[PATCH 1/4] cfq-iosched: Don't group_idle if cfqq has big thinktime

From: Jan Kara
Date: Wed Nov 25 2015 - 09:23:05 EST


From: Jan Kara <jack@xxxxxxxx>

There is no point in idling on a cfq group if the only cfq queue that is
there has too big thinktime.

Signed-off-by: Jan Kara <jack@xxxxxxxx>
---
block/cfq-iosched.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 1f9093e901da..fcef1786edf3 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2897,6 +2897,7 @@ 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 +2948,13 @@ 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);
--
2.1.4

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