[Intel-gfx] [PATCH 8/9] drm/i915: Track context current active time

[Chris Wilson <chris@chris-wilson.co.uk>]

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Track context active (on hardware) status together with the start
timestamp.

This will be used to provide better granularity of context
runtime reporting in conjunction with already tracked pphwsp accumulated
runtime.

The latter is only updated on context save so does not give us visibility
to any currently executing work.

As part of the patch the existing runtime tracking data is moved under the
new ce->stats member and updated under the seqlock. This provides the
ability to atomically read out accumulated plus active runtime.

v2:
 * Rename and make __intel_context_get_active_time unlocked.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Aravind Iddamsetty <aravind.iddamsetty@intel.com> #  v1
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c   |  2 +-
 drivers/gpu/drm/i915/gt/intel_context.c       | 10 +++-
 drivers/gpu/drm/i915/gt/intel_context.h       |  6 ++-
 drivers/gpu/drm/i915/gt/intel_context_types.h | 24 ++++++---
 .../drm/i915/gt/intel_execlists_submission.c  |  6 ++-
 drivers/gpu/drm/i915/gt/intel_lrc.c           | 53 +++++++++++++++----
 drivers/gpu/drm/i915/gt/intel_lrc.h           |  3 ++
 drivers/gpu/drm/i915/gt/selftest_lrc.c        | 10 ++--
 drivers/gpu/drm/i915/i915_drm_client.c        |  2 +-
 drivers/gpu/drm/i915/i915_gpu_error.c         |  4 +-
 10 files changed, 87 insertions(+), 33 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 8cf8381e48a5..1a0f96ca7962 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -274,7 +274,7 @@ static void accumulate_runtime(struct i915_drm_client *client,
 		unsigned int class = ce->engine->uabi_class;
 
 		GEM_BUG_ON(class >= ARRAY_SIZE(client->past_runtime));
-		atomic64_add(ce->runtime.total,
+		atomic64_add(ce->stats.runtime.total,
 			     &client->past_runtime[class]);
 	}
 }
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 349e7fa1488d..cb539d3859ff 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -375,7 +375,7 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
 	ce->sseu = engine->sseu;
 	ce->ring = __intel_context_ring_size(SZ_4K);
 
-	ewma_runtime_init(&ce->runtime.avg);
+	ewma_runtime_init(&ce->stats.runtime.avg);
 
 	ce->vm = i915_vm_get(engine->gt->vm);
 
@@ -384,6 +384,7 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
 	INIT_LIST_HEAD(&ce->signals);
 
 	mutex_init(&ce->pin_mutex);
+	seqlock_init(&ce->stats.lock);
 
 	i915_active_init(&ce->active,
 			 __intel_context_active, __intel_context_retire);
@@ -501,6 +502,13 @@ struct i915_request *intel_context_create_request(struct intel_context *ce)
 	return rq;
 }
 
+ktime_t __intel_context_get_active_time(struct intel_context *ce)
+{
+	struct intel_context_stats *stats = &ce->stats;
+
+	return stats->active ? ktime_sub(ktime_get(), stats->start) : 0;
+}
+
 #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 d24ab6fa0ee5..b66078d6a7e9 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -255,14 +255,16 @@ static inline u64 intel_context_get_total_runtime_ns(struct intel_context *ce)
 {
 	const u32 period = ce->engine->gt->clock_period_ns;
 
-	return READ_ONCE(ce->runtime.total) * period;
+	return READ_ONCE(ce->stats.runtime.total) * period;
 }
 
 static inline u64 intel_context_get_avg_runtime_ns(struct intel_context *ce)
 {
 	const u32 period = ce->engine->gt->clock_period_ns;
 
-	return mul_u32_u32(ewma_runtime_read(&ce->runtime.avg), period);
+	return mul_u32_u32(ewma_runtime_read(&ce->stats.runtime.avg), period);
 }
 
+ktime_t __intel_context_get_active_time(struct intel_context *ce);
+
 #endif /* __INTEL_CONTEXT_H__ */
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index e10d78601bbd..0a91cd37c5f0 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -12,6 +12,7 @@
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/types.h>
+#include <linux/seqlock.h>
 
 #include "i915_active_types.h"
 #include "i915_utils.h"
@@ -107,14 +108,21 @@ struct intel_context {
 	} lrc;
 	u32 tag; /* cookie passed to HW to track this context on submission */
 
-	/* Time on GPU as tracked by the hw. */
-	struct {
-		struct ewma_runtime avg;
-		u64 total;
-		u32 last;
-		I915_SELFTEST_DECLARE(u32 num_underflow);
-		I915_SELFTEST_DECLARE(u32 max_underflow);
-	} runtime;
+	/** stats: Context GPU engine busyness tracking. */
+	struct intel_context_stats {
+		seqlock_t lock;
+		bool active;
+		ktime_t start;
+
+		/* Time on GPU as tracked by the hw. */
+		struct {
+			struct ewma_runtime avg;
+			u64 total;
+			u32 last;
+			I915_SELFTEST_DECLARE(u32 num_underflow);
+			I915_SELFTEST_DECLARE(u32 max_underflow);
+		} runtime;
+	} stats;
 
 	unsigned int active_count; /* protected by timeline->mutex */
 
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index 740ff05fd692..4148703596b8 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -609,9 +609,8 @@ static void __execlists_schedule_out(struct i915_request * const rq,
 		GEM_BUG_ON(test_bit(ccid - 1, &engine->context_tag));
 		__set_bit(ccid - 1, &engine->context_tag);
 	}
-
-	lrc_update_runtime(ce);
 	intel_engine_context_out(engine);
+	lrc_runtime_stop(ce);
 	execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT);
 	if (engine->fw_domain && !--engine->fw_active)
 		intel_uncore_forcewake_put(engine->uncore, engine->fw_domain);
@@ -1753,6 +1752,9 @@ static void new_timeslice(struct intel_engine_execlists *el)
 {
 	/* By cancelling, we will start afresh in start_timeslice() */
 	cancel_timer(&el->timer);
+
+	if (*el->active)
+		lrc_runtime_start((*el->active)->context);
 }
 
 static struct i915_request **
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 94f485b591af..2a764de8dd0a 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -640,7 +640,7 @@ static void init_common_regs(u32 * const regs,
 					   CTX_CTRL_RS_CTX_ENABLE);
 	regs[CTX_CONTEXT_CONTROL] = ctl;
 
-	regs[CTX_TIMESTAMP] = ce->runtime.last;
+	regs[CTX_TIMESTAMP] = ce->stats.runtime.last;
 }
 
 static void init_wa_bb_regs(u32 * const regs,
@@ -1532,35 +1532,66 @@ void lrc_init_wa_ctx(struct intel_engine_cs *engine)
 		lrc_fini_wa_ctx(engine);
 }
 
-static void st_update_runtime_underflow(struct intel_context *ce, s32 dt)
+static void st_runtime_underflow(struct intel_context_stats *stats, s32 dt)
 {
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
-	ce->runtime.num_underflow++;
-	ce->runtime.max_underflow = max_t(u32, ce->runtime.max_underflow, -dt);
+	stats->runtime.num_underflow++;
+	stats->runtime.max_underflow =
+		max_t(u32, stats->runtime.max_underflow, -dt);
 #endif
 }
 
 void lrc_update_runtime(struct intel_context *ce)
 {
+	struct intel_context_stats *stats = &ce->stats;
 	u32 old;
 	s32 dt;
 
 	if (intel_context_is_barrier(ce))
 		return;
 
-	old = ce->runtime.last;
-	ce->runtime.last = lrc_get_runtime(ce);
-	dt = ce->runtime.last - old;
+	old = stats->runtime.last;
+	stats->runtime.last = lrc_get_runtime(ce);
+	dt = stats->runtime.last - old;
 
 	if (unlikely(dt < 0)) {
 		CE_TRACE(ce, "runtime underflow: last=%u, new=%u, delta=%d\n",
-			 old, ce->runtime.last, dt);
-		st_update_runtime_underflow(ce, dt);
+			 old, stats->runtime.last, dt);
+		st_runtime_underflow(stats, dt);
 		return;
 	}
 
-	ewma_runtime_add(&ce->runtime.avg, dt);
-	ce->runtime.total += dt;
+	ewma_runtime_add(&stats->runtime.avg, dt);
+	stats->runtime.total += dt;
+}
+
+void lrc_runtime_start(struct intel_context *ce)
+{
+	struct intel_context_stats *stats = &ce->stats;
+	unsigned long flags;
+
+	if (stats->active)
+		return;
+
+	write_seqlock_irqsave(&stats->lock, flags);
+	stats->start = ktime_get();
+	stats->active = true;
+	write_sequnlock_irqrestore(&stats->lock, flags);
+}
+
+void lrc_runtime_stop(struct intel_context *ce)
+{
+	struct intel_context_stats *stats = &ce->stats;
+	unsigned long flags;
+
+	if (!stats->active)
+		return;
+
+	write_seqlock_irqsave(&stats->lock, flags);
+	stats->active = false;
+	stats->start = 0;
+	lrc_update_runtime(ce);
+	write_sequnlock_irqrestore(&stats->lock, flags);
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.h b/drivers/gpu/drm/i915/gt/intel_lrc.h
index 7f697845c4cf..b7a0dafbdf3c 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.h
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.h
@@ -67,6 +67,9 @@ void lrc_check_regs(const struct intel_context *ce,
 		    const struct intel_engine_cs *engine,
 		    const char *when);
 
+void lrc_runtime_start(struct intel_context *ce);
+void lrc_runtime_stop(struct intel_context *ce);
+
 void lrc_update_runtime(struct intel_context *ce);
 static inline u32 lrc_get_runtime(const struct intel_context *ce)
 {
diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c
index 920979a89413..ad0200d0e4c3 100644
--- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
+++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
@@ -1750,8 +1750,8 @@ static int __live_pphwsp_runtime(struct intel_engine_cs *engine)
 	if (IS_ERR(ce))
 		return PTR_ERR(ce);
 
-	ce->runtime.num_underflow = 0;
-	ce->runtime.max_underflow = 0;
+	ce->stats.runtime.num_underflow = 0;
+	ce->stats.runtime.max_underflow = 0;
 
 	do {
 		unsigned int loop = 1024;
@@ -1789,11 +1789,11 @@ static int __live_pphwsp_runtime(struct intel_engine_cs *engine)
 		intel_context_get_avg_runtime_ns(ce));
 
 	err = 0;
-	if (ce->runtime.num_underflow) {
+	if (ce->stats.runtime.num_underflow) {
 		pr_err("%s: pphwsp underflow %u time(s), max %u cycles!\n",
 		       engine->name,
-		       ce->runtime.num_underflow,
-		       ce->runtime.max_underflow);
+		       ce->stats.runtime.num_underflow,
+		       ce->stats.runtime.max_underflow);
 		GEM_TRACE_DUMP();
 		err = -EOVERFLOW;
 	}
diff --git a/drivers/gpu/drm/i915/i915_drm_client.c b/drivers/gpu/drm/i915/i915_drm_client.c
index ce51a02bf33b..5b94d2dcfa4c 100644
--- a/drivers/gpu/drm/i915/i915_drm_client.c
+++ b/drivers/gpu/drm/i915/i915_drm_client.c
@@ -69,7 +69,7 @@ static u64 pphwsp_busy_add(struct i915_gem_context *ctx, unsigned int class)
 
 	for_each_gem_engine(ce, engines, it) {
 		if (ce->engine->uabi_class == class)
-			total += ce->runtime.total;
+			total += ce->stats.runtime.total;
 	}
 
 	return total;
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index b50d8f81830e..6ecf19a64950 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1286,8 +1286,8 @@ static bool record_context(struct i915_gem_context_coredump *e,
 	e->guilty = atomic_read(&ctx->guilty_count);
 	e->active = atomic_read(&ctx->active_count);
 
-	e->total_runtime = rq->context->runtime.total;
-	e->avg_runtime = ewma_runtime_read(&rq->context->runtime.avg);
+	e->total_runtime = rq->context->stats.runtime.total;
+	e->avg_runtime = ewma_runtime_read(&rq->context->stats.runtime.avg);
 
 	simulated = i915_gem_context_no_error_capture(ctx);
 
-- 
2.20.1

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