[PATCH 37/55] drm/i915: Introduce i915_gem_active for request tracking

Chris Wilson
2016-07-25T17:39:55Z

In the next patch, request tracking is made more generic and for that we
need a new expanded struct and to separate out the logic changes from
the mechanical churn, we split out the structure renaming into this
patch.

v2: Writer's block. Add some spiel about why we track requests.
v3: Now i915_gem_active.
v4: Now with i915_gem_active_set() for attaching to the active request.
v5: Use i915_gem_active_set() from inside the retirement handlers

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_debugfs.c | 11 +++---
drivers/gpu/drm/i915/i915_drv.h | 9 +++--
drivers/gpu/drm/i915/i915_gem.c | 58 +++++++++++++++---------------
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 4 +--
drivers/gpu/drm/i915/i915_gem_fence.c | 6 ++--
drivers/gpu/drm/i915/i915_gem_request.h | 41 +++++++++++++++++++++
drivers/gpu/drm/i915/i915_gem_tiling.c | 2 +-
drivers/gpu/drm/i915/i915_gem_userptr.c | 2 +-
drivers/gpu/drm/i915/i915_gpu_error.c | 7 ++--
drivers/gpu/drm/i915/intel_display.c | 8 ++---
10 files changed, 93 insertions(+), 55 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index b638ecea0c03..f67892215136 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -155,10 +155,10 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
obj->base.write_domain);
for_each_engine_id(engine, dev_priv, id)
seq_printf(m, "%x ",
- i915_gem_request_get_seqno(obj->last_read_req[id]));
+ i915_gem_request_get_seqno(obj->last_read[id].request));
seq_printf(m, "] %x %x%s%s%s",
- i915_gem_request_get_seqno(obj->last_write_req),
- i915_gem_request_get_seqno(obj->last_fenced_req),
+ i915_gem_request_get_seqno(obj->last_write.request),
+ i915_gem_request_get_seqno(obj->last_fence.request),
i915_cache_level_str(to_i915(obj->base.dev), obj->cache_level),
obj->dirty ? " dirty" : "",
obj->madv == I915_MADV_DONTNEED ? " purgeable" : "");
@@ -195,9 +195,8 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
*t = '\0';
seq_printf(m, " (%s mappable)", s);
}
- if (obj->last_write_req != NULL)
- seq_printf(m, " (%s)",
- i915_gem_request_get_engine(obj->last_write_req)->name);
+ if (obj->last_write.request)
+ seq_printf(m, " (%s)", obj->last_write.request->engine->name);
if (obj->frontbuffer_bits)
seq_printf(m, " (frontbuffer: 0x%03x)", obj->frontbuffer_bits);
}
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 2abae63258a3..76b5611aba9e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2242,11 +2242,10 @@ struct drm_i915_gem_object {
* requests on one ring where the write request is older than the
* read request. This allows for the CPU to read from an active
* buffer by only waiting for the write to complete.
- * */
- struct drm_i915_gem_request *last_read_req[I915_NUM_ENGINES];
- struct drm_i915_gem_request *last_write_req;
- /** Breadcrumb of last fenced GPU access to the buffer. */
- struct drm_i915_gem_request *last_fenced_req;
+ */
+ struct i915_gem_active last_read[I915_NUM_ENGINES];
+ struct i915_gem_active last_write;
+ struct i915_gem_active last_fence;

/** Current tiling stride for the object, if it's tiled. */
uint32_t stride;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index bcc05dd2be5a..98dc97c8c2bf 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1353,23 +1353,23 @@ i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
int ret, i;

if (readonly) {
- if (obj->last_write_req != NULL) {
- ret = i915_wait_request(obj->last_write_req);
+ if (obj->last_write.request) {
+ ret = i915_wait_request(obj->last_write.request);
if (ret)
return ret;

- i = obj->last_write_req->engine->id;
- if (obj->last_read_req[i] == obj->last_write_req)
+ i = obj->last_write.request->engine->id;
+ if (obj->last_read[i].request == obj->last_write.request)
i915_gem_object_retire__read(obj, i);
else
i915_gem_object_retire__write(obj);
}
} else {
for (i = 0; i < I915_NUM_ENGINES; i++) {
- if (obj->last_read_req[i] == NULL)
+ if (!obj->last_read[i].request)
continue;

- ret = i915_wait_request(obj->last_read_req[i]);
+ ret = i915_wait_request(obj->last_read[i].request);
if (ret)
return ret;

@@ -1397,9 +1397,9 @@ i915_gem_object_retire_request(struct drm_i915_gem_object *obj,
{
int idx = req->engine->id;

- if (obj->last_read_req[idx] == req)
+ if (obj->last_read[idx].request == req)
i915_gem_object_retire__read(obj, idx);
- else if (obj->last_write_req == req)
+ else if (obj->last_write.request == req)
i915_gem_object_retire__write(obj);

if (!i915_reset_in_progress(&req->i915->gpu_error))
@@ -1428,7 +1428,7 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
if (readonly) {
struct drm_i915_gem_request *req;

- req = obj->last_write_req;
+ req = obj->last_write.request;
if (req == NULL)
return 0;

@@ -1437,7 +1437,7 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
for (i = 0; i < I915_NUM_ENGINES; i++) {
struct drm_i915_gem_request *req;

- req = obj->last_read_req[i];
+ req = obj->last_read[i].request;
if (req == NULL)
continue;

@@ -2375,7 +2375,7 @@ void i915_vma_move_to_active(struct i915_vma *vma,
obj->active |= intel_engine_flag(engine);

list_move_tail(&obj->engine_list[engine->id], &engine->active_list);
- i915_gem_request_assign(&obj->last_read_req[engine->id], req);
+ i915_gem_active_set(&obj->last_read[engine->id], req);

list_move_tail(&vma->vm_link, &vma->vm->active_list);
}
@@ -2383,10 +2383,10 @@ void i915_vma_move_to_active(struct i915_vma *vma,
static void
i915_gem_object_retire__write(struct drm_i915_gem_object *obj)
{
- GEM_BUG_ON(obj->last_write_req == NULL);
- GEM_BUG_ON(!(obj->active & intel_engine_flag(obj->last_write_req->engine)));
+ GEM_BUG_ON(!obj->last_write.request);
+ GEM_BUG_ON(!(obj->active & intel_engine_flag(obj->last_write.request->engine)));

- i915_gem_request_assign(&obj->last_write_req, NULL);
+ i915_gem_active_set(&obj->last_write, NULL);
intel_fb_obj_flush(obj, true, ORIGIN_CS);
}

@@ -2395,13 +2395,13 @@ i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int idx)
{
struct i915_vma *vma;

- GEM_BUG_ON(obj->last_read_req[idx] == NULL);
+ GEM_BUG_ON(!obj->last_read[idx].request);
GEM_BUG_ON(!(obj->active & (1 << idx)));

list_del_init(&obj->engine_list[idx]);
- i915_gem_request_assign(&obj->last_read_req[idx], NULL);
+ i915_gem_active_set(&obj->last_read[idx], NULL);

- if (obj->last_write_req && obj->last_write_req->engine->id == idx)
+ if (obj->last_write.request && obj->last_write.request->engine->id == idx)
i915_gem_object_retire__write(obj);

obj->active &= ~(1 << idx);
@@ -2420,7 +2420,7 @@ i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int idx)
list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
}

- i915_gem_request_assign(&obj->last_fenced_req, NULL);
+ i915_gem_active_set(&obj->last_fence, NULL);
i915_gem_object_put(obj);
}

@@ -2621,7 +2621,7 @@ i915_gem_retire_requests_ring(struct intel_engine_cs *engine)
struct drm_i915_gem_object,
engine_list[engine->id]);

- if (!list_empty(&obj->last_read_req[engine->id]->list))
+ if (!list_empty(&obj->last_read[engine->id].request->list))
break;

i915_gem_object_retire__read(obj, engine->id);
@@ -2754,7 +2754,7 @@ i915_gem_object_flush_active(struct drm_i915_gem_object *obj)
for (i = 0; i < I915_NUM_ENGINES; i++) {
struct drm_i915_gem_request *req;

- req = obj->last_read_req[i];
+ req = obj->last_read[i].request;
if (req == NULL)
continue;

@@ -2830,10 +2830,10 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
i915_gem_object_put(obj);

for (i = 0; i < I915_NUM_ENGINES; i++) {
- if (obj->last_read_req[i] == NULL)
+ if (!obj->last_read[i].request)
continue;

- req[n++] = i915_gem_request_get(obj->last_read_req[i]);
+ req[n++] = i915_gem_request_get(obj->last_read[i].request);
}

mutex_unlock(&dev->struct_mutex);
@@ -2924,12 +2924,12 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,

n = 0;
if (readonly) {
- if (obj->last_write_req)
- req[n++] = obj->last_write_req;
+ if (obj->last_write.request)
+ req[n++] = obj->last_write.request;
} else {
for (i = 0; i < I915_NUM_ENGINES; i++)
- if (obj->last_read_req[i])
- req[n++] = obj->last_read_req[i];
+ if (obj->last_read[i].request)
+ req[n++] = obj->last_read[i].request;
}
for (i = 0; i < n; i++) {
ret = __i915_gem_object_sync(obj, to, req[i]);
@@ -4030,12 +4030,12 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
for (i = 0; i < I915_NUM_ENGINES; i++) {
struct drm_i915_gem_request *req;

- req = obj->last_read_req[i];
+ req = obj->last_read[i].request;
if (req)
args->busy |= 1 << (16 + req->engine->exec_id);
}
- if (obj->last_write_req)
- args->busy |= obj->last_write_req->engine->exec_id;
+ if (obj->last_write.request)
+ args->busy |= obj->last_write.request->engine->exec_id;
}

unref:
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 83e76959a50c..e1dfdbd8fc2e 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1150,7 +1150,7 @@ i915_gem_execbuffer_move_to_active(struct list_head *vmas,

i915_vma_move_to_active(vma, req);
if (obj->base.write_domain) {
- i915_gem_request_assign(&obj->last_write_req, req);
+ i915_gem_active_set(&obj->last_write, req);

intel_fb_obj_invalidate(obj, ORIGIN_CS);

@@ -1158,7 +1158,7 @@ i915_gem_execbuffer_move_to_active(struct list_head *vmas,
obj->base.write_domain &= ~I915_GEM_GPU_DOMAINS;
}
if (entry->flags & EXEC_OBJECT_NEEDS_FENCE) {
- i915_gem_request_assign(&obj->last_fenced_req, req);
+ i915_gem_active_set(&obj->last_fence, req);
if (entry->flags & __EXEC_OBJECT_HAS_FENCE) {
struct drm_i915_private *dev_priv = engine->i915;
list_move_tail(&dev_priv->fence_regs[obj->fence_reg].lru_list,
diff --git a/drivers/gpu/drm/i915/i915_gem_fence.c b/drivers/gpu/drm/i915/i915_gem_fence.c
index 251d7a95af89..d16b385e79e9 100644
--- a/drivers/gpu/drm/i915/i915_gem_fence.c
+++ b/drivers/gpu/drm/i915/i915_gem_fence.c
@@ -261,12 +261,12 @@ static inline void i915_gem_object_fence_lost(struct drm_i915_gem_object *obj)
static int
i915_gem_object_wait_fence(struct drm_i915_gem_object *obj)
{
- if (obj->last_fenced_req) {
- int ret = i915_wait_request(obj->last_fenced_req);
+ if (obj->last_fence.request) {
+ int ret = i915_wait_request(obj->last_fence.request);
if (ret)
return ret;

- i915_gem_request_assign(&obj->last_fenced_req, NULL);
+ i915_gem_active_set(&obj->last_fence, NULL);
}

return 0;
diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
index 382ca5a163eb..5d2ea5ee03c2 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.h
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -249,4 +249,45 @@ static inline bool i915_spin_request(const struct drm_i915_gem_request *request,
__i915_spin_request(request, state, timeout_us));
}

+/* We treat requests as fences. This is not be to confused with our
+ * "fence registers" but pipeline synchronisation objects ala GL_ARB_sync.
+ * We use the fences to synchronize access from the CPU with activity on the
+ * GPU, for example, we should not rewrite an object's PTE whilst the GPU
+ * is reading them. We also track fences at a higher level to provide
+ * implicit synchronisation around GEM objects, e.g. set-domain will wait
+ * for outstanding GPU rendering before marking the object ready for CPU
+ * access, or a pageflip will wait until the GPU is complete before showing
+ * the frame on the scanout.
+ *
+ * In order to use a fence, the object must track the fence it needs to
+ * serialise with. For example, GEM objects want to track both read and
+ * write access so that we can perform concurrent read operations between
+ * the CPU and GPU engines, as well as waiting for all rendering to
+ * complete, or waiting for the last GPU user of a "fence register". The
+ * object then embeds a @i915_gem_active to track the most recent (in
+ * retirment order) request relevant for the desired mode of access.
+ * The @i915_gem_active is updated with i915_gem_request_mark_active() to
+ * track the most recent fence request, typically this is done as part of
+ * i915_vma_move_to_active().
+ *
+ * When the @i915_gem_active completes (is retired), it will
+ * signal its completion to the owner through a callback as well as mark
+ * itself as idle (i915_gem_active.request == NULL). The owner
+ * can then perform any action, such as delayed freeing of an active
+ * resource including itself.
+ */
+struct i915_gem_active {
+ struct drm_i915_gem_request *request;
+};
+
+static inline void
+i915_gem_active_set(struct i915_gem_active *active,
+ struct drm_i915_gem_request *request)
+{
+ i915_gem_request_assign(&active->request, request);
+}
+
+#define for_each_active(mask, idx) \
+ for (; mask ? idx = ffs(mask) - 1, 1 : 0; mask &= ~(1 << idx))
+
#endif /* I915_GEM_REQUEST_H */
diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
index e83fc2d0433c..00d796da65fb 100644
--- a/drivers/gpu/drm/i915/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
@@ -242,7 +242,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
}

obj->fence_dirty =
- obj->last_fenced_req ||
+ obj->last_fence.request ||
obj->fence_reg != I915_FENCE_REG_NONE;

obj->tiling_mode = args->tiling_mode;
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index e935b327f3f9..32f50a70ea42 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -74,7 +74,7 @@ static void wait_rendering(struct drm_i915_gem_object *obj)
for (i = 0; i < I915_NUM_ENGINES; i++) {
struct drm_i915_gem_request *req;

- req = obj->last_read_req[i];
+ req = obj->last_read[i].request;
if (req == NULL)
continue;

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 3d40b1dffc73..b0e75b3de44a 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -756,8 +756,8 @@ static void capture_bo(struct drm_i915_error_buffer *err,
err->size = obj->base.size;
err->name = obj->base.name;
for (i = 0; i < I915_NUM_ENGINES; i++)
- err->rseqno[i] = i915_gem_request_get_seqno(obj->last_read_req[i]);
- err->wseqno = i915_gem_request_get_seqno(obj->last_write_req);
+ err->rseqno[i] = i915_gem_request_get_seqno(obj->last_read[i].request);
+ err->wseqno = i915_gem_request_get_seqno(obj->last_write.request);
err->gtt_offset = vma->node.start;
err->read_domains = obj->base.read_domains;
err->write_domain = obj->base.write_domain;
@@ -769,8 +769,7 @@ static void capture_bo(struct drm_i915_error_buffer *err,
err->dirty = obj->dirty;
err->purgeable = obj->madv != I915_MADV_WILLNEED;
err->userptr = obj->userptr.mm != NULL;
- err->engine = obj->last_write_req ?
- i915_gem_request_get_engine(obj->last_write_req)->id : -1;
+ err->engine = obj->last_write.request ? obj->last_write.request->engine->id : -1;
err->cache_level = obj->cache_level;
}

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 5d4420b67642..bc204d103674 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11378,7 +11378,7 @@ static bool use_mmio_flip(struct intel_engine_cs *engine,
if (resv && !reservation_object_test_signaled_rcu(resv, false))
return true;

- return engine != i915_gem_request_get_engine(obj->last_write_req);
+ return engine != i915_gem_request_get_engine(obj->last_write.request);
}

static void skl_do_mmio_flip(struct intel_crtc *intel_crtc,
@@ -11681,7 +11681,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
} else if (IS_IVYBRIDGE(dev) || IS_HASWELL(dev)) {
engine = &dev_priv->engine[BCS];
} else if (INTEL_INFO(dev)->gen >= 7) {
- engine = i915_gem_request_get_engine(obj->last_write_req);
+ engine = i915_gem_request_get_engine(obj->last_write.request);
if (engine == NULL || engine->id != RCS)
engine = &dev_priv->engine[BCS];
} else {
@@ -11703,7 +11703,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
INIT_WORK(&work->mmio_work, intel_mmio_flip_work_func);

i915_gem_request_assign(&work->flip_queued_req,
- obj->last_write_req);
+ obj->last_write.request);

schedule_work(&work->mmio_work);
} else {
@@ -14051,7 +14051,7 @@ intel_prepare_plane_fb(struct drm_plane *plane,
to_intel_plane_state(new_state);

i915_gem_request_assign(&plane_state->wait_req,
- obj->last_write_req);
+ obj->last_write.request);
}

return ret;
--
2.8.1