[Intel-gfx] [PATCH v2] drm/i915/pmu: Reconstruct active state on starting busy-stats

[Chris Wilson]

We have a hole in our busy-stat accounting if the pmu is enabled during
a long running batch, the pmu will not start accumulating busy-time
until the next context switch. This then fails tests that are only
sampling a single batch.

v2: Count each active port just once (context in/out events are only on
the first and last assigment to a port).

Testcase: igt/perf_pmu/busy-start
Testcase: igt/perf_pmu/busy-double-start
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/intel_engine_cs.c  | 10 +++++++++-
 drivers/gpu/drm/i915/intel_ringbuffer.h |  2 +-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 6bb51a502b8b..3a11602e60c7 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1951,8 +1951,16 @@ int intel_enable_engine_stats(struct intel_engine_cs *engine)
 	spin_lock_irqsave(&engine->stats.lock, flags);
 	if (engine->stats.enabled == ~0)
 		goto busy;
-	if (engine->stats.enabled++ == 0)
+	if (engine->stats.enabled++ == 0) {
 		engine->stats.enabled_at = ktime_get();
+
+		/* XXX submission method oblivious? */
+		engine->stats.active =
+			port_isset(&engine->execlists.port[1]) +
+			port_isset(&engine->execlists.port[0]);
+		if (engine->stats.active)
+			engine->stats.start = engine->stats.enabled_at;
+	}
 	spin_unlock_irqrestore(&engine->stats.lock, flags);
 
 	return 0;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index c5ff203e42d6..37cf665692e5 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -225,7 +225,7 @@ struct intel_engine_execlists {
 #define port_pack(rq, count) ptr_pack_bits(rq, count, EXECLIST_COUNT_BITS)
 #define port_unpack(p, count) ptr_unpack_bits((p)->request_count, count, EXECLIST_COUNT_BITS)
 #define port_set(p, packed) ((p)->request_count = (packed))
-#define port_isset(p) ((p)->request_count)
+#define port_isset(p) (((p)->request_count) != NULL)
 #define port_index(p, execlists) ((p) - (execlists)->port)
 
 		/**
-- 
2.15.1