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-rw-r--r--block/cfq-iosched.c43
1 files changed, 33 insertions, 10 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 1f9093e..e3c591d 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -632,6 +632,13 @@ static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
return pblkg ? blkg_to_cfqg(pblkg) : NULL;
}
+static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
+ struct cfq_group *ancestor)
+{
+ return cgroup_is_descendant(cfqg_to_blkg(cfqg)->blkcg->css.cgroup,
+ cfqg_to_blkg(ancestor)->blkcg->css.cgroup);
+}
+
static inline void cfqg_get(struct cfq_group *cfqg)
{
return blkg_get(cfqg_to_blkg(cfqg));
@@ -758,6 +765,11 @@ static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
#else /* CONFIG_CFQ_GROUP_IOSCHED */
static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
+static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
+ struct cfq_group *ancestor)
+{
+ return true;
+}
static inline void cfqg_get(struct cfq_group *cfqg) { }
static inline void cfqg_put(struct cfq_group *cfqg) { }
@@ -2897,6 +2909,7 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
static void cfq_arm_slice_timer(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq = cfqd->active_queue;
+ struct cfq_rb_root *st = cfqq->service_tree;
struct cfq_io_cq *cic;
unsigned long sl, group_idle = 0;
@@ -2947,8 +2960,13 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
return;
}
- /* There are other queues in the group, don't do group idle */
- if (group_idle && cfqq->cfqg->nr_cfqq > 1)
+ /*
+ * There are other queues in the group or this is the only group and
+ * it has too big thinktime, don't do group idle.
+ */
+ if (group_idle &&
+ (cfqq->cfqg->nr_cfqq > 1 ||
+ cfq_io_thinktime_big(cfqd, &st->ttime, true)))
return;
cfq_mark_cfqq_wait_request(cfqq);
@@ -3947,16 +3965,27 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
return true;
- if (new_cfqq->cfqg != cfqq->cfqg)
+ /*
+ * Treat ancestors of current cgroup the same way as current cgroup.
+ * For anybody else we disallow preemption to guarantee service
+ * fairness among cgroups.
+ */
+ if (!cfqg_is_descendant(cfqq->cfqg, new_cfqq->cfqg))
return false;
if (cfq_slice_used(cfqq))
return true;
+ /*
+ * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
+ */
+ if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
+ return true;
+
+ WARN_ON_ONCE(cfqq->ioprio_class != new_cfqq->ioprio_class);
/* Allow preemption only if we are idling on sync-noidle tree */
if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
- new_cfqq->service_tree->count == 2 &&
RB_EMPTY_ROOT(&cfqq->sort_list))
return true;
@@ -3967,12 +3996,6 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
return true;
- /*
- * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
- */
- if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
- return true;
-
/* An idle queue should not be idle now for some reason */
if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
return true;
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