[PATCH 02/11] drm/ttm: fix busy memory to fail other user v8
Christian König
ckoenig.leichtzumerken at gmail.com
Wed May 15 09:28:23 UTC 2019
Am 15.05.19 um 11:27 schrieb Christian König:
> Am 15.05.19 um 10:45 schrieb Daniel Vetter:
>> On Wed, May 15, 2019 at 10:38:28AM +0200, Daniel Vetter wrote:
>>> On Tue, May 14, 2019 at 02:31:18PM +0200, Christian König wrote:
>>>> From: Chunming Zhou <david1.zhou at amd.com>
>>>>
>>>> heavy gpu job could occupy memory long time, which lead other user
>>>> fail to get memory.
>>>>
>>>> basically pick up Christian idea:
>>>>
>>>> 1. Reserve the BO in DC using a ww_mutex ticket (trivial).
>>>> 2. If we then run into this EBUSY condition in TTM check if the BO
>>>> we need memory for (or rather the ww_mutex of its reservation
>>>> object) has a ticket assigned.
>>>> 3. If we have a ticket we grab a reference to the first BO on the
>>>> LRU, drop the LRU lock and try to grab the reservation lock with
>>>> the ticket.
>>>> 4. If getting the reservation lock with the ticket succeeded we
>>>> check if the BO is still the first one on the LRU in question (the
>>>> BO could have moved).
>>>> 5. If the BO is still the first one on the LRU in question we try
>>>> to evict it as we would evict any other BO.
>>>> 6. If any of the "If's" above fail we just back off and return -EBUSY.
>>>>
>>>> v2: fix some minor check
>>>> v3: address Christian v2 comments.
>>>> v4: fix some missing
>>>> v5: handle first_bo unlock and bo_get/put
>>>> v6: abstract unified iterate function, and handle all possible
>>>> usecase not only pinned bo.
>>>> v7: pass request bo->resv to ttm_bo_evict_first
>>>> v8 (chk): minimal coding style fix
>>>>
>>>> Change-Id: I21423fb922f885465f13833c41df1e134364a8e7
>>>> Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
>>>> Reviewed-by: Christian König <christian.koenig at amd.com>
>>> I think this closes a big gap between ttm and the bkl/struct_mutex
>>> drivers - it's much easier to guarantee you can evict everything if
>>> there's only a single lock :-)
>>>
>>> Would be absolutely awesome if we could extract this as some kind of
>>> building block, like we've done with lots of other ttm concepts already
>>> (reservation_obj, fences, ...).
>>>
>>> Just an aside really.
>> Ofc this is meant as a comment on the entire patch series, without
>> all the
>> other patches to make sure BO always stay on a relevant LRU there's
>> still
>> gaps in the guaranteed forward progress eviction algorithm.
>
> Yeah, the problem surfaced because of patch #4. Previously TTM would
> have just ignored all errors and continued to try different placements
> and only return -ENOMEM when we ran out of a possible placements.
>
> I probably need to either fix patch #4 or reorder the patches.
Ups, please ignore. I accidentally replied to the wrong mail.
Christian.
>
> Thanks for the note,
> Christian.
>
>> -Daniel
>>
>>> -Daniel
>>>
>>>> ---
>>>> drivers/gpu/drm/ttm/ttm_bo.c | 113
>>>> +++++++++++++++++++++++++++++------
>>>> 1 file changed, 96 insertions(+), 17 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c
>>>> b/drivers/gpu/drm/ttm/ttm_bo.c
>>>> index 2845fceb2fbd..e634d3a36923 100644
>>>> --- a/drivers/gpu/drm/ttm/ttm_bo.c
>>>> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
>>>> @@ -766,11 +766,13 @@ EXPORT_SYMBOL(ttm_bo_eviction_valuable);
>>>> * b. Otherwise, trylock it.
>>>> */
>>>> static bool ttm_bo_evict_swapout_allowable(struct
>>>> ttm_buffer_object *bo,
>>>> - struct ttm_operation_ctx *ctx, bool *locked)
>>>> + struct ttm_operation_ctx *ctx, bool *locked, bool *busy)
>>>> {
>>>> bool ret = false;
>>>> *locked = false;
>>>> + if (busy)
>>>> + *busy = false;
>>>> if (bo->resv == ctx->resv) {
>>>> reservation_object_assert_held(bo->resv);
>>>> if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT
>>>> @@ -779,35 +781,46 @@ static bool
>>>> ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo,
>>>> } else {
>>>> *locked = reservation_object_trylock(bo->resv);
>>>> ret = *locked;
>>>> + if (!ret && busy)
>>>> + *busy = true;
>>>> }
>>>> return ret;
>>>> }
>>>> -static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
>>>> - uint32_t mem_type,
>>>> - const struct ttm_place *place,
>>>> - struct ttm_operation_ctx *ctx)
>>>> +static struct ttm_buffer_object*
>>>> +ttm_mem_find_evitable_bo(struct ttm_bo_device *bdev,
>>>> + struct ttm_mem_type_manager *man,
>>>> + const struct ttm_place *place,
>>>> + struct ttm_operation_ctx *ctx,
>>>> + struct ttm_buffer_object **first_bo,
>>>> + bool *locked)
>>>> {
>>>> - struct ttm_bo_global *glob = bdev->glob;
>>>> - struct ttm_mem_type_manager *man = &bdev->man[mem_type];
>>>> struct ttm_buffer_object *bo = NULL;
>>>> - bool locked = false;
>>>> - unsigned i;
>>>> - int ret;
>>>> + int i;
>>>> - spin_lock(&glob->lru_lock);
>>>> + if (first_bo)
>>>> + *first_bo = NULL;
>>>> for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
>>>> list_for_each_entry(bo, &man->lru[i], lru) {
>>>> - if (!ttm_bo_evict_swapout_allowable(bo, ctx, &locked))
>>>> + bool busy = false;
>>>> +
>>>> + if (!ttm_bo_evict_swapout_allowable(bo, ctx, locked,
>>>> + &busy)) {
>>>> + if (first_bo && !(*first_bo) && busy) {
>>>> + ttm_bo_get(bo);
>>>> + *first_bo = bo;
>>>> + }
>>>> continue;
>>>> + }
>>>> if (place && !bdev->driver->eviction_valuable(bo,
>>>> place)) {
>>>> - if (locked)
>>>> + if (*locked)
>>>> reservation_object_unlock(bo->resv);
>>>> continue;
>>>> }
>>>> +
>>>> break;
>>>> }
>>>> @@ -818,9 +831,69 @@ static int ttm_mem_evict_first(struct
>>>> ttm_bo_device *bdev,
>>>> bo = NULL;
>>>> }
>>>> + return bo;
>>>> +}
>>>> +
>>>> +static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
>>>> + uint32_t mem_type,
>>>> + const struct ttm_place *place,
>>>> + struct ttm_operation_ctx *ctx,
>>>> + struct reservation_object *request_resv)
>>>> +{
>>>> + struct ttm_bo_global *glob = bdev->glob;
>>>> + struct ttm_mem_type_manager *man = &bdev->man[mem_type];
>>>> + struct ttm_buffer_object *bo = NULL, *first_bo = NULL;
>>>> + bool locked = false;
>>>> + int ret;
>>>> +
>>>> + spin_lock(&glob->lru_lock);
>>>> + bo = ttm_mem_find_evitable_bo(bdev, man, place, ctx, &first_bo,
>>>> + &locked);
>>>> if (!bo) {
>>>> + struct ww_acquire_ctx *acquire_ctx = request_resv->lock.ctx;
>>>> + struct ttm_operation_ctx busy_ctx;
>>>> +
>>>> spin_unlock(&glob->lru_lock);
>>>> - return -EBUSY;
>>>> + /* check if other user occupy memory too long time */
>>>> + if (!first_bo || !request_resv || !request_resv->lock.ctx) {
>>>> + if (first_bo)
>>>> + ttm_bo_put(first_bo);
>>>> + return -EBUSY;
>>>> + }
>>>> + if (first_bo->resv == request_resv) {
>>>> + ttm_bo_put(first_bo);
>>>> + return -EBUSY;
>>>> + }
>>>> + if (ctx->interruptible)
>>>> + ret = ww_mutex_lock_interruptible(&first_bo->resv->lock,
>>>> + acquire_ctx);
>>>> + else
>>>> + ret = ww_mutex_lock(&first_bo->resv->lock,
>>>> + acquire_ctx);
>>>> + if (ret) {
>>>> + ttm_bo_put(first_bo);
>>>> + return ret;
>>>> + }
>>>> + spin_lock(&glob->lru_lock);
>>>> + /* previous busy resv lock is held by above, idle now,
>>>> + * so let them evictable.
>>>> + */
>>>> + busy_ctx.interruptible = ctx->interruptible;
>>>> + busy_ctx.no_wait_gpu = ctx->no_wait_gpu;
>>>> + busy_ctx.resv = first_bo->resv;
>>>> + busy_ctx.flags = TTM_OPT_FLAG_ALLOW_RES_EVICT;
>>>> +
>>>> + bo = ttm_mem_find_evitable_bo(bdev, man, place, &busy_ctx,
>>>> NULL,
>>>> + &locked);
>>>> + if (bo && (bo->resv == first_bo->resv))
>>>> + locked = true;
>>>> + else if (bo)
>>>> + ww_mutex_unlock(&first_bo->resv->lock);
>>>> + if (!bo) {
>>>> + spin_unlock(&glob->lru_lock);
>>>> + ttm_bo_put(first_bo);
>>>> + return -EBUSY;
>>>> + }
>>>> }
>>>> kref_get(&bo->list_kref);
>>>> @@ -829,11 +902,15 @@ static int ttm_mem_evict_first(struct
>>>> ttm_bo_device *bdev,
>>>> ret = ttm_bo_cleanup_refs(bo, ctx->interruptible,
>>>> ctx->no_wait_gpu, locked);
>>>> kref_put(&bo->list_kref, ttm_bo_release_list);
>>>> + if (first_bo)
>>>> + ttm_bo_put(first_bo);
>>>> return ret;
>>>> }
>>>> ttm_bo_del_from_lru(bo);
>>>> spin_unlock(&glob->lru_lock);
>>>> + if (first_bo)
>>>> + ttm_bo_put(first_bo);
>>>> ret = ttm_bo_evict(bo, ctx);
>>>> if (locked) {
>>>> @@ -907,7 +984,7 @@ static int ttm_bo_mem_force_space(struct
>>>> ttm_buffer_object *bo,
>>>> return ret;
>>>> if (mem->mm_node)
>>>> break;
>>>> - ret = ttm_mem_evict_first(bdev, mem_type, place, ctx);
>>>> + ret = ttm_mem_evict_first(bdev, mem_type, place, ctx,
>>>> bo->resv);
>>>> if (unlikely(ret != 0))
>>>> return ret;
>>>> } while (1);
>>>> @@ -1401,7 +1478,8 @@ static int ttm_bo_force_list_clean(struct
>>>> ttm_bo_device *bdev,
>>>> for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
>>>> while (!list_empty(&man->lru[i])) {
>>>> spin_unlock(&glob->lru_lock);
>>>> - ret = ttm_mem_evict_first(bdev, mem_type, NULL, &ctx);
>>>> + ret = ttm_mem_evict_first(bdev, mem_type, NULL, &ctx,
>>>> + NULL);
>>>> if (ret)
>>>> return ret;
>>>> spin_lock(&glob->lru_lock);
>>>> @@ -1772,7 +1850,8 @@ int ttm_bo_swapout(struct ttm_bo_global
>>>> *glob, struct ttm_operation_ctx *ctx)
>>>> spin_lock(&glob->lru_lock);
>>>> for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
>>>> list_for_each_entry(bo, &glob->swap_lru[i], swap) {
>>>> - if (ttm_bo_evict_swapout_allowable(bo, ctx, &locked)) {
>>>> + if (ttm_bo_evict_swapout_allowable(bo, ctx, &locked,
>>>> + NULL)) {
>>>> ret = 0;
>>>> break;
>>>> }
>>>> --
>>>> 2.17.1
>>>>
>>>> _______________________________________________
>>>> dri-devel mailing list
>>>> dri-devel at lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>> --
>>> Daniel Vetter
>>> Software Engineer, Intel Corporation
>>> http://blog.ffwll.ch
>
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