drm/i915: Release the active tracker tree upon idling

As soon as we detect that the active tracker is idle and we prepare to
call the retire callback, release the storage for our tree of
per-timeline nodes. We expect these to be infrequently used and quick
to allocate, so there is little benefit in keeping the tree cached and
we would prefer to return the pages back to the system in a timely
fashion.

This also means that when we finalize the struct as a whole, we know as
the activity tracker must be idle, the tree has already been released.
Indeed we can reduce i915_active_fini() just to the assertions that there
is nothing to do.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190205130005.2807-3-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index 91950d778cab6b52925439eb90219988267d0b6e..b1fefe98f9a6a4d45542f42e0f441723128722f3 100644 (file)
--- a/drivers/gpu/drm/i915/i915_active.c
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -16,12 +16,29 @@ struct active_node {
        u64 timeline;
 };
 
+static void
+__active_park(struct i915_active *ref)
+{
+       struct active_node *it, *n;
+
+       rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
+               GEM_BUG_ON(i915_gem_active_isset(&it->base));
+               kfree(it);
+       }
+       ref->tree = RB_ROOT;
+}
+
 static void
 __active_retire(struct i915_active *ref)
 {
        GEM_BUG_ON(!ref->count);
-       if (!--ref->count)
-               ref->retire(ref);
+       if (--ref->count)
+               return;
+
+       /* return the unused nodes to our slabcache */
+       __active_park(ref);
+
+       ref->retire(ref);
 }
 
 static void
@@ -210,18 +227,14 @@ int i915_request_await_active(struct i915_request *rq, struct i915_active *ref)
        return 0;
 }
 
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
 void i915_active_fini(struct i915_active *ref)
 {
-       struct active_node *it, *n;
-
        GEM_BUG_ON(i915_gem_active_isset(&ref->last));
-
-       rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
-               GEM_BUG_ON(i915_gem_active_isset(&it->base));
-               kfree(it);
-       }
-       ref->tree = RB_ROOT;
+       GEM_BUG_ON(!RB_EMPTY_ROOT(&ref->tree));
+       GEM_BUG_ON(ref->count);
 }
+#endif
 
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/i915_active.c"

diff --git a/drivers/gpu/drm/i915/i915_active.h b/drivers/gpu/drm/i915/i915_active.h
index 0aa2628ea734f78a802164f0c7514fb16a399ebe..ec4b66efd9a7444fe01136737f2097cd145f9611 100644 (file)
--- a/drivers/gpu/drm/i915/i915_active.h
+++ b/drivers/gpu/drm/i915/i915_active.h
@@ -64,6 +64,10 @@ i915_active_is_idle(const struct i915_active *ref)
        return !ref->count;
 }
 
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
 void i915_active_fini(struct i915_active *ref);
+#else
+static inline void i915_active_fini(struct i915_active *ref) { }
+#endif
 
 #endif /* _I915_ACTIVE_H_ */