[PATCH -next v5 3/3] block, bfq: do not idle if only one group is activated

Yu Kuai
2022-04-28T11:54:36Z

Now that root group is counted into 'num_groups_with_busy_queues',
'num_groups_with_busy_queues > 0' is always true in
bfq_asymmetric_scenario(). Thus change the condition to '> 1'.

On the other hand, this change can enable concurrent sync io if only
one group is activated.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
block/bfq-iosched.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 609b4e894684..142e1ca4600f 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -812,7 +812,7 @@ bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
* much easier to maintain the needed state:
* 1) all active queues have the same weight,
* 2) all active queues belong to the same I/O-priority class,
- * 3) there are no active groups.
+ * 3) there are one active group at most.
* In particular, the last condition is always true if hierarchical
* support or the cgroups interface are not enabled, thus no state
* needs to be maintained in this case.
@@ -844,7 +844,7 @@ static bool bfq_asymmetric_scenario(struct bfq_data *bfqd,

return varied_queue_weights || multiple_classes_busy
#ifdef CONFIG_BFQ_GROUP_IOSCHED
- || bfqd->num_groups_with_busy_queues > 0
+ || bfqd->num_groups_with_busy_queues > 1
#endif
;
}
--
2.31.1