1 files changed, 135 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_globals.c b/drivers/gpu/drm/i915/i915_globals.c
new file mode 100644
index 000000000000..2f5c72e2a9d1
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_globals.c
@@ -0,0 +1,135 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2019 Intel Corporation
+ */
+
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+#include "i915_active.h"
+#include "i915_gem_context.h"
+#include "i915_gem_object.h"
+#include "i915_globals.h"
+#include "i915_request.h"
+#include "i915_scheduler.h"
+#include "i915_vma.h"
+
+static LIST_HEAD(globals);
+
+void __init i915_global_register(struct i915_global *global)
+{
+	GEM_BUG_ON(!global->shrink);
+	GEM_BUG_ON(!global->exit);
+
+	list_add_tail(&global->link, &globals);
+}
+
+static void __i915_globals_cleanup(void)
+{
+	struct i915_global *global, *next;
+
+	list_for_each_entry_safe_reverse(global, next, &globals, link)
+		global->exit();
+}
+
+static __initconst int (* const initfn[])(void) = {
+	i915_global_active_init,
+	i915_global_context_init,
+	i915_global_gem_context_init,
+	i915_global_objects_init,
+	i915_global_request_init,
+	i915_global_scheduler_init,
+	i915_global_vma_init,
+};
+
+int __init i915_globals_init(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(initfn); i++) {
+		int err;
+
+		err = initfn[i]();
+		if (err) {
+			__i915_globals_cleanup();
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static void i915_globals_shrink(void)
+{
+	struct i915_global *global;
+
+	/*
+	 * kmem_cache_shrink() discards empty slabs and reorders partially
+	 * filled slabs to prioritise allocating from the mostly full slabs,
+	 * with the aim of reducing fragmentation.
+	 */
+	list_for_each_entry(global, &globals, link)
+		global->shrink();
+}
+
+static atomic_t active;
+static atomic_t epoch;
+struct park_work {
+	struct rcu_work work;
+	int epoch;
+};
+
+static void __i915_globals_park(struct work_struct *work)
+{
+	struct park_work *wrk = container_of(work, typeof(*wrk), work.work);
+
+	/* Confirm nothing woke up in the last grace period */
+	if (wrk->epoch == atomic_read(&epoch))
+		i915_globals_shrink();
+
+	kfree(wrk);
+}
+
+void i915_globals_park(void)
+{
+	struct park_work *wrk;
+
+	/*
+	 * Defer shrinking the global slab caches (and other work) until
+	 * after a RCU grace period has completed with no activity. This
+	 * is to try and reduce the latency impact on the consumers caused
+	 * by us shrinking the caches the same time as they are trying to
+	 * allocate, with the assumption being that if we idle long enough
+	 * for an RCU grace period to elapse since the last use, it is likely
+	 * to be longer until we need the caches again.
+	 */
+	if (!atomic_dec_and_test(&active))
+		return;
+
+	wrk = kmalloc(sizeof(*wrk), GFP_KERNEL);
+	if (!wrk)
+		return;
+
+	wrk->epoch = atomic_inc_return(&epoch);
+	INIT_RCU_WORK(&wrk->work, __i915_globals_park);
+	queue_rcu_work(system_wq, &wrk->work);
+}
+
+void i915_globals_unpark(void)
+{
+	atomic_inc(&epoch);
+	atomic_inc(&active);
+}
+
+void __exit i915_globals_exit(void)
+{
+	/* Flush any residual park_work */
+	rcu_barrier();
+	flush_scheduled_work();
+
+	__i915_globals_cleanup();
+
+	/* And ensure that our DESTROY_BY_RCU slabs are truly destroyed */
+	rcu_barrier();
+}