[Intel-gfx] [PATCH 04/46] drm/i915/guc: Don't allow requests not ready to consume all guc_ids

Matthew Brost
2021-08-03T22:12:19Z

Add a heuristic which checks if over half of the available guc_ids are
currently consumed by requests not ready to be submitted. If this
heuristic is true at request creation time (normal guc_id allocation
location) force all submissions + guc_ids allocations to tasklet.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
drivers/gpu/drm/i915/gt/intel_context_types.h | 3 ++
drivers/gpu/drm/i915/gt/intel_reset.c | 9 ++++
drivers/gpu/drm/i915/gt/uc/intel_guc.h | 1 +
.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 53 +++++++++++++++++--
.../gpu/drm/i915/gt/uc/intel_guc_submission.h | 2 +
5 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 8ed964ef967b..c01530d7dc67 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -188,6 +188,9 @@ struct intel_context {
/* Number of rq submitted without a guc_id */
u16 guc_num_rq_submit_no_id;

+ /* GuC number of requests not ready */
+ atomic_t guc_num_rq_not_ready;
+
/*
* GuC ID link - in list when unpinned but guc_id still valid in GuC
*/
diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
index 91200c43951f..ea763138197f 100644
--- a/drivers/gpu/drm/i915/gt/intel_reset.c
+++ b/drivers/gpu/drm/i915/gt/intel_reset.c
@@ -22,6 +22,7 @@
#include "intel_reset.h"

#include "uc/intel_guc.h"
+#include "uc/intel_guc_submission.h"

#define RESET_MAX_RETRIES 3

@@ -850,6 +851,14 @@ static void nop_submit_request(struct i915_request *request)
{
RQ_TRACE(request, "-EIO\n");

+ /*
+ * XXX: Kinda ugly to check for GuC submission here but this function is
+ * going away once we switch to the DRM scheduler so we can live with
+ * this for now.
+ */
+ if (intel_engine_uses_guc(request->engine))
+ intel_guc_decr_num_rq_not_ready(request->context);
+
request = i915_request_mark_eio(request);
if (request) {
i915_request_submit(request);
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
index e76579396efd..917352c9f323 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
@@ -76,6 +76,7 @@ struct intel_guc {
struct ida guc_ids;
u32 num_guc_ids;
u32 max_guc_ids;
+ atomic_t num_guc_ids_not_ready;
struct list_head guc_id_list_no_ref;
struct list_head guc_id_list_unpinned;

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 f42a707f60ca..ba750fc87af1 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1384,6 +1384,41 @@ static inline void queue_request(struct i915_sched_engine *sched_engine,
kick_tasklet(&rq->engine->gt->uc.guc);
}

+/* Macro to tweak heuristic, using a simple over 50% not ready for now */
+#define TOO_MANY_GUC_IDS_NOT_READY(avail, consumed) \
+ ((consumed) > (avail) / 2)
+static bool too_many_guc_ids_not_ready(struct intel_guc *guc,
+ struct intel_context *ce)
+{
+ u32 available_guc_ids, guc_ids_consumed;
+
+ available_guc_ids = guc->num_guc_ids;
+ guc_ids_consumed = atomic_read(&guc->num_guc_ids_not_ready);
+
+ if (TOO_MANY_GUC_IDS_NOT_READY(available_guc_ids, guc_ids_consumed)) {
+ set_and_update_guc_ids_exhausted(guc);
+ return true;
+ }
+
+ return false;
+}
+
+static void incr_num_rq_not_ready(struct intel_context *ce)
+{
+ struct intel_guc *guc = ce_to_guc(ce);
+
+ if (!atomic_fetch_add(1, &ce->guc_num_rq_not_ready))
+ atomic_inc(&guc->num_guc_ids_not_ready);
+}
+
+void intel_guc_decr_num_rq_not_ready(struct intel_context *ce)
+{
+ struct intel_guc *guc = ce_to_guc(ce);
+
+ if (atomic_fetch_add(-1, &ce->guc_num_rq_not_ready) == 1)
+ atomic_dec(&guc->num_guc_ids_not_ready);
+}
+
static bool need_tasklet(struct intel_guc *guc, struct intel_context *ce)
{
struct i915_sched_engine * const sched_engine =
@@ -1430,6 +1465,8 @@ static void guc_submit_request(struct i915_request *rq)
kick_tasklet(guc);

spin_unlock_irqrestore(&sched_engine->lock, flags);
+
+ intel_guc_decr_num_rq_not_ready(rq->context);
}

static int new_guc_id(struct intel_guc *guc)
@@ -2647,10 +2684,13 @@ static int guc_request_alloc(struct i915_request *rq)
rq->reserved_space -= GUC_REQUEST_SIZE;

/*
- * guc_ids are exhausted, don't allocate one here, defer to submission
- * in the tasklet.
+ * guc_ids are exhausted or a heuristic is met indicating too many
+ * guc_ids are waiting on requests with submission dependencies (not
+ * ready to submit). Don't allocate one here, defer to submission in the
+ * tasklet.
*/
- if (test_and_update_guc_ids_exhausted(guc)) {
+ if (test_and_update_guc_ids_exhausted(guc) ||
+ too_many_guc_ids_not_ready(guc, ce)) {
set_bit(I915_FENCE_FLAG_GUC_ID_NOT_PINNED, &rq->fence.flags);
goto out;
}
@@ -2684,6 +2724,7 @@ static int guc_request_alloc(struct i915_request *rq)
*/
set_bit(I915_FENCE_FLAG_GUC_ID_NOT_PINNED, &rq->fence.flags);
set_and_update_guc_ids_exhausted(guc);
+ incr_num_rq_not_ready(ce);

return 0;
} else if (unlikely(ret < 0)) {
@@ -2708,6 +2749,8 @@ static int guc_request_alloc(struct i915_request *rq)
clear_bit(CONTEXT_LRCA_DIRTY, &ce->flags);

out:
+ incr_num_rq_not_ready(ce);
+
/*
* We block all requests on this context if a G2H is pending for a
* schedule disable or context deregistration as the GuC will fail a
@@ -3512,6 +3555,8 @@ void intel_guc_submission_print_info(struct intel_guc *guc,
drm_printf(p, "GuC submit flags: 0x%04lx\n", guc->flags);
drm_printf(p, "GuC total number request without guc_id: %d\n",
guc->total_num_rq_with_no_guc_id);
+ drm_printf(p, "GuC Number GuC IDs not ready: %d\n",
+ atomic_read(&guc->num_guc_ids_not_ready));
drm_printf(p, "GuC stall reason: %d\n", guc->submission_stall_reason);
drm_printf(p, "GuC stalled request: %s\n",
yesno(guc->stalled_rq));
@@ -3567,6 +3612,8 @@ void intel_guc_submission_print_context_info(struct intel_guc *guc,
atomic_read(&ce->pin_count));
drm_printf(p, "\t\tGuC ID Ref Count: %u\n",
atomic_read(&ce->guc_id_ref));
+ drm_printf(p, "\t\tNumber Requests Not Ready: %u\n",
+ atomic_read(&ce->guc_num_rq_not_ready));
drm_printf(p, "\t\tSchedule State: 0x%x, 0x%x\n\n",
ce->guc_state.sched_state,
atomic_read(&ce->guc_sched_state_no_lock));
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.h
index c7ef44fa0c36..17af5e123b09 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.h
@@ -51,4 +51,6 @@ static inline bool intel_guc_submission_is_used(struct intel_guc *guc)
return intel_guc_is_used(guc) && intel_guc_submission_is_wanted(guc);
}

+void intel_guc_decr_num_rq_not_ready(struct intel_context *ce);
+
#endif
--
2.28.0