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authorChris Mason <chris.mason@oracle.com>2008-09-29 15:18:18 -0400
committerChris Mason <chris.mason@oracle.com>2008-09-29 15:18:18 -0400
commitd352ac68148b69937d39ca5d48bcc4478e118dbf (patch)
tree7951dd7311999d9e77766acdc7f8e93de97874d8 /fs/btrfs/async-thread.c
parent9a5e1ea1e1e539e244a54afffc330fc368376ab9 (diff)
downloadlinux-d352ac68148b69937d39ca5d48bcc4478e118dbf.tar.bz2
Btrfs: add and improve comments
This improves the comments at the top of many functions. It didn't dive into the guts of functions because I was trying to avoid merging problems with the new allocator and back reference work. extent-tree.c and volumes.c were both skipped, and there is definitely more work todo in cleaning and commenting the code. Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/async-thread.c')
-rw-r--r--fs/btrfs/async-thread.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index 4e780b279de6..04fb9702d14c 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -231,17 +231,25 @@ static struct btrfs_worker_thread *next_worker(struct btrfs_workers *workers)
/*
* if we pick a busy task, move the task to the end of the list.
- * hopefully this will keep things somewhat evenly balanced
+ * hopefully this will keep things somewhat evenly balanced.
+ * Do the move in batches based on the sequence number. This groups
+ * requests submitted at roughly the same time onto the same worker.
*/
next = workers->worker_list.next;
worker = list_entry(next, struct btrfs_worker_thread, worker_list);
atomic_inc(&worker->num_pending);
worker->sequence++;
+
if (worker->sequence % workers->idle_thresh == 0)
list_move_tail(next, &workers->worker_list);
return worker;
}
+/*
+ * selects a worker thread to take the next job. This will either find
+ * an idle worker, start a new worker up to the max count, or just return
+ * one of the existing busy workers.
+ */
static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers)
{
struct btrfs_worker_thread *worker;