drm/ttm: Add sysfs interface to control pool allocator.

Sysfs interface allows user to configure pool allocator functionality and
change limits for the size of pool.

Signed-off-by: Pauli Nieminen <suokkos@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/ttm/ttm_memory.c

@@ -393,7 +393,7 @@ int ttm_mem_global_init(struct ttm_mem_global *glob)
 		       "Zone %7s: Available graphics memory: %llu kiB.\n",
 		       zone->name, (unsigned long long) zone->max_mem >> 10);
 	}
-	ttm_page_alloc_init(glob->zone_kernel->max_mem/(2*PAGE_SIZE));
+	ttm_page_alloc_init(glob, glob->zone_kernel->max_mem/(2*PAGE_SIZE));
 	return 0;
 out_no_zone:
 	ttm_mem_global_release(glob);

drivers/gpu/drm/ttm/ttm_page_alloc.c

@@ -72,6 +72,12 @@ struct ttm_page_pool {
 	unsigned long		nrefills;
 };
 
+/**
+ * Limits for the pool. They are handled without locks because only place where
+ * they may change is in sysfs store. They won't have immediate effect anyway
+ * so forcing serialiazation to access them is pointless.
+ */
+
 struct ttm_pool_opts {
 	unsigned	alloc_size;
 	unsigned	max_size;
@@ -94,6 +100,7 @@ struct ttm_pool_opts {
  * @pools: All pool objects in use.
  **/
 struct ttm_pool_manager {
+	struct kobject		kobj;
 	struct shrinker		mm_shrink;
 	atomic_t		page_alloc_inited;
 	struct ttm_pool_opts	options;
@@ -109,6 +116,100 @@ struct ttm_pool_manager {
 	};
 };
 
+static struct attribute ttm_page_pool_max = {
+	.name = "pool_max_size",
+	.mode = S_IRUGO | S_IWUSR
+};
+static struct attribute ttm_page_pool_small = {
+	.name = "pool_small_allocation",
+	.mode = S_IRUGO | S_IWUSR
+};
+static struct attribute ttm_page_pool_alloc_size = {
+	.name = "pool_allocation_size",
+	.mode = S_IRUGO | S_IWUSR
+};
+
+static struct attribute *ttm_pool_attrs[] = {
+	&ttm_page_pool_max,
+	&ttm_page_pool_small,
+	&ttm_page_pool_alloc_size,
+	NULL
+};
+
+static void ttm_pool_kobj_release(struct kobject *kobj)
+{
+	struct ttm_pool_manager *m =
+		container_of(kobj, struct ttm_pool_manager, kobj);
+	(void)m;
+}
+
+static ssize_t ttm_pool_store(struct kobject *kobj,
+		struct attribute *attr, const char *buffer, size_t size)
+{
+	struct ttm_pool_manager *m =
+		container_of(kobj, struct ttm_pool_manager, kobj);
+	int chars;
+	unsigned val;
+	chars = sscanf(buffer, "%u", &val);
+	if (chars == 0)
+		return size;
+
+	/* Convert kb to number of pages */
+	val = val / (PAGE_SIZE >> 10);
+
+	if (attr == &ttm_page_pool_max)
+		m->options.max_size = val;
+	else if (attr == &ttm_page_pool_small)
+		m->options.small = val;
+	else if (attr == &ttm_page_pool_alloc_size) {
+		if (val > NUM_PAGES_TO_ALLOC*8) {
+			printk(KERN_ERR "[ttm] Setting allocation size to %lu "
+					"is not allowed. Recomended size is "
+					"%lu\n",
+					NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 7),
+					NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 10));
+			return size;
+		} else if (val > NUM_PAGES_TO_ALLOC) {
+			printk(KERN_WARNING "[ttm] Setting allocation size to "
+					"larger than %lu is not recomended.\n",
+					NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 10));
+		}
+		m->options.alloc_size = val;
+	}
+
+	return size;
+}
+
+static ssize_t ttm_pool_show(struct kobject *kobj,
+		struct attribute *attr, char *buffer)
+{
+	struct ttm_pool_manager *m =
+		container_of(kobj, struct ttm_pool_manager, kobj);
+	unsigned val = 0;
+
+	if (attr == &ttm_page_pool_max)
+		val = m->options.max_size;
+	else if (attr == &ttm_page_pool_small)
+		val = m->options.small;
+	else if (attr == &ttm_page_pool_alloc_size)
+		val = m->options.alloc_size;
+
+	val = val * (PAGE_SIZE >> 10);
+
+	return snprintf(buffer, PAGE_SIZE, "%u\n", val);
+}
+
+static const struct sysfs_ops ttm_pool_sysfs_ops = {
+	.show = &ttm_pool_show,
+	.store = &ttm_pool_store,
+};
+
+static struct kobj_type ttm_pool_kobj_type = {
+	.release = &ttm_pool_kobj_release,
+	.sysfs_ops = &ttm_pool_sysfs_ops,
+	.default_attrs = ttm_pool_attrs,
+};
+
 static struct ttm_pool_manager _manager = {
 	.page_alloc_inited	= ATOMIC_INIT(0)
 };
@@ -669,8 +770,9 @@ static void ttm_page_pool_init_locked(struct ttm_page_pool *pool, int flags,
 	pool->name = name;
 }
 
-int ttm_page_alloc_init(unsigned max_pages)
+int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages)
 {
+	int ret;
 	if (atomic_add_return(1, &_manager.page_alloc_inited) > 1)
 		return 0;
 
@@ -690,6 +792,13 @@ int ttm_page_alloc_init(unsigned max_pages)
 	_manager.options.small = SMALL_ALLOCATION;
 	_manager.options.alloc_size = NUM_PAGES_TO_ALLOC;
 
+	kobject_init(&_manager.kobj, &ttm_pool_kobj_type);
+	ret = kobject_add(&_manager.kobj, &glob->kobj, "pool");
+	if (unlikely(ret != 0)) {
+		kobject_put(&_manager.kobj);
+		return ret;
+	}
+
 	ttm_pool_mm_shrink_init(&_manager);
 
 	return 0;
@@ -707,6 +816,8 @@ void ttm_page_alloc_fini()
 
 	for (i = 0; i < NUM_POOLS; ++i)
 		ttm_page_pool_free(&_manager.pools[i], FREE_ALL_PAGES);
+
+	kobject_put(&_manager.kobj);
 }
 
 int ttm_page_alloc_debugfs(struct seq_file *m, void *data)

include/drm/ttm/ttm_page_alloc.h

@@ -61,7 +61,7 @@ void ttm_put_pages(struct list_head *pages,
  * multiple times but ttm_page_alloc_fini has to be called same number of
  * times.
  */
-int ttm_page_alloc_init(unsigned max_pages);
+int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages);
 /**
  * Free pool allocator.
  */