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 v2 4/4] block, bfq: consider request size in bfq_asymmetric_scenario()
Date: Fri, 6 Aug 2021 10:08:26 +0800 [thread overview]
Message-ID: <20210806020826.1407257-5-yukuai3@huawei.com> (raw)
In-Reply-To: <20210806020826.1407257-1-yukuai3@huawei.com>
There is a special case when bfq do not need to idle when more than
one groups is active:
1) all active queues have the same weight,
2) all active queues have the same request size.
3) all active queues belong to the same I/O-priority class,
Each time a request is dispatched, bfq can switch in service queue
safely, since the throughput of each active queue is guaranteed to
be equivalent.
Test procedure:
run "fio -numjobs=1 -ioengine=psync -bs=4k -direct=1 -rw=randread..." in
different cgroup(not root).
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) |
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
block/bfq-iosched.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 7df3fc0ef4ef..e5a07bd1fd84 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -268,6 +268,16 @@ static struct kmem_cache *bfq_pool;
*/
#define BFQ_RATE_SHIFT 16
+/*
+ * 1) bfq keep dispatching requests with same size for at least one second.
+ * 2) bfq dispatch at lease 1024 requests
+ *
+ * We think bfq are dispatching request with same size if the above two
+ * conditions hold true.
+ */
+#define VARIED_REQUEST_SIZE(bfqd) ((bfqd)->dispatch_count < 1024 ||\
+ time_before(jiffies, (bfqd)->dispatch_time + HZ))
+
/*
* When configured for computing the duration of the weight-raising
* for interactive queues automatically (see the comments at the
@@ -724,7 +734,8 @@ static bool bfq_asymmetric_scenario(struct bfq_data *bfqd,
bool multiple_classes_busy;
#ifdef CONFIG_BFQ_GROUP_IOSCHED
- if (bfqd->num_groups_with_pending_reqs > 1)
+ if (bfqd->num_groups_with_pending_reqs > 1 &&
+ VARIED_REQUEST_SIZE(bfqd))
return true;
if (bfqd->num_groups_with_pending_reqs &&
--
2.31.1
next prev parent reply other threads:[~2021-08-06 1:57 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-06 2:08 [PATCH v2 0/4] optimize the bfq queue idle judgment Yu Kuai
2021-08-06 2:08 ` [PATCH v2 1/4] block, bfq: add support to track if root_group have any pending requests Yu Kuai
2021-08-26 17:00 ` Paolo Valente
2021-09-02 13:23 ` yukuai (C)
2021-08-06 2:08 ` [PATCH v2 2/4] block, bfq: do not idle if only one cgroup is activated Yu Kuai
2021-08-26 17:00 ` Paolo Valente
2021-09-02 13:31 ` yukuai (C)
2021-09-07 9:10 ` Paolo Valente
2021-09-07 11:19 ` yukuai (C)
2021-08-06 2:08 ` [PATCH v2 3/4] block, bfq: add support to record request size information Yu Kuai
2021-08-26 17:00 ` Paolo Valente
2021-08-06 2:08 ` Yu Kuai [this message]
2021-08-26 17:00 ` [PATCH v2 4/4] block, bfq: consider request size in bfq_asymmetric_scenario() Paolo Valente
2021-09-07 11:29 ` yukuai (C)
2021-09-15 7:36 ` Paolo Valente
2021-09-15 7:47 ` yukuai (C)
2021-08-14 2:34 ` [PATCH v2 0/4] optimize the bfq queue idle judgment yukuai (C)
2021-08-24 14:09 ` yukuai (C)
2021-08-26 16:59 ` Paolo Valente
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