From: Changheun Lee <nanich.lee@samsung.com>
To: Johannes.Thumshirn@wdc.com, asml.silence@gmail.com,
axboe@kernel.dk, damien.lemoal@wdc.com,
gregkh@linuxfoundation.org, hch@infradead.org,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
ming.lei@redhat.com, osandov@fb.com, patchwork-bot@kernel.org,
tj@kernel.org, tom.leiming@gmail.com
Cc: jisoo2146.oh@samsung.com, junho89.kim@samsung.com,
mj0123.lee@samsung.com, seunghwan.hyun@samsung.com,
sookwan7.kim@samsung.com, woosung2.lee@samsung.com,
yt0928.kim@samsung.com, Changheun Lee <nanich.lee@samsung.com>
Subject: [RESEND PATCH v5 1/2] bio: limit bio max size
Date: Tue, 16 Mar 2021 16:44:00 +0900 [thread overview]
Message-ID: <20210316074401.4594-1-nanich.lee@samsung.com> (raw)
In-Reply-To: CGME20210316080104epcas1p11483035c927c2e65600ae90309334b24@epcas1p1.samsung.com
bio size can grow up to 4GB when muli-page bvec is enabled.
but sometimes it would lead to inefficient behaviors.
in case of large chunk direct I/O, - 32MB chunk read in user space -
all pages for 32MB would be merged to a bio structure if the pages
physical addresses are contiguous. it makes some delay to submit
until merge complete. bio max size should be limited to a proper size.
When 32MB chunk read with direct I/O option is coming from userspace,
kernel behavior is below now in do_direct_IO() loop. it's timeline.
| bio merge for 32MB. total 8,192 pages are merged.
| total elapsed time is over 2ms.
|------------------ ... ----------------------->|
| 8,192 pages merged a bio.
| at this time, first bio submit is done.
| 1 bio is split to 32 read request and issue.
|--------------->
|--------------->
|--------------->
......
|--------------->
|--------------->|
total 19ms elapsed to complete 32MB read done from device. |
If bio max size is limited with 1MB, behavior is changed below.
| bio merge for 1MB. 256 pages are merged for each bio.
| total 32 bio will be made.
| total elapsed time is over 2ms. it's same.
| but, first bio submit timing is fast. about 100us.
|--->|--->|--->|---> ... -->|--->|--->|--->|--->|
| 256 pages merged a bio.
| at this time, first bio submit is done.
| and 1 read request is issued for 1 bio.
|--------------->
|--------------->
|--------------->
......
|--------------->
|--------------->|
total 17ms elapsed to complete 32MB read done from device. |
As a result, read request issue timing is faster if bio max size is limited.
Current kernel behavior with multipage bvec, super large bio can be created.
And it lead to delay first I/O request issue.
Signed-off-by: Changheun Lee <nanich.lee@samsung.com>
---
block/bio.c | 13 ++++++++++++-
include/linux/bio.h | 2 +-
include/linux/blkdev.h | 3 +++
3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 1f2cc1fbe283..c528e1f944c7 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -287,6 +287,17 @@ void bio_init(struct bio *bio, struct bio_vec *table,
}
EXPORT_SYMBOL(bio_init);
+unsigned int bio_max_size(struct bio *bio)
+{
+ struct request_queue *q = bio->bi_disk->queue;
+
+ if (blk_queue_limit_bio_size(q))
+ return blk_queue_get_max_sectors(q, bio_op(bio))
+ << SECTOR_SHIFT;
+
+ return UINT_MAX;
+}
+
/**
* bio_reset - reinitialize a bio
* @bio: bio to reset
@@ -877,7 +888,7 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page,
struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (page_is_mergeable(bv, page, len, off, same_page)) {
- if (bio->bi_iter.bi_size > UINT_MAX - len) {
+ if (bio->bi_iter.bi_size > bio_max_size(bio) - len) {
*same_page = false;
return false;
}
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 1edda614f7ce..13b6f6562a5b 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -113,7 +113,7 @@ static inline bool bio_full(struct bio *bio, unsigned len)
if (bio->bi_vcnt >= bio->bi_max_vecs)
return true;
- if (bio->bi_iter.bi_size > UINT_MAX - len)
+ if (bio->bi_iter.bi_size > bio_max_size(bio) - len)
return true;
return false;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f94ee3089e01..3aeab9e7e97b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -621,6 +621,7 @@ struct request_queue {
#define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */
#define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */
#define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */
+#define QUEUE_FLAG_LIMIT_BIO_SIZE 30 /* limit bio size */
#define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_SAME_COMP) | \
@@ -667,6 +668,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
#define blk_queue_fua(q) test_bit(QUEUE_FLAG_FUA, &(q)->queue_flags)
#define blk_queue_registered(q) test_bit(QUEUE_FLAG_REGISTERED, &(q)->queue_flags)
#define blk_queue_nowait(q) test_bit(QUEUE_FLAG_NOWAIT, &(q)->queue_flags)
+#define blk_queue_limit_bio_size(q) \
+ test_bit(QUEUE_FLAG_LIMIT_BIO_SIZE, &(q)->queue_flags)
extern void blk_set_pm_only(struct request_queue *q);
extern void blk_clear_pm_only(struct request_queue *q);
--
2.28.0
next parent reply other threads:[~2021-03-16 8:02 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20210316080104epcas1p11483035c927c2e65600ae90309334b24@epcas1p1.samsung.com>
2021-03-16 7:44 ` Changheun Lee [this message]
[not found] ` <CGME20210316080106epcas1p3522dda95e9c97fc39b40b008bbf87c04@epcas1p3.samsung.com>
2021-03-16 7:44 ` [RESEND PATCH v5 2/2] bio: add limit_bio_size sysfs Changheun Lee
2021-04-06 21:05 ` Bart Van Assche
[not found] ` <CGME20210407013850epcas1p2d305f138c9fa1431abba1ec44a382de9@epcas1p2.samsung.com>
2021-04-07 1:21 ` Changheun Lee
2021-04-07 5:43 ` Greg KH
[not found] ` <CGME20210406014905epcas1p16830a46b7ac6af95a0e2c2c6f4c04859@epcas1p1.samsung.com>
2021-04-06 1:31 ` [RESEND PATCH v5 1/2] bio: limit bio max size Changheun Lee
2021-04-06 7:32 ` Greg KH
[not found] ` <CGME20210407003345epcas1p21376df37d3dfe933684139d3beaf9c51@epcas1p2.samsung.com>
2021-04-07 0:16 ` Changheun Lee
2021-04-07 5:05 ` Greg KH
[not found] ` <CGME20210407052407epcas1p1d0b5d23ac04a68760f691954e7ada3dd@epcas1p1.samsung.com>
2021-04-07 5:06 ` Changheun Lee
2021-04-07 5:36 ` Greg KH
[not found] ` <CGME20210407071241epcas1p2559ea674299b686c9001326894c933bc@epcas1p2.samsung.com>
2021-04-07 6:55 ` Changheun Lee
2021-04-07 7:40 ` Greg KH
[not found] ` <CGME20210407094610epcas1p472207e8d3ca0e5e697974c993a2a34f7@epcas1p4.samsung.com>
2021-04-07 9:28 ` [RESEND,v5,1/2] " Changheun Lee
2021-04-07 10:27 ` Damien Le Moal
2021-04-09 14:47 ` Bart Van Assche
2021-04-11 22:13 ` Damien Le Moal
2021-04-12 3:23 ` Ming Lei
[not found] ` <CGME20210413045517epcas1p32b058646dd795e59389401ca997c4cac@epcas1p3.samsung.com>
2021-04-13 4:37 ` Changheun Lee
2021-04-13 5:32 ` Christoph Hellwig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210316074401.4594-1-nanich.lee@samsung.com \
--to=nanich.lee@samsung.com \
--cc=Johannes.Thumshirn@wdc.com \
--cc=asml.silence@gmail.com \
--cc=axboe@kernel.dk \
--cc=damien.lemoal@wdc.com \
--cc=gregkh@linuxfoundation.org \
--cc=hch@infradead.org \
--cc=jisoo2146.oh@samsung.com \
--cc=junho89.kim@samsung.com \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=ming.lei@redhat.com \
--cc=mj0123.lee@samsung.com \
--cc=osandov@fb.com \
--cc=patchwork-bot@kernel.org \
--cc=seunghwan.hyun@samsung.com \
--cc=sookwan7.kim@samsung.com \
--cc=tj@kernel.org \
--cc=tom.leiming@gmail.com \
--cc=woosung2.lee@samsung.com \
--cc=yt0928.kim@samsung.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).