[Intel-gfx] [PATCH 10/25] drm/i915/guc: Assign contexts in parent-child relationship consecutive guc_ids

Matthew Brost
2021-10-14T17:46:21Z

Assign contexts in parent-child relationship consecutive guc_ids. This
is accomplished by partitioning guc_id space between ones that need to
be consecutive (1/16 available guc_ids) and ones that do not (15/16 of
available guc_ids). The consecutive search is implemented via the bitmap
API.

This is a precursor to the full GuC multi-lrc implementation but aligns
to how GuC mutli-lrc interface is defined - guc_ids must be consecutive
when using the GuC multi-lrc interface.

v2:
(Daniel Vetter)
- Explicitly state why we assign consecutive guc_ids
v3:
(John Harrison)
- Bring back in spin lock

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
---
drivers/gpu/drm/i915/gt/uc/intel_guc.h | 6 +-
.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 104 ++++++++++++++----
2 files changed, 86 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
index 74f071a0b6d5..4ca197f400ba 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
@@ -82,9 +82,13 @@ struct intel_guc {
*/
spinlock_t lock;
/**
- * @guc_ids: used to allocate new guc_ids
+ * @guc_ids: used to allocate new guc_ids, single-lrc
*/
struct ida guc_ids;
+ /**
+ * @guc_ids_bitmap: used to allocate new guc_ids, multi-lrc
+ */
+ unsigned long *guc_ids_bitmap;
/**
* @guc_id_list: list of intel_context with valid guc_ids but no
* refs
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index fbcf2dc2b2de..7ba4f1d6f69c 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -128,6 +128,16 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count);

#define GUC_REQUEST_SIZE 64 /* bytes */

+/*
+ * We reserve 1/16 of the guc_ids for multi-lrc as these need to be contiguous
+ * per the GuC submission interface. A different allocation algorithm is used
+ * (bitmap vs. ida) between multi-lrc and single-lrc hence the reason to
+ * partition the guc_id space. We believe the number of multi-lrc contexts in
+ * use should be low and 1/16 should be sufficient. Minimum of 32 guc_ids for
+ * multi-lrc.
+ */
+#define NUMBER_MULTI_LRC_GUC_ID (GUC_MAX_LRC_DESCRIPTORS / 16)
+
/*
* Below is a set of functions which control the GuC scheduling state which
* require a lock.
@@ -1207,6 +1217,11 @@ int intel_guc_submission_init(struct intel_guc *guc)
INIT_WORK(&guc->submission_state.destroyed_worker,
destroyed_worker_func);

+ guc->submission_state.guc_ids_bitmap =
+ bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID, GFP_KERNEL);
+ if (!guc->submission_state.guc_ids_bitmap)
+ return -ENOMEM;
+
return 0;
}

@@ -1218,6 +1233,7 @@ void intel_guc_submission_fini(struct intel_guc *guc)
guc_flush_destroyed_contexts(guc);
guc_lrc_desc_pool_destroy(guc);
i915_sched_engine_put(guc->sched_engine);
+ bitmap_free(guc->submission_state.guc_ids_bitmap);
}

static inline void queue_request(struct i915_sched_engine *sched_engine,
@@ -1269,18 +1285,43 @@ static void guc_submit_request(struct i915_request *rq)
spin_unlock_irqrestore(&sched_engine->lock, flags);
}

-static int new_guc_id(struct intel_guc *guc)
+static int new_guc_id(struct intel_guc *guc, struct intel_context *ce)
{
- return ida_simple_get(&guc->submission_state.guc_ids, 0,
- GUC_MAX_LRC_DESCRIPTORS, GFP_KERNEL |
- __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
+ int ret;
+
+ GEM_BUG_ON(intel_context_is_child(ce));
+
+ if (intel_context_is_parent(ce))
+ ret = bitmap_find_free_region(guc->submission_state.guc_ids_bitmap,
+ NUMBER_MULTI_LRC_GUC_ID,
+ order_base_2(ce->parallel.number_children
+ + 1));
+ else
+ ret = ida_simple_get(&guc->submission_state.guc_ids,
+ NUMBER_MULTI_LRC_GUC_ID,
+ GUC_MAX_LRC_DESCRIPTORS,
+ GFP_KERNEL | __GFP_RETRY_MAYFAIL |
+ __GFP_NOWARN);
+ if (unlikely(ret < 0))
+ return ret;
+
+ ce->guc_id.id = ret;
+ return 0;
}

static void __release_guc_id(struct intel_guc *guc, struct intel_context *ce)
{
+ GEM_BUG_ON(intel_context_is_child(ce));
+
if (!context_guc_id_invalid(ce)) {
- ida_simple_remove(&guc->submission_state.guc_ids,
- ce->guc_id.id);
+ if (intel_context_is_parent(ce))
+ bitmap_release_region(guc->submission_state.guc_ids_bitmap,
+ ce->guc_id.id,
+ order_base_2(ce->parallel.number_children
+ + 1));
+ else
+ ida_simple_remove(&guc->submission_state.guc_ids,
+ ce->guc_id.id);
reset_lrc_desc(guc, ce->guc_id.id);
set_context_guc_id_invalid(ce);
}
@@ -1297,49 +1338,64 @@ static void release_guc_id(struct intel_guc *guc, struct intel_context *ce)
spin_unlock_irqrestore(&guc->submission_state.lock, flags);
}

-static int steal_guc_id(struct intel_guc *guc)
+static int steal_guc_id(struct intel_guc *guc, struct intel_context *ce)
{
- struct intel_context *ce;
- int guc_id;
+ struct intel_context *cn;

lockdep_assert_held(&guc->submission_state.lock);
+ GEM_BUG_ON(intel_context_is_child(ce));
+ GEM_BUG_ON(intel_context_is_parent(ce));

if (!list_empty(&guc->submission_state.guc_id_list)) {
- ce = list_first_entry(&guc->submission_state.guc_id_list,
+ cn = list_first_entry(&guc->submission_state.guc_id_list,
struct intel_context,
guc_id.link);

- GEM_BUG_ON(atomic_read(&ce->guc_id.ref));
- GEM_BUG_ON(context_guc_id_invalid(ce));
+ GEM_BUG_ON(atomic_read(&cn->guc_id.ref));
+ GEM_BUG_ON(context_guc_id_invalid(cn));
+ GEM_BUG_ON(intel_context_is_child(cn));
+ GEM_BUG_ON(intel_context_is_parent(cn));

- list_del_init(&ce->guc_id.link);
- guc_id = ce->guc_id.id;
+ list_del_init(&cn->guc_id.link);
+ ce->guc_id = cn->guc_id;

spin_lock(&ce->guc_state.lock);
- clr_context_registered(ce);
+ clr_context_registered(cn);
spin_unlock(&ce->guc_state.lock);

- set_context_guc_id_invalid(ce);
- return guc_id;
+ set_context_guc_id_invalid(cn);
+
+ return 0;
} else {
return -EAGAIN;
}
}

-static int assign_guc_id(struct intel_guc *guc, u16 *out)
+static int assign_guc_id(struct intel_guc *guc, struct intel_context *ce)
{
int ret;

lockdep_assert_held(&guc->submission_state.lock);
+ GEM_BUG_ON(intel_context_is_child(ce));

- ret = new_guc_id(guc);
+ ret = new_guc_id(guc, ce);
if (unlikely(ret < 0)) {
- ret = steal_guc_id(guc);
+ if (intel_context_is_parent(ce))
+ return -ENOSPC;
+
+ ret = steal_guc_id(guc, ce);
if (ret < 0)
return ret;
}

- *out = ret;
+ if (intel_context_is_parent(ce)) {
+ struct intel_context *child;
+ int i = 1;
+
+ for_each_child(ce, child)
+ child->guc_id.id = ce->guc_id.id + i++;
+ }
+
return 0;
}

@@ -1357,7 +1413,7 @@ static int pin_guc_id(struct intel_guc *guc, struct intel_context *ce)
might_lock(&ce->guc_state.lock);

if (context_guc_id_invalid(ce)) {
- ret = assign_guc_id(guc, &ce->guc_id.id);
+ ret = assign_guc_id(guc, ce);
if (ret)
goto out_unlock;
ret = 1; /* Indidcates newly assigned guc_id */
@@ -1399,8 +1455,10 @@ static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
unsigned long flags;

GEM_BUG_ON(atomic_read(&ce->guc_id.ref) < 0);
+ GEM_BUG_ON(intel_context_is_child(ce));

- if (unlikely(context_guc_id_invalid(ce)))
+ if (unlikely(context_guc_id_invalid(ce) ||
+ intel_context_is_parent(ce)))
return;

spin_lock_irqsave(&guc->submission_state.lock, flags);
--
2.32.0