Hou Tao 3f7cb4f413 bfq: dispatch request to prevent queue stalling after the request completion ... There are mq devices (eg., virtio-blk, nbd and loopback) which don't invoke blk_mq_run_hw_queues() after the completion of a request. If bfq is enabled on these devices and the slice_idle attribute or strict_guarantees attribute is set as zero, it is possible that after a request completion the remaining requests of busy bfq queue will stalled in the bfq schedule until a new request arrives. To fix the scheduler latency problem, we need to check whether or not all issued requests have completed and dispatch more requests to driver if there is no request in driver. The problem can be reproduced by running the following script on a virtio-blk device with nr_hw_queues as 1: #!/bin/sh dev=vdb # mount point for dev mp=/tmp/mnt cd $mp job=strict.job cat <<EOF > $job [global] direct=1 bs=4k size=256M rw=write ioengine=libaio iodepth=128 runtime=5 time_based [1] filename=1.data [2] new_group filename=2.data EOF echo bfq > /sys/block/$dev/queue/scheduler echo 1 > /sys/block/$dev/queue/iosched/strict_guarantees fio $job Signed-off-by: Hou Tao <houtao1@huawei.com> Reviewed-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>		2017-07-12 08:32:04 -06:00
..
partitions	partitions/ldm: switch to use uuid_t	2017-06-05 16:59:14 +02:00
badblocks.c	block: Add fallthrough markers to switch statements	2017-06-21 11:46:07 -06:00
bfq-cgroup.c	block, bfq: access and cache blkg data only when safe	2017-06-08 09:51:10 -06:00
bfq-iosched.c	bfq: dispatch request to prevent queue stalling after the request completion	2017-07-12 08:32:04 -06:00
bfq-iosched.h	bfq: fix typos in comments about B-WF2Q+ algorithm	2017-07-12 08:32:02 -06:00
bfq-wf2q.c	bfq: fix typos in comments about B-WF2Q+ algorithm	2017-07-12 08:32:02 -06:00
bio-integrity.c	bio-integrity: fix boolreturn.cocci warnings	2017-07-04 16:11:53 -06:00
bio.c	block: call bio_uninit in bio_endio	2017-07-10 12:43:33 -06:00
blk-cgroup.c	block: Avoid that blk_exit_rl() triggers a use-after-free	2017-06-01 13:07:55 -06:00
blk-core.c	bio-integrity: fold bio_integrity_enabled to bio_integrity_prep	2017-07-03 16:56:24 -06:00
blk-exec.c	block: introduce new block status code type	2017-06-09 09:27:32 -06:00
blk-flush.c	block: Check locking assumptions at runtime	2017-06-20 19:27:14 -06:00
blk-integrity.c	block: switch bios to blk_status_t	2017-06-09 09:27:32 -06:00
blk-ioc.c
blk-lib.c	block: Fix __blkdev_issue_zeroout loop	2017-07-06 09:43:20 -06:00
blk-map.c	blk-map: call blk_queue_bounce from blk_rq_append_bio	2017-06-27 12:13:21 -06:00
blk-merge.c	block: add support for write hints in a bio	2017-06-27 12:05:27 -06:00
blk-mq-cpumap.c	Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-07-03 16:50:31 -07:00
blk-mq-debugfs.c	blk-mq: expose write hints through debugfs	2017-06-27 12:05:31 -06:00
blk-mq-debugfs.h	mq-deadline: add debugfs attributes	2017-05-04 08:25:17 -06:00
blk-mq-pci.c
blk-mq-sched.c	blk-mq-sched: fix performance regression of mq-deadline	2017-07-03 16:54:09 -06:00
blk-mq-sched.h	Merge commit '8e8320c9315c' into for-4.13/block	2017-06-22 21:55:24 -06:00
blk-mq-sysfs.c	blk-mq: untangle debugfs and sysfs	2017-05-04 08:24:13 -06:00
blk-mq-tag.c	blk-mq: add shallow depth option for blk_mq_get_tag()	2017-04-14 14:06:54 -06:00
blk-mq-tag.h
blk-mq-virtio.c
blk-mq.c	Merge branch 'for-linus' of git://git.kernel.dk/linux-block	2017-07-11 15:36:52 -07:00
blk-mq.h	Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-07-03 16:50:31 -07:00
blk-settings.c	block: don't bother with bounce limits for make_request drivers	2017-06-27 12:13:45 -06:00
blk-softirq.c
blk-stat.c	blk-stat: don't use this_cpu_ptr() in a preemptable section	2017-05-10 07:40:18 -06:00
blk-stat.h	blk-stat: kill blk_stat_rq_ddir()	2017-04-21 07:56:23 -06:00
blk-sysfs.c	block: Fix a blk_exit_rl() regression	2017-06-14 13:27:50 -06:00
blk-tag.c	block: Check locking assumptions at runtime	2017-06-20 19:27:14 -06:00
blk-throttle.c	blk-throttle: set default latency baseline for harddisk	2017-06-07 09:09:32 -06:00
blk-timeout.c	block: Check locking assumptions at runtime	2017-06-20 19:27:14 -06:00
blk-wbt.c	sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming	2017-06-20 12:19:14 +02:00
blk-wbt.h	block: Make writeback throttling defaults consistent for SQ devices	2017-04-19 08:49:03 -06:00
blk-zoned.c
blk.h	bio-integrity: stop abusing bi_end_io	2017-07-03 17:00:59 -06:00
bounce.c	block: remove the queue_bounce_pfn helper	2017-06-27 12:13:45 -06:00
bsg-lib.c	block: introduce new block status code type	2017-06-09 09:27:32 -06:00
bsg.c	block: Make most scsi_req_init() calls implicit	2017-06-20 19:27:14 -06:00
cfq-iosched.c	Linux 4.12-rc5	2017-06-12 08:30:13 -06:00
cmdline-parser.c
compat_ioctl.c	compat_hdio_ioctl: get rid of set_fs()	2017-06-29 18:17:52 -04:00
deadline-iosched.c
elevator.c	block: Add fallthrough markers to switch statements	2017-06-21 11:46:07 -06:00
genhd.c	block: Constify disk_type	2017-06-20 19:27:14 -06:00
ioctl.c	block: remove the discard_zeroes_data flag	2017-04-08 11:25:38 -06:00
ioprio.c	block: Add fallthrough markers to switch statements	2017-06-21 11:46:07 -06:00
Kconfig	Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm	2017-05-12 15:43:10 -07:00
Kconfig.iosched	block, bfq: add full hierarchical scheduling and cgroups support	2017-04-19 08:30:26 -06:00
kyber-iosched.c	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-07-03 13:08:04 -07:00
Makefile	block, bfq: split bfq-iosched.c into multiple source files	2017-04-19 08:48:24 -06:00
mq-deadline.c	mq-deadline: add debugfs attributes	2017-05-04 08:25:17 -06:00
noop-iosched.c
opal_proto.h
partition-generic.c	block: fix an error code in add_partition()	2017-05-23 08:41:59 -06:00
scsi_ioctl.c	block: Change argument type of scsi_req_init()	2017-06-20 19:27:14 -06:00
sed-opal.c
t10-pi.c	t10-pi: Move opencoded contants to common header	2017-07-03 16:56:25 -06:00