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drm/i915: Replace the pending_gpu_write flag with an explicit seqno
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As we always flush the GPU cache prior to emitting the breadcrumb, we no
longer have to worry about the deferred flush causing the
pending_gpu_write to be delayed. So we can instead utilize the known
last_write_seqno to hopefully minimise the wait times.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Chris Wilson authored and Daniel Vetter committed Jul 25, 2012
1 parent e5f1d96 commit 0201f1e
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Showing 5 changed files with 51 additions and 43 deletions.
9 changes: 5 additions & 4 deletions drivers/gpu/drm/i915/i915_debugfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -121,14 +121,15 @@ static const char *cache_level_str(int type)
static void
describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
{
seq_printf(m, "%p: %s%s %8zdKiB %04x %04x %d %d%s%s%s",
seq_printf(m, "%p: %s%s %8zdKiB %04x %04x %d %d %d%s%s%s",
&obj->base,
get_pin_flag(obj),
get_tiling_flag(obj),
obj->base.size / 1024,
obj->base.read_domains,
obj->base.write_domain,
obj->last_rendering_seqno,
obj->last_read_seqno,
obj->last_write_seqno,
obj->last_fenced_seqno,
cache_level_str(obj->cache_level),
obj->dirty ? " dirty" : "",
Expand Down Expand Up @@ -630,12 +631,12 @@ static void print_error_buffers(struct seq_file *m,
seq_printf(m, "%s [%d]:\n", name, count);

while (count--) {
seq_printf(m, " %08x %8u %04x %04x %08x%s%s%s%s%s%s%s",
seq_printf(m, " %08x %8u %04x %04x %x %x%s%s%s%s%s%s%s",
err->gtt_offset,
err->size,
err->read_domains,
err->write_domain,
err->seqno,
err->rseqno, err->wseqno,
pin_flag(err->pinned),
tiling_flag(err->tiling),
dirty_flag(err->dirty),
Expand Down
12 changes: 3 additions & 9 deletions drivers/gpu/drm/i915/i915_drv.h
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Original file line number Diff line number Diff line change
Expand Up @@ -221,7 +221,7 @@ struct drm_i915_error_state {
struct drm_i915_error_buffer {
u32 size;
u32 name;
u32 seqno;
u32 rseqno, wseqno;
u32 gtt_offset;
u32 read_domains;
u32 write_domain;
Expand Down Expand Up @@ -894,12 +894,6 @@ struct drm_i915_gem_object {
*/
unsigned int dirty:1;

/**
* This is set if the object has been written to since the last
* GPU flush.
*/
unsigned int pending_gpu_write:1;

/**
* Fence register bits (if any) for this object. Will be set
* as needed when mapped into the GTT.
Expand Down Expand Up @@ -992,7 +986,8 @@ struct drm_i915_gem_object {
struct intel_ring_buffer *ring;

/** Breadcrumb of last rendering to the buffer. */
uint32_t last_rendering_seqno;
uint32_t last_read_seqno;
uint32_t last_write_seqno;
/** Breadcrumb of last fenced GPU access to the buffer. */
uint32_t last_fenced_seqno;

Expand Down Expand Up @@ -1291,7 +1286,6 @@ void i915_gem_lastclose(struct drm_device *dev);
int i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
gfp_t gfpmask);
int __must_check i915_mutex_lock_interruptible(struct drm_device *dev);
int __must_check i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj);
int i915_gem_object_sync(struct drm_i915_gem_object *obj,
struct intel_ring_buffer *to);
void i915_gem_object_move_to_active(struct drm_i915_gem_object *obj,
Expand Down
66 changes: 39 additions & 27 deletions drivers/gpu/drm/i915/i915_gem.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1441,7 +1441,7 @@ i915_gem_object_move_to_active(struct drm_i915_gem_object *obj,
list_move_tail(&obj->mm_list, &dev_priv->mm.active_list);
list_move_tail(&obj->ring_list, &ring->active_list);

obj->last_rendering_seqno = seqno;
obj->last_read_seqno = seqno;

if (obj->fenced_gpu_access) {
obj->last_fenced_seqno = seqno;
Expand All @@ -1461,7 +1461,8 @@ static void
i915_gem_object_move_off_active(struct drm_i915_gem_object *obj)
{
list_del_init(&obj->ring_list);
obj->last_rendering_seqno = 0;
obj->last_read_seqno = 0;
obj->last_write_seqno = 0;
obj->last_fenced_seqno = 0;
}

Expand Down Expand Up @@ -1493,7 +1494,6 @@ i915_gem_object_move_to_inactive(struct drm_i915_gem_object *obj)
obj->fenced_gpu_access = false;

obj->active = 0;
obj->pending_gpu_write = false;
drm_gem_object_unreference(&obj->base);

WARN_ON(i915_verify_lists(dev));
Expand Down Expand Up @@ -1812,7 +1812,7 @@ i915_gem_retire_requests_ring(struct intel_ring_buffer *ring)
struct drm_i915_gem_object,
ring_list);

if (!i915_seqno_passed(seqno, obj->last_rendering_seqno))
if (!i915_seqno_passed(seqno, obj->last_read_seqno))
break;

if (obj->base.write_domain != 0)
Expand Down Expand Up @@ -2036,9 +2036,11 @@ i915_wait_seqno(struct intel_ring_buffer *ring, uint32_t seqno)
* Ensures that all rendering to the object has completed and the object is
* safe to unbind from the GTT or access from the CPU.
*/
int
i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj)
static __must_check int
i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
bool readonly)
{
u32 seqno;
int ret;

/* This function only exists to support waiting for existing rendering,
Expand All @@ -2049,13 +2051,27 @@ i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj)
/* If there is rendering queued on the buffer being evicted, wait for
* it.
*/
if (obj->active) {
ret = i915_wait_seqno(obj->ring, obj->last_rendering_seqno);
if (ret)
return ret;
i915_gem_retire_requests_ring(obj->ring);
if (readonly)
seqno = obj->last_write_seqno;
else
seqno = obj->last_read_seqno;
if (seqno == 0)
return 0;

ret = i915_wait_seqno(obj->ring, seqno);
if (ret)
return ret;

/* Manually manage the write flush as we may have not yet retired
* the buffer.
*/
if (obj->last_write_seqno &&
i915_seqno_passed(seqno, obj->last_write_seqno)) {
obj->last_write_seqno = 0;
obj->base.write_domain &= ~I915_GEM_GPU_DOMAINS;
}

i915_gem_retire_requests_ring(obj->ring);
return 0;
}

Expand All @@ -2074,10 +2090,10 @@ i915_gem_object_flush_active(struct drm_i915_gem_object *obj)
if (ret)
return ret;

ret = i915_gem_check_olr(obj->ring,
obj->last_rendering_seqno);
ret = i915_gem_check_olr(obj->ring, obj->last_read_seqno);
if (ret)
return ret;

i915_gem_retire_requests_ring(obj->ring);
}

Expand Down Expand Up @@ -2137,7 +2153,7 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
goto out;

if (obj->active) {
seqno = obj->last_rendering_seqno;
seqno = obj->last_read_seqno;
ring = obj->ring;
}

Expand Down Expand Up @@ -2192,11 +2208,11 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
return 0;

if (to == NULL || !i915_semaphore_is_enabled(obj->base.dev))
return i915_gem_object_wait_rendering(obj);
return i915_gem_object_wait_rendering(obj, false);

idx = intel_ring_sync_index(from, to);

seqno = obj->last_rendering_seqno;
seqno = obj->last_read_seqno;
if (seqno <= from->sync_seqno[idx])
return 0;

Expand Down Expand Up @@ -2940,11 +2956,9 @@ i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
if (ret)
return ret;

if (obj->pending_gpu_write || write) {
ret = i915_gem_object_wait_rendering(obj);
if (ret)
return ret;
}
ret = i915_gem_object_wait_rendering(obj, !write);
if (ret)
return ret;

i915_gem_object_flush_cpu_write_domain(obj);

Expand Down Expand Up @@ -3115,7 +3129,7 @@ i915_gem_object_finish_gpu(struct drm_i915_gem_object *obj)
return ret;
}

ret = i915_gem_object_wait_rendering(obj);
ret = i915_gem_object_wait_rendering(obj, false);
if (ret)
return ret;

Expand Down Expand Up @@ -3143,11 +3157,9 @@ i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write)
if (ret)
return ret;

if (write || obj->pending_gpu_write) {
ret = i915_gem_object_wait_rendering(obj);
if (ret)
return ret;
}
ret = i915_gem_object_wait_rendering(obj, !write);
if (ret)
return ret;

i915_gem_object_flush_gtt_write_domain(obj);

Expand Down
2 changes: 1 addition & 1 deletion drivers/gpu/drm/i915/i915_gem_execbuffer.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -954,7 +954,7 @@ i915_gem_execbuffer_move_to_active(struct list_head *objects,
i915_gem_object_move_to_active(obj, ring, seqno);
if (obj->base.write_domain) {
obj->dirty = 1;
obj->pending_gpu_write = true;
obj->last_write_seqno = seqno;
list_move_tail(&obj->gpu_write_list,
&ring->gpu_write_list);
if (obj->pin_count) /* check for potential scanout */
Expand Down
5 changes: 3 additions & 2 deletions drivers/gpu/drm/i915/i915_irq.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -950,7 +950,8 @@ static void capture_bo(struct drm_i915_error_buffer *err,
{
err->size = obj->base.size;
err->name = obj->base.name;
err->seqno = obj->last_rendering_seqno;
err->rseqno = obj->last_read_seqno;
err->wseqno = obj->last_write_seqno;
err->gtt_offset = obj->gtt_offset;
err->read_domains = obj->base.read_domains;
err->write_domain = obj->base.write_domain;
Expand Down Expand Up @@ -1045,7 +1046,7 @@ i915_error_first_batchbuffer(struct drm_i915_private *dev_priv,
if (obj->ring != ring)
continue;

if (i915_seqno_passed(seqno, obj->last_rendering_seqno))
if (i915_seqno_passed(seqno, obj->last_read_seqno))
continue;

if ((obj->base.read_domains & I915_GEM_DOMAIN_COMMAND) == 0)
Expand Down

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