Btrfs: Change the congestion functions to meter the number of async submits as well
The async submit workqueue was absorbing too many requests, leading to long
stalls where the async submitters were stalling.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 264f297..3733743 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -453,6 +453,7 @@
spin_lock(&fs_info->async_submit_work_lock);
list_add_tail(&async->list, &fs_info->async_submit_work_list);
+ atomic_inc(&fs_info->nr_async_submits);
spin_unlock(&fs_info->async_submit_work_lock);
queue_work(async_submit_workqueue, &fs_info->async_submit_work);
@@ -906,10 +907,16 @@
{
struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;
int ret = 0;
+ int limit = 256 * info->fs_devices->open_devices;
struct list_head *cur;
struct btrfs_device *device;
struct backing_dev_info *bdi;
+ if ((bdi_bits & (1 << BDI_write_congested)) &&
+ atomic_read(&info->nr_async_submits) > limit) {
+ return 1;
+ }
+
list_for_each(cur, &info->fs_devices->devices) {
device = list_entry(cur, struct btrfs_device, dev_list);
if (!device->bdev)
@@ -1117,6 +1124,7 @@
}
next = fs_info->async_submit_work_list.next;
list_del(next);
+ atomic_dec(&fs_info->nr_async_submits);
spin_unlock(&fs_info->async_submit_work_lock);
async = list_entry(next, struct async_submit_bio, list);
@@ -1179,6 +1187,7 @@
INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
INIT_LIST_HEAD(&fs_info->space_info);
btrfs_mapping_init(&fs_info->mapping_tree);
+ atomic_set(&fs_info->nr_async_submits, 0);
fs_info->sb = sb;
fs_info->max_extent = (u64)-1;
fs_info->max_inline = 8192 * 1024;
