linux/block
Paolo Valente 4420b095cc block, bfq: do not expire a queue that will deserve dispatch plugging
For some bfq_queues, BFQ plugs I/O dispatching when the queue becomes
idle, and keeps the plug until a new request of the queue arrives, or
a timeout fires. BFQ does so either to boost throughput or to preserve
service guarantees for the queue.

More precisely, for such a queue, plugging starts when the queue
happens to have either no request enqueued, or no request in flight,
that is, no request already dispatched but not yet completed.

On the opposite end, BFQ may happen to expire a queue with no request
enqueued, without doing any plugging, if the queue still has some
request in flight. Unfortunately, such a premature expiration causes
the queue to lose its chance to enjoy dispatch plugging a moment
later, i.e., when its in-flight requests finally get completed. This
breaks service guarantees for the queue.

This commit prevents BFQ from expiring an empty queue if the latter
still has in-flight requests.

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:52 -06:00
..
partitions treewide: Use array_size() in vzalloc() 2018-06-12 16:19:22 -07:00
badblocks.c badblocks: fix wrong return value in badblocks_set if badblocks are disabled 2017-11-03 11:29:50 -07:00
bfq-cgroup.c block: use ktime_get_ns() instead of sched_clock() for cfq and bfq 2018-05-09 08:33:06 -06:00
bfq-iosched.c block, bfq: do not expire a queue that will deserve dispatch plugging 2018-07-09 09:07:52 -06:00
bfq-iosched.h block, bfq: add/remove entity weights correctly 2018-07-09 09:07:52 -06:00
bfq-wf2q.c block, bfq: add/remove entity weights correctly 2018-07-09 09:07:52 -06:00
bio-integrity.c block: Convert bio_set to mempool_init() 2018-05-14 13:16:03 -06:00
bio.c for-linus-20180623 2018-06-24 06:33:54 +08:00
blk-cgroup.c blkcg: init root blkcg_gq under lock 2018-04-19 08:51:59 -06:00
blk-core.c block: Fix cloning of requests with a special payload 2018-06-28 09:51:30 -06:00
blk-exec.c blk-mq-sched: remove unused 'can_block' arg from blk_mq_sched_insert_request 2018-01-17 09:49:21 -07:00
blk-flush.c block: fix use-after-free in block flush handling 2018-06-09 06:37:14 -06:00
blk-integrity.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
blk-ioc.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-lib.c block: break discard submissions into the user defined size 2018-05-08 15:10:44 -06:00
blk-map.c Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
blk-merge.c block: don't use blocking queue entered for recursive bio submits 2018-06-02 20:35:00 -06:00
blk-mq-cpumap.c blk-mq: don't keep offline CPUs mapped to hctx 0 2018-04-10 08:38:46 -06:00
blk-mq-debugfs-zoned.c block: Make struct request_queue smaller for CONFIG_BLK_DEV_ZONED=n 2018-07-09 09:07:52 -06:00
blk-mq-debugfs.c block: Make struct request_queue smaller for CONFIG_BLK_DEV_ZONED=n 2018-07-09 09:07:52 -06:00
blk-mq-debugfs.h block: Make struct request_queue smaller for CONFIG_BLK_DEV_ZONED=n 2018-07-09 09:07:52 -06:00
blk-mq-pci.c blk-mq: Allow PCI vector offset for mapping queues 2018-03-27 21:25:36 -06:00
blk-mq-rdma.c block: Add rdma affinity based queue mapping helper 2017-08-08 14:58:03 -04:00
blk-mq-sched.c blk-mq: update nr_requests when switching to 'none' scheduler 2018-06-02 20:35:00 -06:00
blk-mq-sched.h block: move sysfs_lock into elevator_init 2018-06-01 07:38:19 -06:00
blk-mq-sysfs.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
blk-mq-tag.c blk-mq: remove blk_mq_tagset_iter 2018-06-14 17:01:45 +02:00
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 blk-mq: provide a default queue mapping for virtio device 2017-02-27 20:54:05 +02:00
blk-mq.c for-linus-20180629 2018-06-30 10:47:46 -07:00
blk-mq.h blk-mq: Remove generation seqeunce 2018-05-29 08:59:21 -06:00
blk-settings.c block: Introduce blk_queue_flag_{set,clear,test_and_{set,clear}}() 2018-03-08 14:13:48 -07:00
blk-softirq.c block: fix timeout changes for legacy request drivers 2018-06-19 11:27:18 -06:00
blk-stat.c block: consolidate struct request timestamp fields 2018-05-09 08:33:09 -06:00
blk-stat.h block: consolidate struct request timestamp fields 2018-05-09 08:33:09 -06:00
blk-sysfs.c block: convert bounce, q->bio_split to bioset_init()/mempool_init() 2018-05-30 15:33:32 -06:00
blk-tag.c for-linus-20180616 2018-06-17 05:37:55 +09:00
blk-throttle.c blk-throttle: return proper bool type to caller instead of 0/1 2018-05-30 12:48:22 -06:00
blk-timeout.c blk-mq: Fix timeout handling in case the timeout handler returns BLK_EH_DONE 2018-06-23 10:25:45 -06:00
blk-wbt.c block: get rid of struct blk_issue_stat 2018-05-09 08:33:05 -06:00
blk-wbt.h block: get rid of struct blk_issue_stat 2018-05-09 08:33:05 -06:00
blk-zoned.c block: Remove a superfluous cast from blkdev_report_zones() 2018-07-09 09:07:52 -06:00
blk.h block: split the blk-mq case from elevator_init 2018-06-01 07:38:21 -06:00
bounce.c block: fixup bioset_integrity_create() call 2018-05-30 18:51:21 -06:00
bsg-lib.c block: remove parent device reference from struct bsg_class_device 2018-05-29 13:00:25 -06:00
bsg.c bsg: fix race of bsg_open and bsg_unregister 2018-06-15 08:15:37 -06:00
cfq-iosched.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -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
deadline-iosched.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
elevator.c block: split the blk-mq case from elevator_init 2018-06-01 07:38:21 -06:00
genhd.c Merge branch 'hch.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-06-04 10:00:01 -07:00
ioctl.c block: pass inclusive 'lend' parameter to truncate_inode_pages_range 2018-02-23 15:20:19 -07:00
ioprio.c block: add ioprio_check_cap function 2018-05-31 10:50:54 -04:00
Kconfig block: Make struct request_queue smaller for CONFIG_BLK_DEV_ZONED=n 2018-07-09 09:07:52 -06:00
Kconfig.iosched License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kyber-iosched.c block: kyber: make kyber more friendly with merging 2018-05-30 10:47:40 -06:00
Makefile block: Make struct request_queue smaller for CONFIG_BLK_DEV_ZONED=n 2018-07-09 09:07:52 -06:00
mq-deadline.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
noop-iosched.c block: move existing elevator ops to union 2017-01-17 10:03:33 -07:00
opal_proto.h block: sed-opal: Set MBRDone on S3 resume path if TPER is MBREnabled 2017-09-11 09:45:52 -06:00
partition-generic.c block: don't print a message when the device went away 2018-05-29 08:59:21 -06:00
scsi_ioctl.c block: consistently use GFP_NOIO instead of __GFP_NORECLAIM 2018-05-14 08:55:18 -06:00
sed-opal.c block: sed-opal: Fix a couple off by one bugs 2018-06-20 12:04:06 -06:00
t10-pi.c t10-pi: Move opencoded contants to common header 2017-07-03 16:56:25 -06:00