[PATCH 16/31] blk-throttle: add throtl_grp->service_queue

From: Tejun Heo
Date: Wed May 01 2013 - 20:46:01 EST


Currently, there's single service_queue per queue -
throtl_data->service_queue. All active throtl_grp's are queued on the
queue and dispatched according to their limits. To support hierarchy,
this will be expanded such that active throtl_grp's form a tree
anchored at throtl_data->service_queue and chained through each
intermediate throtl_grp's service_queue.

This patch adds throtl_grp->service_queue to prepare for hierarchy
support. The initialization function - throtl_service_queue_init() -
is added and replaces the macro initializer. The newly added
tg->service_queue isn't used yet. Following patches will do.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
block/blk-throttle.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 56b5e2a..ee615af 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -33,9 +33,6 @@ struct throtl_service_queue {
unsigned long first_pending_disptime; /* disptime of the first tg */
};

-#define THROTL_SERVICE_QUEUE_INITIALIZER \
- (struct throtl_service_queue){ .pending_tree = RB_ROOT }
-
enum tg_state_flags {
THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */
};
@@ -60,6 +57,9 @@ struct throtl_grp {
/* throtl_data this group belongs to */
struct throtl_data *td;

+ /* this group's service queue */
+ struct throtl_service_queue service_queue;
+
/*
* Dispatch time in jiffies. This is the estimated time when group
* will unthrottle and is ready to dispatch more bio. It is used as
@@ -190,11 +190,18 @@ alloc_stats:
goto alloc_stats;
}

+/* init a service_queue, assumes the caller zeroed it */
+static void throtl_service_queue_init(struct throtl_service_queue *sq)
+{
+ sq->pending_tree = RB_ROOT;
+}
+
static void throtl_pd_init(struct blkcg_gq *blkg)
{
struct throtl_grp *tg = blkg_to_tg(blkg);
unsigned long flags;

+ throtl_service_queue_init(&tg->service_queue);
RB_CLEAR_NODE(&tg->rb_node);
tg->td = blkg->q->td;
bio_list_init(&tg->bio_lists[0]);
@@ -1171,8 +1178,8 @@ int blk_throtl_init(struct request_queue *q)
if (!td)
return -ENOMEM;

- td->service_queue = THROTL_SERVICE_QUEUE_INITIALIZER;
INIT_DELAYED_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);
+ throtl_service_queue_init(&td->service_queue);

q->td = td;
td->queue = q;
--
1.8.1.4

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