gpu: ion: optimize system heap for non fault buffers

If a buffer's user mappings are not going to be faulted
in it need not be allocated page wise.  We can optimize
this common case by allocating an sglist of larger chunks
rather than creating an entry for each page in the
allocation.

Change-Id: I47814990e55c7bdb7abeaa2af824744b0a97602d
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>

1 files changed, 30 insertions, 10 deletions

diff --git a/drivers/gpu/ion/ion_system_heap.c b/drivers/gpu/ion/ion_system_heap.c
index ca6de04f6c2..310c4f66cfa 100644
--- a/drivers/gpu/ion/ion_system_heap.c
+++ b/drivers/gpu/ion/ion_system_heap.c
@@ -31,7 +31,8 @@ struct page_info {
 	struct list_head list;
 };
 
-static struct page_info *alloc_largest_available(unsigned long size)
+static struct page_info *alloc_largest_available(unsigned long size,
+						 bool split_pages)
 {
 	static unsigned int orders[] = {8, 4, 0};
 	struct page *page;
@@ -45,7 +46,8 @@ static struct page_info *alloc_largest_available(unsigned long size)
 				   __GFP_NOWARN | __GFP_NORETRY, orders[i]);
 		if (!page)
 			continue;
-		split_page(page, orders[i]);
+		if (split_pages)
+			split_page(page, orders[i]);
 		info = kmalloc(sizeof(struct page_info *), GFP_KERNEL);
 		info->page = page;
 		info->order = orders[i];
@@ -64,35 +66,49 @@ static int ion_system_heap_allocate(struct ion_heap *heap,
 	int ret;
 	struct list_head pages;
 	struct page_info *info, *tmp_info;
-	int i;
+	int i = 0;
 	long size_remaining = PAGE_ALIGN(size);
+	bool split_pages = ion_buffer_fault_user_mappings(buffer);
+
 
 	INIT_LIST_HEAD(&pages);
 	while (size_remaining > 0) {
-		info = alloc_largest_available(size_remaining);
+		info = alloc_largest_available(size_remaining, split_pages);
 		if (!info)
 			goto err;
 		list_add_tail(&info->list, &pages);
 		size_remaining -= (1 << info->order) * PAGE_SIZE;
+		i++;
 	}
 
 	table = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
 	if (!table)
 		goto err;
 
-	ret = sg_alloc_table(table, PAGE_ALIGN(size) / PAGE_SIZE, GFP_KERNEL);
+	if (split_pages)
+		ret = sg_alloc_table(table, PAGE_ALIGN(size) / PAGE_SIZE,
+				     GFP_KERNEL);
+	else
+		ret = sg_alloc_table(table, i, GFP_KERNEL);
+
 	if (ret)
 		goto err1;
 
 	sg = table->sgl;
 	list_for_each_entry_safe(info, tmp_info, &pages, list) {
 		struct page *page = info->page;
-		for (i = 0; i < (1 << info->order); i++) {
-			sg_set_page(sg, page + i, PAGE_SIZE, 0);
+
+		if (split_pages) {
+			for (i = 0; i < (1 << info->order); i++) {
+				sg_set_page(sg, page + i, PAGE_SIZE, 0);
+				sg = sg_next(sg);
+			}
+		} else {
+			sg_set_page(sg, page, (1 << info->order) * PAGE_SIZE,
+				    0);
 			sg = sg_next(sg);
 		}
 		list_del(&info->list);
-		memset(info, 0, sizeof(struct page_info));
 		kfree(info);
 	}
 
@@ -105,8 +121,12 @@ err1:
 	kfree(table);
 err:
 	list_for_each_entry(info, &pages, list) {
-		for (i = 0; i < (1 << info->order); i++)
-			__free_page(info->page + i);
+		if (split_pages)
+			for (i = 0; i < (1 << info->order); i++)
+				__free_page(info->page + i);
+		else
+			__free_pages(info->page, info->order);
+
 		kfree(info);
 	}
 	return -ENOMEM;