kernel_optimize_test/block
Tejun Heo 36a524814f blk-iocost: Account force-charged overage in absolute vtime
Currently, when a bio needs to be force-charged and there isn't enough
budget, vtime is simply pushed into the future.  This means that the
cost of the whole bio is scaled using the current hweight and then
charged immediately.  Until the global vtime advances beyond this
future vtime, the cgroup won't be allowed to issue normal IOs.

This is incorrect and can lead to, for example, exploding vrate or
extended stalls if vrate range is constrained.  Consider the following
scenario.

1. A cgroup with a very low hweight runs out of budget.

2. A storm of swap-out happens on it.  All of them are scaled
   according to the current low hweight and charged to vtime pushing
   it to a far future.

3. All other cgroups go idle and now the above cgroup has access to
   the whole device.  However, because vtime is already wound using
   the past low hweight, what its current hweight is doesn't matter
   until global vtime catches up to the local vtime.

4. As a result, either vrate gets ramped up extremely or the IOs stall
   while the underlying device is idle.

This is because the hweight the overage is calculated at is different
from the hweight that it's being paid at.

Fix it by remembering the overage in absoulte vtime and continuously
paying with the actual budget according to the current hweight at each
period.

Note that non-forced bios which wait already remembers the cost in
absolute vtime.  This brings forced-bio accounting in line.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-10 12:31:39 -06:00
..
partitions docs: admin-guide: add a series of orphaned documents 2019-07-15 11:03:02 -03:00
badblocks.c block: switch all files cleared marked as GPLv2 to SPDX tags 2019-04-30 16:11:57 -06:00
bfq-cgroup.c bfq: Add per-device weight 2019-09-06 14:33:52 -06:00
bfq-iosched.c for-linus-20190726 2019-07-26 10:32:12 -07:00
bfq-iosched.h bfq: Add per-device weight 2019-09-06 14:33:52 -06:00
bfq-wf2q.c bfq: Fix the missing barrier in __bfq_entity_update_weight_prio 2019-09-06 14:33:48 -06:00
bio-integrity.c block/bio-integrity: fix a memory leak bug 2019-07-11 20:01:21 -06:00
bio.c block: move same page handling from __bio_add_pc_page to the callers 2019-08-22 07:14:39 -06:00
blk-cgroup.c blkcg: separate blkcg_conf_get_disk() out of blkg_conf_prep() 2019-08-28 21:17:04 -06:00
blk-core.c block/rq_qos: add rq_qos_merge() 2019-08-28 21:17:05 -06:00
blk-exec.c block: add SPDX tags to block layer files missing licensing information 2019-04-30 16:12:03 -06:00
blk-flush.c block: switch all files cleared marked as GPLv2 to SPDX tags 2019-04-30 16:11:57 -06:00
blk-integrity.c docs: block: convert to ReST 2019-07-15 09:20:27 -03:00
blk-ioc.c block: remove the queue_lock indirection 2018-11-15 12:17:28 -07:00
blk-iocost.c blk-iocost: Account force-charged overage in absolute vtime 2019-09-10 12:31:39 -06:00
blk-iolatency.c blkcg: s/RQ_QOS_CGROUP/RQ_QOS_LATENCY/ 2019-08-28 21:17:08 -06:00
blk-lib.c block: fix 32 bit overflow in __blkdev_issue_discard() 2018-11-14 08:17:18 -07:00
blk-map.c block: remove the bi_phys_segments field in struct bio 2019-06-20 10:29:22 -06:00
blk-merge.c block: Improve physical block alignment of split bios 2019-08-04 21:41:29 -06:00
blk-mq-cpumap.c blk-mq: balance mapping between present CPUs and queues 2019-08-04 21:43:12 -06:00
blk-mq-debugfs-zoned.c block: Cleanup license notice 2019-01-17 21:21:40 -07:00
blk-mq-debugfs.c for-5.3/block-20190708 2019-07-09 10:45:06 -07:00
blk-mq-debugfs.h blk-mq: no need to check return value of debugfs_create functions 2019-06-13 03:00:30 -06:00
blk-mq-pci.c block: Fix blk_mq_*_map_queues() kernel-doc headers 2019-05-31 15:12:34 -06:00
blk-mq-rdma.c block: Fix blk_mq_*_map_queues() kernel-doc headers 2019-05-31 15:12:34 -06:00
blk-mq-sched.c blk-mq: remove blk_mq_put_ctx() 2019-07-02 21:03:27 -06:00
blk-mq-sched.h block: blk-mq: Remove blk_mq_sched_started_request and started_request 2019-07-23 07:25:09 -06:00
blk-mq-sysfs.c block: split .sysfs_lock into two locks 2019-08-27 10:40:20 -06:00
blk-mq-tag.c blk-mq: introduce blk_mq_tagset_wait_completed_request() 2019-08-04 21:41:29 -06:00
blk-mq-tag.h Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
blk-mq-virtio.c block: Fix blk_mq_*_map_queues() kernel-doc headers 2019-05-31 15:12:34 -06:00
blk-mq.c block: Delay default elevator initialization 2019-09-05 19:52:34 -06:00
blk-mq.h block: Disable write plugging for zoned block devices 2019-07-10 14:18:01 -06:00
blk-pm.c block: remove the queue_lock indirection 2018-11-15 12:17:28 -07:00
blk-pm.h block: remove the queue_lock indirection 2018-11-15 12:17:28 -07:00
blk-rq-qos.c block/rq_qos: implement rq_qos_ops->queue_depth_changed() 2019-08-28 21:17:07 -06:00
blk-rq-qos.h blkcg: implement blk-iocost 2019-08-28 21:17:12 -06:00
blk-settings.c block: Introduce elevator features 2019-09-05 19:52:33 -06:00
blk-softirq.c block: remove a few unused exports 2018-11-15 12:13:25 -07:00
blk-stat.c block: add SPDX tags to block layer files missing licensing information 2019-04-30 16:12:03 -06:00
blk-stat.h block: deactivate blk_stat timer in wbt_disable_default() 2018-12-12 06:47:51 -07:00
blk-sysfs.c block: split .sysfs_lock into two locks 2019-08-27 10:40:20 -06:00
blk-throttle.c blkcg: pass @q and @blkcg into blkcg_pol_alloc_pd_fn() 2019-08-28 21:17:01 -06:00
blk-timeout.c block: add SPDX tags to block layer files missing licensing information 2019-04-30 16:12:03 -06:00
blk-wbt.c block/rq_qos: implement rq_qos_ops->queue_depth_changed() 2019-08-28 21:17:07 -06:00
blk-wbt.h block/rq_qos: implement rq_qos_ops->queue_depth_changed() 2019-08-28 21:17:07 -06:00
blk-zoned.c blk-zoned: implement REQ_OP_ZONE_RESET_ALL 2019-08-04 21:41:29 -06:00
blk.h block: Change elevator_init_mq() to always succeed 2019-09-05 19:52:33 -06:00
bounce.c block: remove the i argument to bio_for_each_segment_all 2019-04-30 09:26:13 -06:00
bsg-lib.c block: Fix bsg_setup_queue() kernel-doc header 2019-05-31 15:12:34 -06:00
bsg.c block: switch all files cleared marked as GPLv2 to SPDX tags 2019-04-30 16:11:57 -06:00
cmdline-parser.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compat_ioctl.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
elevator.c block: fix elevator_get_by_features() 2019-09-06 07:02:31 -06:00
genhd.c block: Delay default elevator initialization 2019-09-05 19:52:34 -06:00
ioctl.c block: add SPDX tags to block layer files missing licensing information 2019-04-30 16:12:03 -06:00
ioprio.c docs: block: convert to ReST 2019-07-15 09:20:27 -03:00
Kconfig blkcg: implement blk-iocost 2019-08-28 21:17:12 -06:00
Kconfig.iosched docs: block: convert to ReST 2019-07-15 09:20:27 -03:00
kyber-iosched.c blk-mq: remove blk_mq_put_ctx() 2019-07-02 21:03:27 -06:00
Makefile blkcg: implement blk-iocost 2019-08-28 21:17:12 -06:00
mq-deadline.c block: Introduce elevator features 2019-09-05 19:52:33 -06:00
opal_proto.h block: sed-opal: Removed duplicate OPAL_METHOD_LENGTH definition 2019-08-20 09:34:49 -06:00
partition-generic.c block: fix use-after-free on gendisk 2019-04-22 09:48:12 -06:00
scsi_ioctl.c block: switch all files cleared marked as GPLv2 to SPDX tags 2019-04-30 16:11:57 -06:00
sed-opal.c block: sed-opal: Remove always false conditional statement 2019-08-20 09:33:21 -06:00
t10-pi.c block: switch all files cleared marked as GPLv2 to SPDX tags 2019-04-30 16:11:57 -06:00