[PATCH 1/2] drm/ttm: improve idle/busy handling v4
Christian König
ckoenig.leichtzumerken at gmail.com
Fri Feb 23 14:30:35 UTC 2024
Am 06.02.24 um 13:56 schrieb Christian König:
> Am 06.02.24 um 13:53 schrieb Thomas Hellström:
>> Hi, Christian,
>>
>> On Fri, 2024-01-26 at 15:09 +0100, Christian König wrote:
>>> Previously we would never try to move a BO into the preferred
>>> placements
>>> when it ever landed in a busy placement since those were considered
>>> compatible.
>>>
>>> Rework the whole handling and finally unify the idle and busy
>>> handling.
>>> ttm_bo_validate() is now responsible to try idle placement first and
>>> then
>>> use the busy placement if that didn't worked.
>>>
>>> Drawback is that we now always try the idle placement first for each
>>> validation which might cause some additional CPU overhead on
>>> overcommit.
>>>
>>> v2: fix kerneldoc warning and coding style
>>> v3: take care of XE as well
>>> v4: keep the ttm_bo_mem_space functionality as it is for now, only
>>> add
>>> new handling for ttm_bo_validate as suggested by Thomas
>>>
>>> Signed-off-by: Christian König <christian.koenig at amd.com>
>>> Reviewed-by: Zack Rusin <zack.rusin at broadcom.com> v3
>> Sending this through xe CI, will try to review asap.
>
> Take your time. At the moment people are bombarding me with work and I
> have only two hands and one head as well :(
So I've digged myself out of that hole and would rather like to get this
new feature into 6.9.
Any time to review it? I can also plan some time to review your LRU
changes next week.
Thanks,
Christian.
>
> Christian.
>
>>
>> /Thomas
>>
>>
>>> ---
>>> drivers/gpu/drm/ttm/ttm_bo.c | 231 +++++++++++++--------------
>>> --
>>> drivers/gpu/drm/ttm/ttm_resource.c | 16 +-
>>> include/drm/ttm/ttm_resource.h | 3 +-
>>> 3 files changed, 121 insertions(+), 129 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c
>>> b/drivers/gpu/drm/ttm/ttm_bo.c
>>> index ba3f09e2d7e6..b12f435542a9 100644
>>> --- a/drivers/gpu/drm/ttm/ttm_bo.c
>>> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
>>> @@ -724,64 +724,36 @@ static int ttm_bo_add_move_fence(struct
>>> ttm_buffer_object *bo,
>>> return ret;
>>> }
>>> -/*
>>> - * Repeatedly evict memory from the LRU for @mem_type until we
>>> create enough
>>> - * space, or we've evicted everything and there isn't enough space.
>>> - */
>>> -static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
>>> - const struct ttm_place *place,
>>> - struct ttm_resource **mem,
>>> - struct ttm_operation_ctx *ctx)
>>> -{
>>> - struct ttm_device *bdev = bo->bdev;
>>> - struct ttm_resource_manager *man;
>>> - struct ww_acquire_ctx *ticket;
>>> - int ret;
>>> -
>>> - man = ttm_manager_type(bdev, place->mem_type);
>>> - ticket = dma_resv_locking_ctx(bo->base.resv);
>>> - do {
>>> - ret = ttm_resource_alloc(bo, place, mem);
>>> - if (likely(!ret))
>>> - break;
>>> - if (unlikely(ret != -ENOSPC))
>>> - return ret;
>>> - ret = ttm_mem_evict_first(bdev, man, place, ctx,
>>> - ticket);
>>> - if (unlikely(ret != 0))
>>> - return ret;
>>> - } while (1);
>>> -
>>> - return ttm_bo_add_move_fence(bo, man, *mem, ctx-
>>>> no_wait_gpu);
>>> -}
>>> -
>>> /**
>>> - * ttm_bo_mem_space
>>> + * ttm_bo_alloc_resource - Allocate backing store for a BO
>>> *
>>> - * @bo: Pointer to a struct ttm_buffer_object. the data of which
>>> - * we want to allocate space for.
>>> - * @placement: Proposed new placement for the buffer object.
>>> - * @mem: A struct ttm_resource.
>>> + * @bo: Pointer to a struct ttm_buffer_object of which we want a
>>> resource for
>>> + * @placement: Proposed new placement for the buffer object
>>> * @ctx: if and how to sleep, lock buffers and alloc memory
>>> + * @force_space: If we should evict buffers to force space
>>> + * @res: The resulting struct ttm_resource.
>>> *
>>> - * Allocate memory space for the buffer object pointed to by @bo,
>>> using
>>> - * the placement flags in @placement, potentially evicting other
>>> idle buffer objects.
>>> - * This function may sleep while waiting for space to become
>>> available.
>>> + * Allocates a resource for the buffer object pointed to by @bo,
>>> using the
>>> + * placement flags in @placement, potentially evicting other buffer
>>> objects when
>>> + * @force_space is true.
>>> + * This function may sleep while waiting for resources to become
>>> available.
>>> * Returns:
>>> - * -EBUSY: No space available (only if no_wait == 1).
>>> + * -EBUSY: No space available (only if no_wait == true).
>>> * -ENOSPC: Could not allocate space for the buffer object, either
>>> due to
>>> * fragmentation or concurrent allocators.
>>> * -ERESTARTSYS: An interruptible sleep was interrupted by a signal.
>>> */
>>> -int ttm_bo_mem_space(struct ttm_buffer_object *bo,
>>> - struct ttm_placement *placement,
>>> - struct ttm_resource **mem,
>>> - struct ttm_operation_ctx *ctx)
>>> +static int ttm_bo_alloc_resource(struct ttm_buffer_object *bo,
>>> + struct ttm_placement *placement,
>>> + struct ttm_operation_ctx *ctx,
>>> + bool force_space,
>>> + struct ttm_resource **res)
>>> {
>>> struct ttm_device *bdev = bo->bdev;
>>> - bool type_found = false;
>>> + struct ww_acquire_ctx *ticket;
>>> int i, ret;
>>> + ticket = dma_resv_locking_ctx(bo->base.resv);
>>> ret = dma_resv_reserve_fences(bo->base.resv, 1);
>>> if (unlikely(ret))
>>> return ret;
>>> @@ -790,98 +762,73 @@ int ttm_bo_mem_space(struct ttm_buffer_object
>>> *bo,
>>> const struct ttm_place *place = &placement-
>>>> placement[i];
>>> struct ttm_resource_manager *man;
>>> - if (place->flags & TTM_PL_FLAG_FALLBACK)
>>> - continue;
>>> -
>>> man = ttm_manager_type(bdev, place->mem_type);
>>> if (!man || !ttm_resource_manager_used(man))
>>> continue;
>>> - type_found = true;
>>> - ret = ttm_resource_alloc(bo, place, mem);
>>> - if (ret == -ENOSPC)
>>> + if (place->flags & (force_space ?
>>> TTM_PL_FLAG_DESIRED :
>>> + TTM_PL_FLAG_FALLBACK))
>>> + continue;
>>> +
>>> + do {
>>> + ret = ttm_resource_alloc(bo, place, res);
>>> + if (unlikely(ret != -ENOSPC))
>>> + return ret;
>>> + if (likely(!ret) || !force_space)
>>> + break;
>>> +
>>> + ret = ttm_mem_evict_first(bdev, man, place,
>>> ctx,
>>> + ticket);
>>> + if (unlikely(ret == -EBUSY))
>>> + break;
>>> + if (unlikely(ret))
>>> + return ret;
>>> + } while (1);
>>> + if (ret)
>>> continue;
>>> - if (unlikely(ret))
>>> - goto error;
>>> - ret = ttm_bo_add_move_fence(bo, man, *mem, ctx-
>>>> no_wait_gpu);
>>> + ret = ttm_bo_add_move_fence(bo, man, *res, ctx-
>>>> no_wait_gpu);
>>> if (unlikely(ret)) {
>>> - ttm_resource_free(bo, mem);
>>> + ttm_resource_free(bo, res);
>>> if (ret == -EBUSY)
>>> continue;
>>> - goto error;
>>> + return ret;
>>> }
>>> return 0;
>>> }
>>> - for (i = 0; i < placement->num_placement; ++i) {
>>> - const struct ttm_place *place = &placement-
>>>> placement[i];
>>> - struct ttm_resource_manager *man;
>>> -
>>> - if (place->flags & TTM_PL_FLAG_DESIRED)
>>> - continue;
>>> -
>>> - man = ttm_manager_type(bdev, place->mem_type);
>>> - if (!man || !ttm_resource_manager_used(man))
>>> - continue;
>>> -
>>> - type_found = true;
>>> - ret = ttm_bo_mem_force_space(bo, place, mem, ctx);
>>> - if (likely(!ret))
>>> - return 0;
>>> -
>>> - if (ret && ret != -EBUSY)
>>> - goto error;
>>> - }
>>> -
>>> - ret = -ENOSPC;
>>> - if (!type_found) {
>>> - pr_err(TTM_PFX "No compatible memory type found\n");
>>> - ret = -EINVAL;
>>> - }
>>> -
>>> -error:
>>> - return ret;
>>> + return -ENOSPC;
>>> }
>>> -EXPORT_SYMBOL(ttm_bo_mem_space);
>>> -static int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
>>> - struct ttm_placement *placement,
>>> - struct ttm_operation_ctx *ctx)
>>> +/*
>>> + * ttm_bo_mem_space - Wrapper around ttm_bo_alloc_resource
>>> + *
>>> + * @bo: Pointer to a struct ttm_buffer_object of which we want a
>>> resource for
>>> + * @placement: Proposed new placement for the buffer object
>>> + * @res: The resulting struct ttm_resource.
>>> + * @ctx: if and how to sleep, lock buffers and alloc memory
>>> + *
>>> + * Tries both idle allocation and forcefully eviction of buffers.
>>> See
>>> + * ttm_bo_alloc_resource for details.
>>> + */
>>> +int ttm_bo_mem_space(struct ttm_buffer_object *bo,
>>> + struct ttm_placement *placement,
>>> + struct ttm_resource **res,
>>> + struct ttm_operation_ctx *ctx)
>>> {
>>> - struct ttm_resource *mem;
>>> - struct ttm_place hop;
>>> + bool force_space = false;
>>> int ret;
>>> - dma_resv_assert_held(bo->base.resv);
>>> + do {
>>> + ret = ttm_bo_alloc_resource(bo, placement, ctx,
>>> + force_space, res);
>>> + force_space = !force_space;
>>> + } while (ret == -ENOSPC && force_space);
>>> - /*
>>> - * Determine where to move the buffer.
>>> - *
>>> - * If driver determines move is going to need
>>> - * an extra step then it will return -EMULTIHOP
>>> - * and the buffer will be moved to the temporary
>>> - * stop and the driver will be called to make
>>> - * the second hop.
>>> - */
>>> - ret = ttm_bo_mem_space(bo, placement, &mem, ctx);
>>> - if (ret)
>>> - return ret;
>>> -bounce:
>>> - ret = ttm_bo_handle_move_mem(bo, mem, false, ctx, &hop);
>>> - if (ret == -EMULTIHOP) {
>>> - ret = ttm_bo_bounce_temp_buffer(bo, &mem, ctx,
>>> &hop);
>>> - if (ret)
>>> - goto out;
>>> - /* try and move to final place now. */
>>> - goto bounce;
>>> - }
>>> -out:
>>> - if (ret)
>>> - ttm_resource_free(bo, &mem);
>>> return ret;
>>> }
>>> +EXPORT_SYMBOL(ttm_bo_mem_space);
>>> /**
>>> * ttm_bo_validate
>>> @@ -902,6 +849,9 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
>>> struct ttm_placement *placement,
>>> struct ttm_operation_ctx *ctx)
>>> {
>>> + struct ttm_resource *res;
>>> + struct ttm_place hop;
>>> + bool force_space;
>>> int ret;
>>> dma_resv_assert_held(bo->base.resv);
>>> @@ -912,20 +862,53 @@ int ttm_bo_validate(struct ttm_buffer_object
>>> *bo,
>>> if (!placement->num_placement)
>>> return ttm_bo_pipeline_gutting(bo);
>>> - /* Check whether we need to move buffer. */
>>> - if (bo->resource && ttm_resource_compatible(bo->resource,
>>> placement))
>>> - return 0;
>>> + force_space = false;
>>> + do {
>>> + /* Check whether we need to move buffer. */
>>> + if (bo->resource &&
>>> + ttm_resource_compatible(bo->resource, placement,
>>> + force_space))
>>> + return 0;
>>> - /* Moving of pinned BOs is forbidden */
>>> - if (bo->pin_count)
>>> - return -EINVAL;
>>> + /* Moving of pinned BOs is forbidden */
>>> + if (bo->pin_count)
>>> + return -EINVAL;
>>> +
>>> + /*
>>> + * Determine where to move the buffer.
>>> + *
>>> + * If driver determines move is going to need
>>> + * an extra step then it will return -EMULTIHOP
>>> + * and the buffer will be moved to the temporary
>>> + * stop and the driver will be called to make
>>> + * the second hop.
>>> + */
>>> + ret = ttm_bo_alloc_resource(bo, placement, ctx,
>>> force_space,
>>> + &res);
>>> + force_space = !force_space;
>>> + if (ret == -ENOSPC)
>>> + continue;
>>> + if (ret)
>>> + return ret;
>>> +
>>> +bounce:
>>> + ret = ttm_bo_handle_move_mem(bo, res, false, ctx,
>>> &hop);
>>> + if (ret == -EMULTIHOP) {
>>> + ret = ttm_bo_bounce_temp_buffer(bo, &res,
>>> ctx, &hop);
>>> + /* try and move to final place now. */
>>> + if (!ret)
>>> + goto bounce;
>>> + }
>>> + if (ret) {
>>> + ttm_resource_free(bo, &res);
>>> + return ret;
>>> + }
>>> +
>>> + } while (ret && force_space);
>>> - ret = ttm_bo_move_buffer(bo, placement, ctx);
>>> /* For backward compatibility with userspace */
>>> if (ret == -ENOSPC)
>>> return -ENOMEM;
>>> - if (ret)
>>> - return ret;
>>> /*
>>> * We might need to add a TTM.
>>> diff --git a/drivers/gpu/drm/ttm/ttm_resource.c
>>> b/drivers/gpu/drm/ttm/ttm_resource.c
>>> index fb14f7716cf8..65155f2013ca 100644
>>> --- a/drivers/gpu/drm/ttm/ttm_resource.c
>>> +++ b/drivers/gpu/drm/ttm/ttm_resource.c
>>> @@ -295,11 +295,13 @@ bool ttm_resource_intersects(struct ttm_device
>>> *bdev,
>>> *
>>> * @res: the resource to check
>>> * @placement: the placement to check against
>>> + * @evicting: true if the caller is doing evictions
>>> *
>>> * Returns true if the placement is compatible.
>>> */
>>> bool ttm_resource_compatible(struct ttm_resource *res,
>>> - struct ttm_placement *placement)
>>> + struct ttm_placement *placement,
>>> + bool evicting)
>>> {
>>> struct ttm_buffer_object *bo = res->bo;
>>> struct ttm_device *bdev = bo->bdev;
>>> @@ -315,14 +317,20 @@ bool ttm_resource_compatible(struct
>>> ttm_resource *res,
>>> if (res->mem_type != place->mem_type)
>>> continue;
>>> + if (place->flags & (evicting ? TTM_PL_FLAG_DESIRED :
>>> + TTM_PL_FLAG_FALLBACK))
>>> + continue;
>>> +
>>> + if (place->flags & TTM_PL_FLAG_CONTIGUOUS &&
>>> + !(res->placement & TTM_PL_FLAG_CONTIGUOUS))
>>> + continue;
>>> +
>>> man = ttm_manager_type(bdev, res->mem_type);
>>> if (man->func->compatible &&
>>> !man->func->compatible(man, res, place, bo-
>>>> base.size))
>>> continue;
>>> - if ((!(place->flags & TTM_PL_FLAG_CONTIGUOUS) ||
>>> - (res->placement & TTM_PL_FLAG_CONTIGUOUS)))
>>> - return true;
>>> + return true;
>>> }
>>> return false;
>>> }
>>> diff --git a/include/drm/ttm/ttm_resource.h
>>> b/include/drm/ttm/ttm_resource.h
>>> index 1afa13f0c22b..7561023db43d 100644
>>> --- a/include/drm/ttm/ttm_resource.h
>>> +++ b/include/drm/ttm/ttm_resource.h
>>> @@ -366,7 +366,8 @@ bool ttm_resource_intersects(struct ttm_device
>>> *bdev,
>>> const struct ttm_place *place,
>>> size_t size);
>>> bool ttm_resource_compatible(struct ttm_resource *res,
>>> - struct ttm_placement *placement);
>>> + struct ttm_placement *placement,
>>> + bool evicting);
>>> void ttm_resource_set_bo(struct ttm_resource *res,
>>> struct ttm_buffer_object *bo);
>
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