[PATCH 04/20] drm/radeon: convert fence to uint64_t v4
Jerome Glisse
j.glisse at gmail.com
Mon May 7 08:27:21 PDT 2012
On Mon, May 7, 2012 at 11:04 AM, Christian König
<deathsimple at vodafone.de> wrote:
> On 07.05.2012 16:39, Jerome Glisse wrote:
>>
>> On Mon, May 7, 2012 at 7:42 AM, Christian König<deathsimple at vodafone.de>
>> wrote:
>>>
>>> From: Jerome Glisse<jglisse at redhat.com>
>>>
>>> This convert fence to use uint64_t sequence number intention is
>>> to use the fact that uin64_t is big enough that we don't need to
>>> care about wrap around.
>>>
>>> Tested with and without writeback using 0xFFFFF000 as initial
>>> fence sequence and thus allowing to test the wrap around from
>>> 32bits to 64bits.
>>>
>>> v2: Add comment about possible race btw CPU& GPU, add comment
>>>
>>> stressing that we need 2 dword aligned for R600_WB_EVENT_OFFSET
>>> Read fence sequenc in reverse order of GPU write them so we
>>> mitigate the race btw CPU and GPU.
>>>
>>> v3: Drop the need for ring to emit the 64bits fence, and just have
>>> each ring emit the lower 32bits of the fence sequence. We
>>> handle the wrap over 32bits in fence_process.
>>>
>>> v4: Just a small optimization: Don't reread the last_seq value
>>> if loop restarts, since we already know its value anyway.
>>> Also start at zero not one for seq value and use pre instead
>>> of post increment in emmit, otherwise wait_empty will deadlock.
>>
>> Why changing that v3 was already good no deadlock. I started at 1
>> especialy for that, a signaled fence is set to 0 so it always compare
>> as signaled. Just using preincrement is exactly like starting at one.
>> I don't see the need for this change but if it makes you happy.
>
>
> Not exactly, the last emitted sequence is also used in
> radeon_fence_wait_empty. So when you use post increment
> radeon_fence_wait_empty will actually not wait for the last emitted fence to
> be signaled, but for last emitted + 1, so it practically waits forever.
>
> Without this change suspend (for example) will just lockup.
>
> Cheers,
> Christian.
Yeah you right, my tree had a fix for that. I probably messed up the
rebase patch at one point. Well as your version fix it i am fine with
it.
Cheers,
Jerome
>>
>> Cheers,
>> Jerome
>>>
>>> Signed-off-by: Jerome Glisse<jglisse at redhat.com>
>>> Signed-off-by: Christian König<deathsimple at vodafone.de>
>>> ---
>>> drivers/gpu/drm/radeon/radeon.h | 39 ++++++-----
>>> drivers/gpu/drm/radeon/radeon_fence.c | 116
>>> +++++++++++++++++++++++----------
>>> drivers/gpu/drm/radeon/radeon_ring.c | 9 ++-
>>> 3 files changed, 107 insertions(+), 57 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/radeon/radeon.h
>>> b/drivers/gpu/drm/radeon/radeon.h
>>> index e99ea81..cdf46bc 100644
>>> --- a/drivers/gpu/drm/radeon/radeon.h
>>> +++ b/drivers/gpu/drm/radeon/radeon.h
>>> @@ -100,28 +100,32 @@ extern int radeon_lockup_timeout;
>>> * Copy from radeon_drv.h so we don't have to include both and have
>>> conflicting
>>> * symbol;
>>> */
>>> -#define RADEON_MAX_USEC_TIMEOUT 100000 /* 100 ms */
>>> -#define RADEON_FENCE_JIFFIES_TIMEOUT (HZ / 2)
>>> +#define RADEON_MAX_USEC_TIMEOUT 100000 /* 100 ms
>>> */
>>> +#define RADEON_FENCE_JIFFIES_TIMEOUT (HZ / 2)
>>> /* RADEON_IB_POOL_SIZE must be a power of 2 */
>>> -#define RADEON_IB_POOL_SIZE 16
>>> -#define RADEON_DEBUGFS_MAX_COMPONENTS 32
>>> -#define RADEONFB_CONN_LIMIT 4
>>> -#define RADEON_BIOS_NUM_SCRATCH 8
>>> +#define RADEON_IB_POOL_SIZE 16
>>> +#define RADEON_DEBUGFS_MAX_COMPONENTS 32
>>> +#define RADEONFB_CONN_LIMIT 4
>>> +#define RADEON_BIOS_NUM_SCRATCH 8
>>>
>>> /* max number of rings */
>>> -#define RADEON_NUM_RINGS 3
>>> +#define RADEON_NUM_RINGS 3
>>> +
>>> +/* fence seq are set to this number when signaled */
>>> +#define RADEON_FENCE_SIGNALED_SEQ 0LL
>>> +#define RADEON_FENCE_NOTEMITED_SEQ (~0LL)
>>>
>>> /* internal ring indices */
>>> /* r1xx+ has gfx CP ring */
>>> -#define RADEON_RING_TYPE_GFX_INDEX 0
>>> +#define RADEON_RING_TYPE_GFX_INDEX 0
>>>
>>> /* cayman has 2 compute CP rings */
>>> -#define CAYMAN_RING_TYPE_CP1_INDEX 1
>>> -#define CAYMAN_RING_TYPE_CP2_INDEX 2
>>> +#define CAYMAN_RING_TYPE_CP1_INDEX 1
>>> +#define CAYMAN_RING_TYPE_CP2_INDEX 2
>>>
>>> /* hardcode those limit for now */
>>> -#define RADEON_VA_RESERVED_SIZE (8<< 20)
>>> -#define RADEON_IB_VM_MAX_SIZE (64<< 10)
>>> +#define RADEON_VA_RESERVED_SIZE (8<< 20)
>>> +#define RADEON_IB_VM_MAX_SIZE (64<< 10)
>>>
>>> /*
>>> * Errata workarounds.
>>> @@ -254,8 +258,9 @@ struct radeon_fence_driver {
>>> uint32_t scratch_reg;
>>> uint64_t gpu_addr;
>>> volatile uint32_t *cpu_addr;
>>> - atomic_t seq;
>>> - uint32_t last_seq;
>>> + /* seq is protected by ring emission lock */
>>> + uint64_t seq;
>>> + atomic64_t last_seq;
>>> unsigned long last_activity;
>>> wait_queue_head_t queue;
>>> struct list_head emitted;
>>> @@ -268,11 +273,9 @@ struct radeon_fence {
>>> struct kref kref;
>>> struct list_head list;
>>> /* protected by radeon_fence.lock */
>>> - uint32_t seq;
>>> - bool emitted;
>>> - bool signaled;
>>> + uint64_t seq;
>>> /* RB, DMA, etc. */
>>> - int ring;
>>> + unsigned ring;
>>> struct radeon_semaphore *semaphore;
>>> };
>>>
>>> diff --git a/drivers/gpu/drm/radeon/radeon_fence.c
>>> b/drivers/gpu/drm/radeon/radeon_fence.c
>>> index 5bb78bf..feb2bbc 100644
>>> --- a/drivers/gpu/drm/radeon/radeon_fence.c
>>> +++ b/drivers/gpu/drm/radeon/radeon_fence.c
>>> @@ -66,14 +66,14 @@ int radeon_fence_emit(struct radeon_device *rdev,
>>> struct radeon_fence *fence)
>>> unsigned long irq_flags;
>>>
>>> write_lock_irqsave(&rdev->fence_lock, irq_flags);
>>> - if (fence->emitted) {
>>> + if (fence->seq&& fence->seq< RADEON_FENCE_NOTEMITED_SEQ) {
>>>
>>> write_unlock_irqrestore(&rdev->fence_lock, irq_flags);
>>> return 0;
>>> }
>>> - fence->seq =
>>> atomic_add_return(1,&rdev->fence_drv[fence->ring].seq);
>>>
>>> + /* we are protected by the ring emission mutex */
>>> + fence->seq = ++rdev->fence_drv[fence->ring].seq;
>>> radeon_fence_ring_emit(rdev, fence->ring, fence);
>>> trace_radeon_fence_emit(rdev->ddev, fence->seq);
>>> - fence->emitted = true;
>>> /* are we the first fence on a previusly idle ring? */
>>> if (list_empty(&rdev->fence_drv[fence->ring].emitted)) {
>>> rdev->fence_drv[fence->ring].last_activity = jiffies;
>>> @@ -87,14 +87,60 @@ static bool radeon_fence_poll_locked(struct
>>> radeon_device *rdev, int ring)
>>> {
>>> struct radeon_fence *fence;
>>> struct list_head *i, *n;
>>> - uint32_t seq;
>>> + uint64_t seq, last_seq;
>>> + unsigned count_loop = 0;
>>> bool wake = false;
>>>
>>> - seq = radeon_fence_read(rdev, ring);
>>> - if (seq == rdev->fence_drv[ring].last_seq)
>>> - return false;
>>> + /* Note there is a scenario here for an infinite loop but it's
>>> + * very unlikely to happen. For it to happen, the current polling
>>> + * process need to be interrupted by another process and another
>>> + * process needs to update the last_seq btw the atomic read and
>>> + * xchg of the current process.
>>> + *
>>> + * More over for this to go in infinite loop there need to be
>>> + * continuously new fence signaled ie radeon_fence_read needs
>>> + * to return a different value each time for both the currently
>>> + * polling process and the other process that xchg the last_seq
>>> + * btw atomic read and xchg of the current process. And the
>>> + * value the other process set as last seq must be higher than
>>> + * the seq value we just read. Which means that current process
>>> + * need to be interrupted after radeon_fence_read and before
>>> + * atomic xchg.
>>> + *
>>> + * To be even more safe we count the number of time we loop and
>>> + * we bail after 10 loop just accepting the fact that we might
>>> + * have temporarly set the last_seq not to the true real last
>>> + * seq but to an older one.
>>> + */
>>> + last_seq = atomic64_read(&rdev->fence_drv[ring].last_seq);
>>> + do {
>>> + seq = radeon_fence_read(rdev, ring);
>>> + seq |= last_seq& 0xffffffff00000000LL;
>>>
>>> + if (seq< last_seq) {
>>> + seq += 0x100000000LL;
>>> + }
>>>
>>> - rdev->fence_drv[ring].last_seq = seq;
>>> + if (!wake&& seq == last_seq) {
>>>
>>> + return false;
>>> + }
>>> + /* If we loop over we don't want to return without
>>> + * checking if a fence is signaled as it means that the
>>> + * seq we just read is different from the previous on.
>>> + */
>>> + wake = true;
>>> + if ((count_loop++)> 10) {
>>> + /* We looped over too many time leave with the
>>> + * fact that we might have set an older fence
>>> + * seq then the current real last seq as signaled
>>> + * by the hw.
>>> + */
>>> + break;
>>> + }
>>> + last_seq = seq;
>>> + } while (atomic64_xchg(&rdev->fence_drv[ring].last_seq, seq)>
>>> seq);
>>> +
>>> + /* reset wake to false */
>>> + wake = false;
>>> rdev->fence_drv[ring].last_activity = jiffies;
>>>
>>> n = NULL;
>>> @@ -112,7 +158,7 @@ static bool radeon_fence_poll_locked(struct
>>> radeon_device *rdev, int ring)
>>> n = i->prev;
>>> list_move_tail(i,&rdev->fence_drv[ring].signaled);
>>>
>>> fence = list_entry(i, struct radeon_fence, list);
>>> - fence->signaled = true;
>>> + fence->seq = RADEON_FENCE_SIGNALED_SEQ;
>>> i = n;
>>> } while (i !=&rdev->fence_drv[ring].emitted);
>>>
>>> wake = true;
>>> @@ -128,7 +174,7 @@ static void radeon_fence_destroy(struct kref *kref)
>>> fence = container_of(kref, struct radeon_fence, kref);
>>> write_lock_irqsave(&fence->rdev->fence_lock, irq_flags);
>>> list_del(&fence->list);
>>> - fence->emitted = false;
>>> + fence->seq = RADEON_FENCE_NOTEMITED_SEQ;
>>> write_unlock_irqrestore(&fence->rdev->fence_lock, irq_flags);
>>> if (fence->semaphore)
>>> radeon_semaphore_free(fence->rdev, fence->semaphore);
>>> @@ -145,9 +191,7 @@ int radeon_fence_create(struct radeon_device *rdev,
>>> }
>>> kref_init(&((*fence)->kref));
>>> (*fence)->rdev = rdev;
>>> - (*fence)->emitted = false;
>>> - (*fence)->signaled = false;
>>> - (*fence)->seq = 0;
>>> + (*fence)->seq = RADEON_FENCE_NOTEMITED_SEQ;
>>> (*fence)->ring = ring;
>>> (*fence)->semaphore = NULL;
>>> INIT_LIST_HEAD(&(*fence)->list);
>>> @@ -163,18 +207,18 @@ bool radeon_fence_signaled(struct radeon_fence
>>> *fence)
>>> return true;
>>>
>>> write_lock_irqsave(&fence->rdev->fence_lock, irq_flags);
>>> - signaled = fence->signaled;
>>> + signaled = (fence->seq == RADEON_FENCE_SIGNALED_SEQ);
>>> /* if we are shuting down report all fence as signaled */
>>> if (fence->rdev->shutdown) {
>>> signaled = true;
>>> }
>>> - if (!fence->emitted) {
>>> + if (fence->seq == RADEON_FENCE_NOTEMITED_SEQ) {
>>> WARN(1, "Querying an unemitted fence : %p !\n", fence);
>>> signaled = true;
>>> }
>>> if (!signaled) {
>>> radeon_fence_poll_locked(fence->rdev, fence->ring);
>>> - signaled = fence->signaled;
>>> + signaled = (fence->seq == RADEON_FENCE_SIGNALED_SEQ);
>>> }
>>> write_unlock_irqrestore(&fence->rdev->fence_lock, irq_flags);
>>> return signaled;
>>> @@ -183,8 +227,8 @@ bool radeon_fence_signaled(struct radeon_fence
>>> *fence)
>>> int radeon_fence_wait(struct radeon_fence *fence, bool intr)
>>> {
>>> struct radeon_device *rdev;
>>> - unsigned long irq_flags, timeout;
>>> - u32 seq;
>>> + unsigned long irq_flags, timeout, last_activity;
>>> + uint64_t seq;
>>> int i, r;
>>> bool signaled;
>>>
>>> @@ -207,7 +251,9 @@ int radeon_fence_wait(struct radeon_fence *fence,
>>> bool intr)
>>> timeout = 1;
>>> }
>>> /* save current sequence value used to check for GPU
>>> lockups */
>>> - seq = rdev->fence_drv[fence->ring].last_seq;
>>> + seq =
>>> atomic64_read(&rdev->fence_drv[fence->ring].last_seq);
>>> + /* Save current last activity valuee, used to check for
>>> GPU lockups */
>>> + last_activity =
>>> rdev->fence_drv[fence->ring].last_activity;
>>> read_unlock_irqrestore(&rdev->fence_lock, irq_flags);
>>>
>>> trace_radeon_fence_wait_begin(rdev->ddev, seq);
>>> @@ -235,24 +281,23 @@ int radeon_fence_wait(struct radeon_fence *fence,
>>> bool intr)
>>> }
>>>
>>> write_lock_irqsave(&rdev->fence_lock, irq_flags);
>>> - /* check if sequence value has changed since
>>> last_activity */
>>> - if (seq != rdev->fence_drv[fence->ring].last_seq)
>>> {
>>> + /* test if somebody else has already decided that
>>> this is a lockup */
>>> + if (last_activity !=
>>> rdev->fence_drv[fence->ring].last_activity) {
>>> write_unlock_irqrestore(&rdev->fence_lock,
>>> irq_flags);
>>> continue;
>>> }
>>>
>>> - /* change sequence value on all rings, so nobody
>>> else things there is a lockup */
>>> - for (i = 0; i< RADEON_NUM_RINGS; ++i)
>>> - rdev->fence_drv[i].last_seq -= 0x10000;
>>> -
>>> - rdev->fence_drv[fence->ring].last_activity =
>>> jiffies;
>>> write_unlock_irqrestore(&rdev->fence_lock,
>>> irq_flags);
>>>
>>> if (radeon_ring_is_lockup(rdev,
>>> fence->ring,&rdev->ring[fence->ring])) {
>>>
>>> -
>>> /* good news we believe it's a lockup */
>>> - printk(KERN_WARNING "GPU lockup (waiting
>>> for 0x%08X last fence id 0x%08X)\n",
>>> - fence->seq, seq);
>>> + dev_warn(rdev->dev, "GPU lockup (waiting
>>> for 0x%016llx last fence id 0x%016llx)\n",
>>> + fence->seq, seq);
>>> +
>>> + /* change last activity so nobody else
>>> think there is a lockup */
>>> + for (i = 0; i< RADEON_NUM_RINGS; ++i) {
>>> + rdev->fence_drv[i].last_activity
>>> = jiffies;
>>> + }
>>>
>>> /* mark the ring as not ready any more */
>>> rdev->ring[fence->ring].ready = false;
>>> @@ -387,9 +432,9 @@ int radeon_fence_driver_start_ring(struct
>>> radeon_device *rdev, int ring)
>>> }
>>> rdev->fence_drv[ring].cpu_addr =&rdev->wb.wb[index/4];
>>>
>>> rdev->fence_drv[ring].gpu_addr = rdev->wb.gpu_addr + index;
>>> - radeon_fence_write(rdev,
>>> atomic_read(&rdev->fence_drv[ring]..seq), ring);
>>>
>>> + radeon_fence_write(rdev, rdev->fence_drv[ring].seq, ring);
>>> rdev->fence_drv[ring].initialized = true;
>>> - DRM_INFO("fence driver on ring %d use gpu addr 0x%08Lx and cpu
>>> addr 0x%p\n",
>>> + DRM_INFO("fence driver on ring %d use gpu addr 0x%016llx and cpu
>>> addr 0x%p\n",
>>> ring, rdev->fence_drv[ring].gpu_addr,
>>> rdev->fence_drv[ring].cpu_addr);
>>> write_unlock_irqrestore(&rdev->fence_lock, irq_flags);
>>> return 0;
>>> @@ -400,7 +445,8 @@ static void radeon_fence_driver_init_ring(struct
>>> radeon_device *rdev, int ring)
>>> rdev->fence_drv[ring].scratch_reg = -1;
>>> rdev->fence_drv[ring].cpu_addr = NULL;
>>> rdev->fence_drv[ring].gpu_addr = 0;
>>> - atomic_set(&rdev->fence_drv[ring].seq, 0);
>>> + rdev->fence_drv[ring].seq = 0;
>>> + atomic64_set(&rdev->fence_drv[ring].last_seq, 0);
>>> INIT_LIST_HEAD(&rdev->fence_drv[ring].emitted);
>>> INIT_LIST_HEAD(&rdev->fence_drv[ring].signaled);
>>> init_waitqueue_head(&rdev->fence_drv[ring].queue);
>>> @@ -458,12 +504,12 @@ static int radeon_debugfs_fence_info(struct
>>> seq_file *m, void *data)
>>> continue;
>>>
>>> seq_printf(m, "--- ring %d ---\n", i);
>>> - seq_printf(m, "Last signaled fence 0x%08X\n",
>>> - radeon_fence_read(rdev, i));
>>> + seq_printf(m, "Last signaled fence 0x%016lx\n",
>>> + atomic64_read(&rdev->fence_drv[i].last_seq));
>>> if (!list_empty(&rdev->fence_drv[i].emitted)) {
>>> fence =
>>> list_entry(rdev->fence_drv[i].emitted.prev,
>>> struct radeon_fence, list);
>>> - seq_printf(m, "Last emitted fence %p with
>>> 0x%08X\n",
>>> + seq_printf(m, "Last emitted fence %p with
>>> 0x%016llx\n",
>>> fence, fence->seq);
>>> }
>>> }
>>> diff --git a/drivers/gpu/drm/radeon/radeon_ring.c
>>> b/drivers/gpu/drm/radeon/radeon_ring.c
>>> index a4d60ae..4ae222b 100644
>>> --- a/drivers/gpu/drm/radeon/radeon_ring.c
>>> +++ b/drivers/gpu/drm/radeon/radeon_ring.c
>>> @@ -82,7 +82,7 @@ bool radeon_ib_try_free(struct radeon_device *rdev,
>>> struct radeon_ib *ib)
>>> bool done = false;
>>>
>>> /* only free ib which have been emited */
>>> - if (ib->fence&& ib->fence->emitted) {
>>> + if (ib->fence&& ib->fence->seq< RADEON_FENCE_NOTEMITED_SEQ) {
>>>
>>> if (radeon_fence_signaled(ib->fence)) {
>>> radeon_fence_unref(&ib->fence);
>>> radeon_sa_bo_free(rdev,&ib->sa_bo);
>>>
>>> @@ -149,8 +149,9 @@ retry:
>>> /* this should be rare event, ie all ib scheduled none signaled
>>> yet.
>>> */
>>> for (i = 0; i< RADEON_IB_POOL_SIZE; i++) {
>>> - if (rdev->ib_pool.ibs[idx].fence&&
>>> rdev->ib_pool.ibs[idx].fence->emitted) {
>>>
>>> - r =
>>> radeon_fence_wait(rdev->ib_pool.ibs[idx].fence, false);
>>> + struct radeon_fence *fence =
>>> rdev->ib_pool.ibs[idx].fence;
>>> + if (fence&& fence->seq< RADEON_FENCE_NOTEMITED_SEQ) {
>>>
>>> + r = radeon_fence_wait(fence, false);
>>> if (!r) {
>>> goto retry;
>>> }
>>> @@ -173,7 +174,7 @@ void radeon_ib_free(struct radeon_device *rdev,
>>> struct radeon_ib **ib)
>>> return;
>>> }
>>> radeon_mutex_lock(&rdev->ib_pool.mutex);
>>> - if (tmp->fence&& !tmp->fence->emitted) {
>>> + if (tmp->fence&& tmp->fence->seq == RADEON_FENCE_NOTEMITED_SEQ)
>>> {
>>> radeon_sa_bo_free(rdev,&tmp->sa_bo);
>>> radeon_fence_unref(&tmp->fence);
>>> }
>>> --
>>> 1.7.5.4
>>>
>
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