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authorTejun Heo <tj@kernel.org>2013-05-15 00:52:38 +0400
committerTejun Heo <tj@kernel.org>2013-05-15 00:52:38 +0400
commit2e48a530a3a7daebd0cc17866304a36d39b611de (patch)
tree6fc47a1a5b74966ff19f5287dc58fbcf3a541ee6
parent6bc9c2b464fb89eab705da87aa4284171d942369 (diff)
downloadlinux-2e48a530a3a7daebd0cc17866304a36d39b611de.tar.xz
blk-throttle: make throtl_pending_timer_fn() ready for hierarchy
throtl_pending_timer_fn() currently assumes that the parent_sq is the top level one and the bio's dispatched are ready to be issued; however, this assumption will be wrong with proper hierarchy support. This patch makes the following changes to make throtl_pending_timer_fn() ready for hiearchy. * If the parent_sq isn't the top-level one, update the parent throtl_grp's dispatch time and schedule the next dispatch as necessary. If the parent's dispatch time is now, repeat the function for the parent throtl_grp. * If the parent_sq is the top-level one, kick issue work_item as before. * The debug message printed by throtl_log() now prints out the service_queue's nr_queued[] instead of the total nr_queued as the latter becomes uninteresting and misleading with hierarchical dispatch. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
-rw-r--r--block/blk-throttle.c40
1 files changed, 33 insertions, 7 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 04202617fda5..bc65077f6e43 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -952,23 +952,33 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq)
* This timer is armed when a child throtl_grp with active bio's become
* pending and queued on the service_queue's pending_tree and expires when
* the first child throtl_grp should be dispatched. This function
- * dispatches bio's from the children throtl_grps and kicks
- * throtl_data->dispatch_work if there are bio's ready to be issued.
+ * dispatches bio's from the children throtl_grps to the parent
+ * service_queue.
+ *
+ * If the parent's parent is another throtl_grp, dispatching is propagated
+ * by either arming its pending_timer or repeating dispatch directly. If
+ * the top-level service_tree is reached, throtl_data->dispatch_work is
+ * kicked so that the ready bio's are issued.
*/
static void throtl_pending_timer_fn(unsigned long arg)
{
struct throtl_service_queue *sq = (void *)arg;
+ struct throtl_grp *tg = sq_to_tg(sq);
struct throtl_data *td = sq_to_td(sq);
struct request_queue *q = td->queue;
- bool dispatched = false;
+ struct throtl_service_queue *parent_sq;
+ bool dispatched;
int ret;
spin_lock_irq(q->queue_lock);
+again:
+ parent_sq = sq->parent_sq;
+ dispatched = false;
while (true) {
throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u",
- td->nr_queued[READ] + td->nr_queued[WRITE],
- td->nr_queued[READ], td->nr_queued[WRITE]);
+ sq->nr_queued[READ] + sq->nr_queued[WRITE],
+ sq->nr_queued[READ], sq->nr_queued[WRITE]);
ret = throtl_select_dispatch(sq);
if (ret) {
@@ -985,9 +995,25 @@ static void throtl_pending_timer_fn(unsigned long arg)
spin_lock_irq(q->queue_lock);
}
- if (dispatched)
- queue_work(kthrotld_workqueue, &td->dispatch_work);
+ if (!dispatched)
+ goto out_unlock;
+ if (parent_sq) {
+ /* @parent_sq is another throl_grp, propagate dispatch */
+ if (tg->flags & THROTL_TG_WAS_EMPTY) {
+ tg_update_disptime(tg);
+ if (!throtl_schedule_next_dispatch(parent_sq, false)) {
+ /* window is already open, repeat dispatching */
+ sq = parent_sq;
+ tg = sq_to_tg(sq);
+ goto again;
+ }
+ }
+ } else {
+ /* reached the top-level, queue issueing */
+ queue_work(kthrotld_workqueue, &td->dispatch_work);
+ }
+out_unlock:
spin_unlock_irq(q->queue_lock);
}