From: Yu Kuai <yukuai3@huawei.com> To: <tj@kernel.org>, <axboe@kernel.dk>, <ming.lei@redhat.com>, <geert@linux-m68k.org> Cc: <cgroups@vger.kernel.org>, <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <yukuai3@huawei.com>, <yi.zhang@huawei.com> Subject: [PATCH -next v3 1/2] blk-throttle: fix that io throttle can only work for single bio Date: Thu, 19 May 2022 16:58:10 +0800 [thread overview] Message-ID: <20220519085811.879097-2-yukuai3@huawei.com> (raw) In-Reply-To: <20220519085811.879097-1-yukuai3@huawei.com> commit 9f5ede3c01f9 ("block: throttle split bio in case of iops limit") introduce a new problem, for example: [root@localhost ~]# echo "8:0 1024" > /sys/fs/cgroup/blkio/blkio.throttle.write_bps_device [root@localhost ~]# echo $$ > /sys/fs/cgroup/blkio/cgroup.procs [root@localhost ~]# dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct & [1] 620 [root@localhost ~]# dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct & [2] 626 [root@localhost ~]# 1+0 records in 1+0 records out 10240 bytes (10 kB, 10 KiB) copied, 10.0038 s, 1.0 kB/s1+0 records in 1+0 records out 10240 bytes (10 kB, 10 KiB) copied, 9.23076 s, 1.1 kB/s -> the second bio is issued after 10s instead of 20s. This is because if some bios are already queued, current bio is queued directly and the flag 'BIO_THROTTLED' is set. And later, when former bios are dispatched, this bio will be dispatched without waiting at all, this is due to tg_with_in_bps_limit() return 0 for this bio. In order to fix the problem, don't skip flaged bio in tg_with_in_bps_limit(), and for the problem that split bio can be double accounted, compensate the over-accounting in __blk_throtl_bio(). Fixes: 9f5ede3c01f9 ("block: throttle split bio in case of iops limit") Signed-off-by: Yu Kuai <yukuai3@huawei.com> --- block/blk-throttle.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 447e1b8722f7..0c37be08ff28 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -811,7 +811,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, unsigned int bio_size = throtl_bio_data_size(bio); /* no need to throttle if this bio's bytes have been accounted */ - if (bps_limit == U64_MAX || bio_flagged(bio, BIO_THROTTLED)) { + if (bps_limit == U64_MAX) { if (wait) *wait = 0; return true; @@ -921,11 +921,8 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) unsigned int bio_size = throtl_bio_data_size(bio); /* Charge the bio to the group */ - if (!bio_flagged(bio, BIO_THROTTLED)) { - tg->bytes_disp[rw] += bio_size; - tg->last_bytes_disp[rw] += bio_size; - } - + tg->bytes_disp[rw] += bio_size; + tg->last_bytes_disp[rw] += bio_size; tg->io_disp[rw]++; tg->last_io_disp[rw]++; @@ -2121,6 +2118,21 @@ bool __blk_throtl_bio(struct bio *bio) tg->last_low_overflow_time[rw] = jiffies; throtl_downgrade_check(tg); throtl_upgrade_check(tg); + + /* + * re-entered bio has accounted bytes already, so try to + * compensate previous over-accounting. However, if new + * slice is started, just forget it. + */ + if (bio_flagged(bio, BIO_THROTTLED)) { + unsigned int bio_size = throtl_bio_data_size(bio); + + if (tg->bytes_disp[rw] >= bio_size) + tg->bytes_disp[rw] -= bio_size; + if (tg->last_bytes_disp[rw] >= bio_size) + tg->last_bytes_disp[rw] -= bio_size; + } + /* throtl is FIFO - if bios are already queued, should queue */ if (sq->nr_queued[rw]) break; -- 2.31.1
WARNING: multiple messages have this Message-ID (diff)
From: Yu Kuai <yukuai3@huawei.com> To: tj@kernel.org, axboe@kernel.dk, ming.lei@redhat.com, geert@linux-m68k.org Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yi.zhang@huawei.com Subject: [PATCH -next v3 1/2] blk-throttle: fix that io throttle can only work for single bio Date: Thu, 19 May 2022 16:58:10 +0800 [thread overview] Message-ID: <20220519085811.879097-2-yukuai3@huawei.com> (raw) In-Reply-To: <20220519085811.879097-1-yukuai3@huawei.com> commit 9f5ede3c01f9 ("block: throttle split bio in case of iops limit") introduce a new problem, for example: [root@localhost ~]# echo "8:0 1024" > /sys/fs/cgroup/blkio/blkio.throttle.write_bps_device [root@localhost ~]# echo $$ > /sys/fs/cgroup/blkio/cgroup.procs [root@localhost ~]# dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct & [1] 620 [root@localhost ~]# dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct & [2] 626 [root@localhost ~]# 1+0 records in 1+0 records out 10240 bytes (10 kB, 10 KiB) copied, 10.0038 s, 1.0 kB/s1+0 records in 1+0 records out 10240 bytes (10 kB, 10 KiB) copied, 9.23076 s, 1.1 kB/s -> the second bio is issued after 10s instead of 20s. This is because if some bios are already queued, current bio is queued directly and the flag 'BIO_THROTTLED' is set. And later, when former bios are dispatched, this bio will be dispatched without waiting at all, this is due to tg_with_in_bps_limit() return 0 for this bio. In order to fix the problem, don't skip flaged bio in tg_with_in_bps_limit(), and for the problem that split bio can be double accounted, compensate the over-accounting in __blk_throtl_bio(). Fixes: 9f5ede3c01f9 ("block: throttle split bio in case of iops limit") Signed-off-by: Yu Kuai <yukuai3@huawei.com> --- block/blk-throttle.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 447e1b8722f7..0c37be08ff28 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -811,7 +811,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, unsigned int bio_size = throtl_bio_data_size(bio); /* no need to throttle if this bio's bytes have been accounted */ - if (bps_limit == U64_MAX || bio_flagged(bio, BIO_THROTTLED)) { + if (bps_limit == U64_MAX) { if (wait) *wait = 0; return true; @@ -921,11 +921,8 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) unsigned int bio_size = throtl_bio_data_size(bio); /* Charge the bio to the group */ - if (!bio_flagged(bio, BIO_THROTTLED)) { - tg->bytes_disp[rw] += bio_size; - tg->last_bytes_disp[rw] += bio_size; - } - + tg->bytes_disp[rw] += bio_size; + tg->last_bytes_disp[rw] += bio_size; tg->io_disp[rw]++; tg->last_io_disp[rw]++; @@ -2121,6 +2118,21 @@ bool __blk_throtl_bio(struct bio *bio) tg->last_low_overflow_time[rw] = jiffies; throtl_downgrade_check(tg); throtl_upgrade_check(tg); + + /* + * re-entered bio has accounted bytes already, so try to + * compensate previous over-accounting. However, if new + * slice is started, just forget it. + */ + if (bio_flagged(bio, BIO_THROTTLED)) { + unsigned int bio_size = throtl_bio_data_size(bio); + + if (tg->bytes_disp[rw] >= bio_size) + tg->bytes_disp[rw] -= bio_size; + if (tg->last_bytes_disp[rw] >= bio_size) + tg->last_bytes_disp[rw] -= bio_size; + } + /* throtl is FIFO - if bios are already queued, should queue */ if (sq->nr_queued[rw]) break; -- 2.31.1
next prev parent reply other threads:[~2022-05-19 8:44 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-19 8:58 [PATCH -next v3 0/2] bugfix for blk-throttle Yu Kuai 2022-05-19 8:58 ` Yu Kuai 2022-05-19 8:58 ` Yu Kuai [this message] 2022-05-19 8:58 ` [PATCH -next v3 1/2] blk-throttle: fix that io throttle can only work for single bio Yu Kuai 2022-05-19 10:42 ` Ming Lei 2022-05-19 8:58 ` [PATCH -next v3 2/2] blk-throttle: fix io hung due to configuration updates Yu Kuai 2022-05-19 8:58 ` Yu Kuai 2022-05-19 9:58 ` Michal Koutný 2022-05-19 12:14 ` yukuai (C) 2022-05-19 12:14 ` yukuai (C) 2022-05-19 16:10 ` Michal Koutný 2022-05-19 16:10 ` Michal Koutný 2022-05-20 1:22 ` yukuai (C) 2022-05-20 1:22 ` yukuai (C) 2022-05-20 1:36 ` yukuai (C) 2022-05-20 1:36 ` yukuai (C) 2022-05-20 16:03 ` Michal Koutný 2022-05-20 16:20 ` Tejun Heo 2022-05-21 3:51 ` yukuai (C) 2022-05-21 3:51 ` yukuai (C) 2022-05-21 5:00 ` Tejun Heo 2022-05-21 5:00 ` Tejun Heo 2022-05-21 3:01 ` yukuai (C) 2022-05-21 3:01 ` yukuai (C)
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