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cfq-iosched: Add comments on update timing of weight
[cascardo/linux.git]
/
block
/
cfq-iosched.c
diff --git
a/block/cfq-iosched.c
b/block/cfq-iosched.c
index
cadc378
..
3f31cf9
100644
(file)
--- a/
block/cfq-iosched.c
+++ b/
block/cfq-iosched.c
@@
-1272,15
+1272,22
@@
__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
rb_insert_color(&cfqg->rb_node, &st->rb);
}
rb_insert_color(&cfqg->rb_node, &st->rb);
}
+/*
+ * This has to be called only on activation of cfqg
+ */
static void
cfq_update_group_weight(struct cfq_group *cfqg)
{
static void
cfq_update_group_weight(struct cfq_group *cfqg)
{
- BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
-
if (cfqg->new_weight) {
cfqg->weight = cfqg->new_weight;
cfqg->new_weight = 0;
}
if (cfqg->new_weight) {
cfqg->weight = cfqg->new_weight;
cfqg->new_weight = 0;
}
+}
+
+static void
+cfq_update_group_leaf_weight(struct cfq_group *cfqg)
+{
+ BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
if (cfqg->new_leaf_weight) {
cfqg->leaf_weight = cfqg->new_leaf_weight;
if (cfqg->new_leaf_weight) {
cfqg->leaf_weight = cfqg->new_leaf_weight;
@@
-1299,7
+1306,12
@@
cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
/* add to the service tree */
BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
/* add to the service tree */
BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
- cfq_update_group_weight(cfqg);
+ /*
+ * Update leaf_weight. We cannot update weight at this point
+ * because cfqg might already have been activated and is
+ * contributing its current weight to the parent's child_weight.
+ */
+ cfq_update_group_leaf_weight(cfqg);
__cfq_group_service_tree_add(st, cfqg);
/*
__cfq_group_service_tree_add(st, cfqg);
/*
@@
-1323,6
+1335,7
@@
cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
*/
while ((parent = cfqg_parent(pos))) {
if (propagate) {
*/
while ((parent = cfqg_parent(pos))) {
if (propagate) {
+ cfq_update_group_weight(pos);
propagate = !parent->nr_active++;
parent->children_weight += pos->weight;
}
propagate = !parent->nr_active++;
parent->children_weight += pos->weight;
}