placement. */ i915_ttm_placement_from_obj(obj, &requested, busy, &placement);

•   /*
  

•    * For now we support LMEM only with TTM.
  

•    * TODO: Remove with system support
  

•    */
  

•   GEM_BUG_ON(requested.mem_type < I915_PL_LMEM0 ||
  

•              busy[0].mem_type < I915_PL_LMEM0);
  

•   /* First try only the requested placement. No eviction. */
    real_num_busy = fetch_and_zero(&placement.num_busy_placement);
    ret = ttm_bo_validate(bo, &placement, &ctx);
  

@@ -635,9 +647,6 @@ static int i915_ttm_get_pages(struct drm_i915_gem_object *obj) ret == -EAGAIN) return ret;

•           /* TODO: Remove this when we support system as TTM. */
  

•           real_num_busy = 1;
  

•           /*
             * If the initial attempt fails, allow all accepted placements,
             * evicting if necessary.
  

@@ -872,3 +881,25 @@ int __i915_gem_ttm_object_init(struct intel_memory_region *mem,

    return 0;

}

+static const struct intel_memory_region_ops ttm_system_region_ops = {

•   .init_object = __i915_gem_ttm_object_init,
  

+};

+struct intel_memory_region * +i915_gem_ttm_system_setup(struct drm_i915_private *i915,

•                     u16 type, u16 instance)
  

+{

•   struct intel_memory_region *mr;
  

•   mr = intel_memory_region_create(i915, 0,
  

•                                   totalram_pages() << PAGE_SHIFT,
  

•                                   PAGE_SIZE, 0,
  

•                                   type, instance,
  

•                                   &ttm_system_region_ops);
  

•   if (IS_ERR(mr))
  

•           return mr;
  

•   intel_memory_region_set_name(mr, "system-ttm");
  

•   return mr;
  

+} diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 01e11fe38642..bfbfbae57573 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1751,9 +1751,6 @@ void i915_gem_cleanup_userptr(struct drm_i915_private *dev_priv); void i915_gem_init_early(struct drm_i915_private *dev_priv); void i915_gem_cleanup_early(struct drm_i915_private *dev_priv);

-struct intel_memory_region *i915_gem_shmem_setup(struct drm_i915_private *i915,

•                                            u16 type, u16 instance);
  

static inline void i915_gem_drain_freed_objects(struct drm_i915_private *i915) { /* diff --git a/drivers/gpu/drm/i915/intel_memory_region.c b/drivers/gpu/drm/i915/intel_memory_region.c index df59f884d37c..779eb2fa90b6 100644 --- a/drivers/gpu/drm/i915/intel_memory_region.c +++ b/drivers/gpu/drm/i915/intel_memory_region.c @@ -173,7 +173,12 @@ int intel_memory_regions_hw_probe(struct drm_i915_private *i915) instance = intel_region_map[i].instance; switch (type) { case INTEL_MEMORY_SYSTEM:

•                   mem = i915_gem_shmem_setup(i915, type, instance);
  

•                   if (IS_DGFX(i915))
  

•                           mem = i915_gem_ttm_system_setup(i915, type,
  

•                                                           instance);
  

•                   else
  

•                           mem = i915_gem_shmem_setup(i915, type,
  

•                                                      instance);
                    break;
            case INTEL_MEMORY_STOLEN_LOCAL:
                    mem = i915_gem_stolen_lmem_setup(i915, type, instance);
  

diff --git a/drivers/gpu/drm/i915/intel_memory_region.h b/drivers/gpu/drm/i915/intel_memory_region.h index 2be8433d373a..b1b9e461d53b 100644 --- a/drivers/gpu/drm/i915/intel_memory_region.h +++ b/drivers/gpu/drm/i915/intel_memory_region.h @@ -125,4 +125,12 @@ intel_memory_region_set_name(struct intel_memory_region *mem, int intel_memory_region_reserve(struct intel_memory_region *mem, resource_size_t offset, resource_size_t size);

+struct intel_memory_region * +i915_gem_ttm_system_setup(struct drm_i915_private *i915,

•                     u16 type, u16 instance);
  

+struct intel_memory_region * +i915_gem_shmem_setup(struct drm_i915_private *i915,

•                u16 type, u16 instance);
  

#endif

2.31.1