[PATCH 1/2] drm/ttm: fix busy memory to fail other user v6
Christian König
ckoenig.leichtzumerken at gmail.com
Tue May 7 11:24:53 UTC 2019
Am 07.05.19 um 13:22 schrieb zhoucm1:
>
>
> On 2019年05月07日 19:13, Koenig, Christian wrote:
>> Am 07.05.19 um 13:08 schrieb zhoucm1:
>>>
>>> On 2019年05月07日 18:53, Koenig, Christian wrote:
>>>> Am 07.05.19 um 11:36 schrieb Chunming Zhou:
>>>>> 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.
>>>>>
>>>>> Change-Id: I21423fb922f885465f13833c41df1e134364a8e7
>>>>> Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
>>>>> ---
>>>>> drivers/gpu/drm/ttm/ttm_bo.c | 113
>>>>> ++++++++++++++++++++++++++++++-----
>>>>> 1 file changed, 97 insertions(+), 16 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c
>>>>> b/drivers/gpu/drm/ttm/ttm_bo.c
>>>>> index 8502b3ed2d88..bbf1d14d00a7 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 +781,45 @@ 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)) {
>>>> A newline between declaration and code please.
>>>>
>>>>> + 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 +830,66 @@ 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 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 ttm_operation_ctx busy_ctx;
>>>>> +
>>>>> spin_unlock(&glob->lru_lock);
>>>>> - return -EBUSY;
>>>>> + /* check if other user occupy memory too long time */
>>>>> + if (!first_bo || !ctx || !ctx->resv ||
>>>>> !ctx->resv->lock.ctx) {
>>>>> + if (first_bo)
>>>>> + ttm_bo_put(first_bo);
>>>>> + return -EBUSY;
>>>>> + }
>>>>> + if (first_bo->resv == ctx->resv) {
>>>>> + ttm_bo_put(first_bo);
>>>>> + return -EBUSY;
>>>>> + }
>>>>> + if (ctx->interruptible)
>>>>> + ret = ww_mutex_lock_interruptible(&first_bo->resv->lock,
>>>>> + ctx->resv->lock.ctx);
>>>>> + else
>>>>> + ret = ww_mutex_lock(&first_bo->resv->lock,
>>>>> ctx->resv->lock.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 +898,15 @@ 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) {
>>>>> @@ -899,6 +972,13 @@ static int ttm_bo_mem_force_space(struct
>>>>> ttm_buffer_object *bo,
>>>>> {
>>>>> struct ttm_bo_device *bdev = bo->bdev;
>>>>> struct ttm_mem_type_manager *man = &bdev->man[mem_type];
>>>>> + struct ttm_operation_ctx native_ctx = {
>>>>> + .interruptible = false,
>>>>> + .no_wait_gpu = false,
>>>>> + .resv = bo->resv,
>>>>> + .flags = 0
>>>>> + };
>>>>> + struct ttm_operation_ctx *evict_ctx = ctx ? ctx : &native_ctx;
>>>> I thought we made the ctx parameter mandatory, didn't we? Could be
>>>> that
>>>> I remember that incorrectly.
>>> Prike said he see ctx->resv is null, in that case, code doesn't run
>>> into busy path.
>>> Oh, as you mentioned here, we need add .resv=bo->resv for every
>>> ttm_operation_ctx. That's a huge change which will cross all vendor
>>> drivers.
>>>
>>> Can we just force to evaluate evict_ctx->resv = bo->resv? That means
>>> we just add one extra line: evict_ctx->resv = bo->resv. How about that?
>> Well only if ctx->resv is NULL, otherwise we would overwrite some
>> reservation context given by the driver.
>>
>> Probably better to give the acquir_ctx as separate parameter to
>> ttm_mem_evict_first().
> still put acquire_ctx into ttm_operation_ctx? Then that's same ctx->resv.
> Current problem is we don't pass resv anywhere except ALLOW_EVICT case.
> If you have concern for overwritten, we have to do ".resv = bo->resv"
> in every ttm_operation_ctx definitions.
No, what I mean is to add the acquire_ctx as separate parameter to
ttm_mem_evict_first().
E.g. we only need it in this function and it is actually not related to
the ttm operation context filled in by the driver.
Christian.
>
> -David
>>
>> Christian.
>>
>>> -David
>>>> Christian.
>>>>
>>>>> int ret;
>>>>> do {
>>>>> @@ -907,7 +987,7 @@ 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, evict_ctx);
>>>>> if (unlikely(ret != 0))
>>>>> return ret;
>>>>> } while (1);
>>>>> @@ -1784,7 +1864,8 @@ 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;
>>>>> }
>
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