[Intel-gfx] [PATCH 15/29] drm/i915: Add IRQ friendly request deference facility
Daniel, Thomas
thomas.daniel at intel.com
Tue Nov 11 12:54:00 CET 2014
> -----Original Message-----
> From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf
> Of John.C.Harrison at Intel.com
> Sent: Thursday, October 30, 2014 6:41 PM
> To: Intel-GFX at Lists.FreeDesktop.Org
> Subject: [Intel-gfx] [PATCH 15/29] drm/i915: Add IRQ friendly request
> deference facility
>
> From: John Harrison <John.C.Harrison at Intel.com>
>
> The next patch in the series converts some display related seqno usage to
> request structure usage. However, the request dereference introduced
> must be done from interrupt context. As the dereference potentially
> involves freeing the request structure and thus call lots of non-interrupt
> friendly code, this poses a problem.
>
> The solution is to add a IRQ friendly version of the dereference function. All
> this does is to add the request structure to a 'delayed free' list and return.
> The retire code, which is run periodically, then processes this list and does
> the actual dereferencing of the request structures.
>
> For: VIZ-4377
> Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 6 ++++++
> drivers/gpu/drm/i915/i915_gem.c | 28
> ++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/intel_lrc.c | 2 ++
> drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++
> drivers/gpu/drm/i915/intel_ringbuffer.h | 2 ++
> 5 files changed, 41 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h
> b/drivers/gpu/drm/i915/i915_drv.h index d184333..3e6082b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1951,6 +1951,9 @@ struct drm_i915_gem_request {
> struct drm_i915_file_private *file_priv;
> /** file_priv list entry for this request */
> struct list_head client_list;
> +
> + /** deferred free list for dereferencing from IRQ context */
> + struct list_head free_list;
> };
>
> void i915_gem_request_free(struct kref *req_ref); @@ -1976,9 +1979,12
> @@ i915_gem_request_reference(struct drm_i915_gem_request *req)
> static inline void i915_gem_request_unreference(struct
> drm_i915_gem_request *req) {
> + WARN_ON(!mutex_is_locked(&req->ring->dev->struct_mutex));
> kref_put(&req->ref, i915_gem_request_free); }
>
> +void i915_gem_request_unreference_irq(struct drm_i915_gem_request
> +*req);
> +
> static inline void i915_gem_request_assign(struct drm_i915_gem_request
> **pdst,
> struct drm_i915_gem_request *src)
> { diff --git a/drivers/gpu/drm/i915/i915_gem.c
> b/drivers/gpu/drm/i915/i915_gem.c index 9130aa1..e4cb253 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2635,6 +2635,18 @@ void i915_gem_reset(struct drm_device *dev)
> i915_gem_restore_fences(dev);
> }
>
> +void i915_gem_request_unreference_irq(struct drm_i915_gem_request
> *req)
> +{
> + struct intel_engine_cs *ring = req->ring;
> + unsigned long flags;
> +
> + /* Need to add the req to a deferred dereference list to be
> processed
> + * outside of interrupt time */
> + spin_lock_irqsave(&ring->reqlist_lock, flags);
> + list_add_tail(&req->free_list, &ring->delayed_free_list);
> + spin_unlock_irqrestore(&ring->reqlist_lock, flags); }
> +
> /**
> * This function clears the request list as sequence numbers are passed.
> */
> @@ -2708,6 +2720,21 @@ i915_gem_retire_requests_ring(struct
> intel_engine_cs *ring)
> ring->trace_irq_seqno = 0;
> }
>
> + while (!list_empty(&ring->delayed_free_list)) {
> + struct drm_i915_gem_request *request;
> + unsigned long flags;
> +
> + request = list_first_entry(&ring->delayed_free_list,
> + struct drm_i915_gem_request,
> + free_list);
> +
> + spin_lock_irqsave(&request->ring->reqlist_lock, flags);
> + list_del(&request->free_list);
> + spin_unlock_irqrestore(&request->ring->reqlist_lock, flags);
> +
> + i915_gem_request_unreference(request);
> + }
> +
> WARN_ON(i915_verify_lists(ring->dev));
> }
>
> @@ -4948,6 +4975,7 @@ init_ring_lists(struct intel_engine_cs *ring) {
> INIT_LIST_HEAD(&ring->active_list);
> INIT_LIST_HEAD(&ring->request_list);
> + INIT_LIST_HEAD(&ring->delayed_free_list);
Do we need this?
This list is initialized in logical_ring_init and init_ring_buffer anyway.
Thomas.
> }
>
> void i915_init_vm(struct drm_i915_private *dev_priv, diff --git
> a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index a6859ad..ba0d7b8 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -1249,7 +1249,9 @@ static int logical_ring_init(struct drm_device *dev,
> struct intel_engine_cs *rin
> ring->dev = dev;
> INIT_LIST_HEAD(&ring->active_list);
> INIT_LIST_HEAD(&ring->request_list);
> + spin_lock_init(&ring->reqlist_lock);
> init_waitqueue_head(&ring->irq_queue);
> + INIT_LIST_HEAD(&ring->delayed_free_list);
>
> INIT_LIST_HEAD(&ring->execlist_queue);
> spin_lock_init(&ring->execlist_lock);
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c
> b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 164236c..f225ba3 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -1807,6 +1807,8 @@ static int intel_init_ring_buffer(struct drm_device
> *dev,
> ring->dev = dev;
> INIT_LIST_HEAD(&ring->active_list);
> INIT_LIST_HEAD(&ring->request_list);
> + spin_lock_init(&ring->reqlist_lock);
> + INIT_LIST_HEAD(&ring->delayed_free_list);
> INIT_LIST_HEAD(&ring->execlist_queue);
> ringbuf->size = 32 * PAGE_SIZE;
> ringbuf->ring = ring;
> @@ -2506,6 +2508,7 @@ int intel_render_ring_init_dri(struct drm_device
> *dev, u64 start, u32 size)
> ring->dev = dev;
> INIT_LIST_HEAD(&ring->active_list);
> INIT_LIST_HEAD(&ring->request_list);
> + INIT_LIST_HEAD(&ring->delayed_free_list);
>
> ringbuf->size = size;
> ringbuf->effective_size = ringbuf->size; diff --git
> a/drivers/gpu/drm/i915/intel_ringbuffer.h
> b/drivers/gpu/drm/i915/intel_ringbuffer.h
> index 98b219d..0451233 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> @@ -261,6 +261,8 @@ struct intel_engine_cs {
> * outstanding.
> */
> struct list_head request_list;
> + spinlock_t reqlist_lock;
> + struct list_head delayed_free_list;
>
> /**
> * Do we have some not yet emitted requests outstanding?
> --
> 1.7.9.5
>
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