From: Yu Kuai <yukuai3@huawei.com>
To: <paolo.valente@linaro.org>, <axboe@kernel.dk>
Cc: <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<yukuai3@huawei.com>, <yi.zhang@huawei.com>
Subject: [PATCH v3 2/2] block, bfq: do not idle if only one cgroup is activated
Date: Wed, 13 Oct 2021 19:25:34 +0800 [thread overview]
Message-ID: <20211013112534.3073296-3-yukuai3@huawei.com> (raw)
In-Reply-To: <20211013112534.3073296-1-yukuai3@huawei.com>
If only one group is activated, there is no need to guarantee the
same share of the throughput of queues in the same group.
Test procedure:
run "fio -numjobs=1 -ioengine=psync -bs=4k -direct=1 -rw=randread..."
multiple times in the same cgroup.
Test result: total bandwidth(Mib/s)
| total jobs | before this patch | after this patch |
| ---------- | ----------------- | --------------------- |
| 1 | 33.8 | 33.8 |
| 2 | 33.8 | 65.4 (32.7 each job) |
| 4 | 33.8 | 106.8 (26.7 each job) |
| 8 | 33.8 | 126.4 (15.8 each job) |
By the way, if I test with "fio -numjobs=1/2/4/8 ...", test result is
the same with or without this patch. This is because bfq_queue can
be merged in this situation.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
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 d251735383f7..8d94f511bee8 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -709,7 +709,7 @@ 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.
@@ -741,7 +741,7 @@ 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_pending_reqs > 0
+ || bfqd->num_groups_with_pending_reqs > 1
#endif
;
}
--
2.31.1
prev parent reply other threads:[~2021-10-13 11:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-13 11:25 [PATCH v3 0/2] optimize the bfq queue idle judgment Yu Kuai
2021-10-13 11:25 ` [PATCH v3 1/2] block, bfq: counted root group into 'num_groups_with_pending_reqs' Yu Kuai
2021-10-13 16:51 ` kernel test robot
2021-10-13 19:52 ` kernel test robot
2021-10-13 11:25 ` Yu Kuai [this message]
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