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authorToshiaki Makita <makita.toshiaki@lab.ntt.co.jp>2014-08-28 17:14:58 +0900
committerJens Axboe <axboe@fb.com>2014-08-28 08:16:29 -0600
commit7b5af5cffce569298b1d03af1ddf1dc43570ab42 (patch)
tree5dde60d7c4ff816ffd8cb2c48207f7d770718ef8
parente15693ef18e13e3e6bffe891fe140f18b8ff6d07 (diff)
downloadlinux-stericsson-7b5af5cffce569298b1d03af1ddf1dc43570ab42.tar.gz
cfq-iosched: Add comments on update timing of weight
Explain that weight has to be updated on activation. This complements previous fix e15693ef18e1 ("cfq-iosched: Fix wrong children_weight calculation"). Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r--block/cfq-iosched.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index d7494637c5db..3f31cf9508e6 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1272,6 +1272,9 @@ __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
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)
{
@@ -1303,6 +1306,11 @@ 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));
+ /*
+ * 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);