On Mon, Aug 09, 2021 at 04:40:11PM +0200, Daniel Vetter wrote:
On Mon, Aug 09, 2021 at 04:37:55PM +0200, Daniel Vetter wrote:
On Tue, Aug 03, 2021 at 03:29:12PM -0700, Matthew Brost wrote:
Introduce context parent-child relationship. Once this relationship is created all pinning / unpinning operations are directed to the parent context. The parent context is responsible for pinning all of its' children and itself.
This is a precursor to the full GuC multi-lrc implementation but aligns to how GuC mutli-lrc interface is defined - a single H2G is used register / deregister all of the contexts simultaneously.
Subsequent patches in the series will implement the pinning / unpinning operations for parent / child contexts.
Signed-off-by: Matthew Brost matthew.brost@intel.com
drivers/gpu/drm/i915/gt/intel_context.c | 29 +++++++++++++++++++ drivers/gpu/drm/i915/gt/intel_context.h | 18 ++++++++++++ drivers/gpu/drm/i915/gt/intel_context_types.h | 12 ++++++++ 3 files changed, 59 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c index 745e84c72c90..8cb92b10b547 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.c +++ b/drivers/gpu/drm/i915/gt/intel_context.c @@ -395,6 +395,8 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine) spin_lock_init(&ce->guc_state.lock); INIT_LIST_HEAD(&ce->guc_state.fences);
- INIT_LIST_HEAD(&ce->guc_child_list);
- spin_lock_init(&ce->guc_active.lock); INIT_LIST_HEAD(&ce->guc_active.requests);
@@ -414,10 +416,17 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
void intel_context_fini(struct intel_context *ce) {
struct intel_context *child, *next;
if (ce->timeline) intel_timeline_put(ce->timeline); i915_vm_put(ce->vm);
/* Need to put the creation ref for the children */
if (intel_context_is_parent(ce))
for_each_child_safe(ce, child, next)intel_context_put(child);mutex_destroy(&ce->pin_mutex); i915_active_fini(&ce->active);
} @@ -533,6 +542,26 @@ struct i915_request *intel_context_find_active_request(struct intel_context *ce) return active; }
+void intel_context_bind_parent_child(struct intel_context *parent,
struct intel_context *child)+{
- /*
* Callers responsibility to validate that this function is used* correctly but we use GEM_BUG_ON here ensure that they do.*/- GEM_BUG_ON(!intel_engine_uses_guc(parent->engine));
- GEM_BUG_ON(intel_context_is_pinned(parent));
- GEM_BUG_ON(intel_context_is_child(parent));
- GEM_BUG_ON(intel_context_is_pinned(child));
- GEM_BUG_ON(intel_context_is_child(child));
- GEM_BUG_ON(intel_context_is_parent(child));
- parent->guc_number_children++;
- list_add_tail(&child->guc_child_link,
&parent->guc_child_list);- child->parent = parent;
+}
#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST) #include "selftest_context.c" #endif diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h index c41098950746..ad6ce5ac4824 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.h +++ b/drivers/gpu/drm/i915/gt/intel_context.h @@ -44,6 +44,24 @@ void intel_context_free(struct intel_context *ce); int intel_context_reconfigure_sseu(struct intel_context *ce, const struct intel_sseu sseu);
+static inline bool intel_context_is_child(struct intel_context *ce) +{
- return !!ce->parent;
+}
+static inline bool intel_context_is_parent(struct intel_context *ce) +{
- return !!ce->guc_number_children;
+}
+void intel_context_bind_parent_child(struct intel_context *parent,
struct intel_context *child);+#define for_each_child(parent, ce)\
- list_for_each_entry(ce, &(parent)->guc_child_list, guc_child_link)
+#define for_each_child_safe(parent, ce, cn)\
- list_for_each_entry_safe(ce, cn, &(parent)->guc_child_list, guc_child_link)
/**
- intel_context_lock_pinned - Stablises the 'pinned' status of the HW context
- @ce - the context
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h index 2df79ba39867..66b22b370a72 100644 --- a/drivers/gpu/drm/i915/gt/intel_context_types.h +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h @@ -202,6 +202,18 @@ struct intel_context { /* GuC context blocked fence */ struct i915_sw_fence guc_blocked;
- /* Head of children list or link in parent's children list */
Kerneldoc layout would be nice, plus explaining when exactly this is set or the list empty (e.g. guch_child_list is empty if and only if guc_number_children > 0 and parent == NULL).
Also mentionting that these are invariant over the lifetime of the object would be nice.
Finally some words on refcounting (like who holds a reference on whom and how we guarantee that use-after-free doesn't go boom since you have links both ways). It looks like parent holds a reference on the child, so how do you make sure the child looking at the parent doesn't go boom? -Daniel
- union {
struct list_head guc_child_list; /* parent */struct list_head guc_child_link; /* child */- };
- /* Pointer to parent */
- struct intel_context *parent;
- /* Number of children if parent */
- u8 guc_number_children;
Another one: Can we really not afford a int here? The nasty thing about unsigned is that wrap-around is well-defined, which is why gcc won't ever complain about it. Which hides bugs. Same for next patch, which also micro-optimizes a few fields to be tiny.
We generally don't have thousands of contexts hanging around, unless there's a reason (which should be documented) this feels like it's squarely on the wrong side of "don't prematurely optimize".
Ok, int it is.
Matt
-Daniel
- /*
*/
- GuC priority management
-- 2.28.0
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch