[PATCH 01/49] cyclic-ids

Chris Wilson chris at chris-wilson.co.uk
Tue Aug 4 21:29:33 UTC 2020


---
 drivers/gpu/drm/i915/gt/intel_engine_types.h |  1 +
 drivers/gpu/drm/i915/gt/intel_lrc.c          | 10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index c400aaa2287b..bfa0199b7a2c 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -330,6 +330,7 @@ struct intel_engine_cs {
 	atomic_t fw_active;
 
 	unsigned long context_tag;
+	unsigned long context_last;
 
 	struct rb_node uabi_node;
 
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 417f6b0c6c61..e53a5c8af7b0 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1355,7 +1355,15 @@ __execlists_schedule_in(struct i915_request *rq)
 		ce->lrc.ccid = ce->tag;
 	} else {
 		/* We don't need a strict matching tag, just different values */
-		unsigned int tag = ffs(READ_ONCE(engine->context_tag));
+		unsigned int tag;
+
+		/* Cyclically allocate unused ids */
+		tag = GENMASK(BITS_PER_LONG - 1,
+			      engine->context_last++ % BITS_PER_LONG);
+
+		tag = ffs(READ_ONCE(engine->context_tag) & tag);
+		if (tag == 0)
+			tag = ffs(READ_ONCE(engine->context_tag));
 
 		GEM_BUG_ON(tag == 0 || tag >= BITS_PER_LONG);
 		clear_bit(tag - 1, &engine->context_tag);
-- 
2.20.1



More information about the Intel-gfx-trybot mailing list