linux/block
Yu Kuai 320fb0f91e blk-throttle: fix that io throttle can only work for single bio
Test scripts:
cd /sys/fs/cgroup/blkio/
echo "8:0 1024" > blkio.throttle.write_bps_device
echo $$ > cgroup.procs
dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct &
dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct &

Test result:
10240 bytes (10 kB, 10 KiB) copied, 10.0134 s, 1.0 kB/s
10240 bytes (10 kB, 10 KiB) copied, 10.0135 s, 1.0 kB/s

The problem is that the second bio is finished after 10s instead of 20s.

Root cause:
1) second bio will be flagged:

__blk_throtl_bio
 while (true) {
  ...
  if (sq->nr_queued[rw]) -> some bio is throttled already
   break
 };
 bio_set_flag(bio, BIO_THROTTLED); -> flag the bio

2) flagged bio will be dispatched without waiting:

throtl_dispatch_tg
 tg_may_dispatch
  tg_with_in_bps_limit
   if (bps_limit == U64_MAX || bio_flagged(bio, BIO_THROTTLED))
    *wait = 0; -> wait time is zero
    return true;

commit 9f5ede3c01 ("block: throttle split bio in case of iops limit")
support to count split bios for iops limit, thus it adds flagged bio
checking in tg_with_in_bps_limit() so that split bios will only count
once for bps limit, however, it introduce a new problem that io throttle
won't work if multiple bios are throttled.

In order to fix the problem, handle iops/bps limit in different ways:

1) for iops limit, there is no flag to record if the bio is throttled,
   and iops is always applied.
2) for bps limit, original bio will be flagged with BIO_BPS_THROTTLED,
   and io throttle will ignore bio with the flag.

Noted this patch also remove the code to set flag in __bio_clone(), it's
introduced in commit 111be88398 ("block-throttle: avoid double
charge"), and author thinks split bio can be resubmited and throttled
again, which is wrong because split bio will continue to dispatch from
caller.

Fixes: 9f5ede3c01 ("block: throttle split bio in case of iops limit")
Cc: <stable@vger.kernel.org>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-12 00:19:48 -06:00
..
partitions Folio changes for 6.0 2022-08-03 10:35:43 -07:00
badblocks.c block/badblocks: Remove redundant assignments 2022-04-23 07:15:26 -06:00
bdev.c block: stop using bdevname in bdev_write_inode 2022-07-14 10:27:56 -06:00
bfq-cgroup.c block, bfq: remove unused functions 2022-08-22 10:07:56 -06:00
bfq-iosched.c block, bfq: remove useless parameter for bfq_add/del_bfqq_busy() 2022-08-22 10:07:56 -06:00
bfq-iosched.h block, bfq: remove useless parameter for bfq_add/del_bfqq_busy() 2022-08-22 10:07:56 -06:00
bfq-wf2q.c block, bfq: remove useless parameter for bfq_add/del_bfqq_busy() 2022-08-22 10:07:56 -06:00
bio-integrity.c block: pass struct queue_limits to the bio splitting helpers 2022-08-02 21:08:53 -06:00
bio.c blk-throttle: fix that io throttle can only work for single bio 2022-09-12 00:19:48 -06:00
blk-cgroup-fc-appid.c blk-cgroup: move blkcg_{get,set}_fc_appid out of line 2022-05-02 14:06:20 -06:00
blk-cgroup-rwstat.c blk-cgroup: Fix the recursive blkg rwstat 2021-03-05 11:32:15 -07:00
blk-cgroup-rwstat.h block: Use the new blk_opf_t type 2022-07-14 12:14:30 -06:00
blk-cgroup.c blk-cgroup: Use atomic{,64}_try_cmpxchg 2022-07-12 15:46:03 -06:00
blk-cgroup.h blk-cgroup: Use atomic{,64}_try_cmpxchg 2022-07-12 15:46:03 -06:00
blk-core.c block: remove unneeded return value of bio_check_ro() 2022-09-05 11:45:35 -06:00
blk-crypto-fallback.c block: remove superfluous calls to blkcg_bio_issue_init 2022-05-04 18:29:52 -06:00
blk-crypto-internal.h blk-crypto: show crypto capabilities in sysfs 2022-02-28 06:40:23 -07:00
blk-crypto-profile.c blk-crypto: remove blk_crypto_unregister() 2021-11-29 06:38:51 -07:00
blk-crypto-sysfs.c blk-crypto: show crypto capabilities in sysfs 2022-02-28 06:40:23 -07:00
blk-crypto.c blk-crypto: show crypto capabilities in sysfs 2022-02-28 06:40:23 -07:00
blk-flush.c block: Use the new blk_opf_t type 2022-07-14 12:14:30 -06:00
blk-ia-ranges.c block: simplify disk_set_independent_access_ranges 2022-06-29 08:36:46 -06:00
blk-integrity.c blk-crypto: remove blk_crypto_unregister() 2021-11-29 06:38:51 -07:00
blk-ioc.c block: fix default IO priority handling again 2022-06-27 06:29:12 -06:00
blk-iocost.c block: don't allow the same type rq_qos add more than once 2022-07-20 06:44:14 -06:00
blk-iolatency.c block: don't allow the same type rq_qos add more than once 2022-07-20 06:44:14 -06:00
blk-ioprio.c blk-ioprio: Convert from rqos policy to direct call 2022-06-27 06:29:12 -06:00
blk-ioprio.h blk-ioprio: Convert from rqos policy to direct call 2022-06-27 06:29:12 -06:00
blk-lib.c block: stop using bdevname in __blkdev_issue_discard 2022-07-14 10:27:56 -06:00
blk-map.c block/blk-map: Remove set but unused variable 'added' 2022-09-05 11:44:37 -06:00
blk-merge.c block: pass struct queue_limits to the bio splitting helpers 2022-08-02 21:08:53 -06:00
blk-mq-cpumap.c block: Change the return type of blk_mq_map_queues() into void 2022-08-22 10:07:53 -06:00
blk-mq-debugfs-zoned.c block: move zone related fields to struct gendisk 2022-07-06 06:46:26 -06:00
blk-mq-debugfs.c block: Use the new blk_opf_t type 2022-07-14 12:14:30 -06:00
blk-mq-debugfs.h block: remove per-disk debugfs files in blk_unregister_queue 2022-06-17 07:31:05 -06:00
blk-mq-pci.c block: Change the return type of blk_mq_map_queues() into void 2022-08-22 10:07:53 -06:00
blk-mq-rdma.c block: Change the return type of blk_mq_map_queues() into void 2022-08-22 10:07:53 -06:00
blk-mq-sched.c block: serialize all debugfs operations using q->debugfs_mutex 2022-06-17 07:31:05 -06:00
blk-mq-sched.h block: move blk_mq_sched_assign_ioc to blk-ioc.c 2021-11-29 06:41:29 -07:00
blk-mq-sysfs.c blk-mq: cleanup disk sysfs registration 2022-06-28 11:32:42 -06:00
blk-mq-tag.c sbitmap: fix batched wait_cnt accounting 2022-09-12 00:10:34 -06:00
blk-mq-tag.h blk-mq: blk_mq_tag_busy is no need to return a value 2022-06-27 06:29:12 -06:00
blk-mq-virtio.c block: Change the return type of blk_mq_map_queues() into void 2022-08-22 10:07:53 -06:00
blk-mq.c blk-mq: remove unneeded needs_restart check 2022-09-05 11:45:24 -06:00
blk-mq.h block: Use the new blk_opf_t type 2022-07-14 12:14:30 -06:00
blk-pm.c scsi: block: pm: Always set request queue runtime active in blk_post_runtime_resume() 2021-12-22 23:38:29 -05:00
blk-pm.h block: Remove unused blk_pm_*() function definitions 2021-02-22 06:33:48 -07:00
blk-rq-qos.c block/rq_qos: Use atomic_try_cmpxchg in atomic_inc_below 2022-07-12 14:38:52 -06:00
blk-rq-qos.h block: don't allow the same type rq_qos add more than once 2022-07-20 06:44:14 -06:00
blk-settings.c block: pass a gendisk to blk_queue_clear_zone_settings 2022-07-06 06:46:26 -06:00
blk-stat.c block: make queue stat accounting a reference 2021-12-14 17:23:05 -07:00
blk-stat.h block: make queue stat accounting a reference 2021-12-14 17:23:05 -07:00
blk-sysfs.c block: move ->bio_split to the gendisk 2022-08-02 21:08:49 -06:00
blk-throttle.c blk-throttle: fix that io throttle can only work for single bio 2022-09-12 00:19:48 -06:00
blk-throttle.h blk-throttle: fix that io throttle can only work for single bio 2022-09-12 00:19:48 -06:00
blk-timeout.c block: blk-timeout: delete duplicated word 2020-07-31 16:29:47 -06:00
blk-wbt.c block: don't allow the same type rq_qos add more than once 2022-07-20 06:44:14 -06:00
blk-wbt.h blk-wbt: remove wbt_track stub 2022-03-31 12:58:38 -06:00
blk-zoned.c treewide: Rename enum req_opf into enum req_op 2022-07-14 12:14:30 -06:00
blk.h block: pass struct queue_limits to the bio splitting helpers 2022-08-02 21:08:53 -06:00
bounce.c block: change the blk_queue_bounce calling convention 2022-08-02 17:22:54 -06:00
bsg-lib.c blk-mq: Drop blk_mq_ops.timeout 'reserved' arg 2022-07-06 06:33:53 -06:00
bsg.c scsi: core: bsg: Remove usage of the deprecated ida_simple_xxx() API 2022-06-21 21:22:51 -04:00
disk-events.c block: remove genhd.h 2022-02-02 07:49:59 -07:00
elevator.c for-5.18/block-2022-03-18 2022-03-21 16:48:55 -07:00
elevator.h block: Use the new blk_opf_t type 2022-07-14 12:14:30 -06:00
fops.c new iov_iter flavour - ITER_UBUF 2022-08-08 22:37:15 -04:00
genhd.c block: Do not call blk_put_queue() if gendisk allocation fails 2022-08-12 06:42:06 -06:00
holder.c block: remove WARN_ON() from bd_link_disk_holder 2022-06-23 07:48:05 -06:00
ioctl.c block: replace blkdev_nr_zones with bdev_nr_zones 2022-07-06 06:46:26 -06:00
ioprio.c block: Fix handling of tasks without ioprio in ioprio_get(2) 2022-06-27 06:29:12 -06:00
Kconfig block: remove "select BLK_RQ_IO_DATA_LEN" from BLK_CGROUP_IOCOST dependency 2022-06-29 08:35:57 -06:00
Kconfig.iosched block: only build the icq tracking code when needed 2021-12-16 10:59:02 -07:00
kyber-iosched.c block/kyber: Use the new blk_opf_t type 2022-07-14 12:14:30 -06:00
Makefile blk-cgroup: move blkcg_{get,set}_fc_appid out of line 2022-05-02 14:06:20 -06:00
mq-deadline.c block/mq-deadline: Use the new blk_opf_t type 2022-07-14 12:14:30 -06:00
opal_proto.h block: sed-opal: Add ioctl to return device status 2022-08-22 07:52:51 -06:00
sed-opal.c block: sed-opal: Add ioctl to return device status 2022-08-22 07:52:51 -06:00
t10-pi.c block: add pi for extended integrity 2022-03-07 12:48:35 -07:00