AcoSail/kernel_optimize_test
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86ff7c2a80
kernel_optimize_test/block
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Ming Lei 86ff7c2a80 blk-mq: introduce BLK_STS_DEV_RESOURCE 
This status is returned from driver to block layer if device related
resource is unavailable, but driver can guarantee that IO dispatch
will be triggered in future when the resource is available.

Convert some drivers to return BLK_STS_DEV_RESOURCE.  Also, if driver
returns BLK_STS_RESOURCE and SCHED_RESTART is set, rerun queue after
a delay (BLK_MQ_DELAY_QUEUE) to avoid IO stalls.  BLK_MQ_DELAY_QUEUE is
3 ms because both scsi-mq and nvmefc are using that magic value.

If a driver can make sure there is in-flight IO, it is safe to return
BLK_STS_DEV_RESOURCE because:

1) If all in-flight IOs complete before examining SCHED_RESTART in
blk_mq_dispatch_rq_list(), SCHED_RESTART must be cleared, so queue
is run immediately in this case by blk_mq_dispatch_rq_list();

2) if there is any in-flight IO after/when examining SCHED_RESTART
in blk_mq_dispatch_rq_list():
- if SCHED_RESTART isn't set, queue is run immediately as handled in 1)
- otherwise, this request will be dispatched after any in-flight IO is
  completed via blk_mq_sched_restart()

3) if SCHED_RESTART is set concurently in context because of
BLK_STS_RESOURCE, blk_mq_delay_run_hw_queue() will cover the above two
cases and make sure IO hang can be avoided.

One invariant is that queue will be rerun if SCHED_RESTART is set.

Suggested-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-30 20:18:28 -07:00
..
partitions partitions/msdos: Unable to mount UFS 44bsd partitions 2018-01-10 09:12:16 -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, bfq: put async queues for root bfq groups too 2018-01-09 08:45:25 -07:00
bfq-iosched.c block, bfq: limit sectors served with interactive weight raising 2018-01-18 08:21:37 -07:00
bfq-iosched.h block, bfq: limit sectors served with interactive weight raising 2018-01-18 08:21:37 -07:00
bfq-wf2q.c block, bfq: limit sectors served with interactive weight raising 2018-01-18 08:21:37 -07:00
bio-integrity.c block: Fix __bio_integrity_endio() documentation 2018-01-17 09:59:33 -07:00
bio.c Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
blk-cgroup.c blkcg: add sanity check for blkcg policy operations 2017-11-04 12:31:15 -06:00
blk-core.c blk-mq: introduce BLK_STS_DEV_RESOURCE 2018-01-30 20:18:28 -07:00
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 blk-mq: don't allocate driver tag upfront for flush rq 2017-11-04 12:40:13 -06:00
blk-integrity.c
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: add bdev_read_only() checks to common helpers 2018-01-18 12:57:19 -07:00
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 Revert "block: blk-merge: try to make front segments in full size" 2018-01-09 20:23:19 -07:00
blk-mq-cpumap.c blk-mq: map queues to all present CPUs 2017-07-24 10:01:31 -06:00
blk-mq-debugfs.c blk-mq-debugfs: don't allow write on attributes with seq_operations set 2018-01-24 09:46:09 -07:00
blk-mq-debugfs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-mq-pci.c blk-mq-pci: add a fallback when pci_irq_get_affinity returns NULL 2017-08-18 08:08:14 -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-sched: remove unused 'can_block' arg from blk_mq_sched_insert_request 2018-01-17 09:49:21 -07:00
blk-mq-sched.h blk-mq-sched: remove unused 'can_block' arg from blk_mq_sched_insert_request 2018-01-17 09:49:21 -07:00
blk-mq-sysfs.c block: properly protect the 'queue' kobj in blk_unregister_queue 2018-01-15 08:41:38 -07:00
blk-mq-tag.c blk-mq: improve heavily contended tag case 2017-12-22 11:09:37 -07:00
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.c blk-mq: introduce BLK_STS_DEV_RESOURCE 2018-01-30 20:18:28 -07:00
blk-mq.h blk-mq: Rename blk_mq_request_direct_issue() into blk_mq_request_issue_directly() 2018-01-19 12:51:59 -07:00
blk-settings.c block: remove __bio_kmap_atomic 2017-11-10 19:53:25 -07:00
blk-softirq.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-stat.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
blk-stat.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-sysfs.c block: Protect less code with sysfs_lock in blk_{un,}register_queue() 2018-01-18 12:54:44 -07:00
blk-tag.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-throttle.c Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
blk-timeout.c block: add accessors for setting/querying request deadline 2018-01-10 11:47:47 -07:00
blk-wbt.c blk-wbt: fix comments typo 2017-11-23 22:00:20 -07:00
blk-wbt.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-zoned.c block: introduce zoned block devices zone write locking 2018-01-05 09:22:17 -07:00
blk.h Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
bounce.c Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
bsg-lib.c block: Fix kernel-doc warnings reported when building with W=1 2018-01-09 11:15:17 -07:00
bsg.c bsg: use pr_debug instead of hand crafted macros 2018-01-24 09:50:06 -07:00
cfq-iosched.c block/cfq: cache rightmost rb_node 2017-09-08 18:26:49 -07:00
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 deadline-iosched: Introduce zone locking support 2018-01-05 09:22:17 -07:00
elevator.c block: Document scheduler modification locking requirements 2018-01-18 12:54:42 -07:00
genhd.c block: allow gendisk's request_queue registration to be deferred 2018-01-15 08:41:38 -07:00
ioctl.c block: move CAP_SYS_ADMIN check in blkdev_roset() 2017-10-25 12:25:00 -06:00
ioprio.c
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
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 kyber: fix another domain token wait queue hang 2017-12-06 12:33:07 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mq-deadline.c mq-deadline: make it clear that __dd_dispatch_request() works on all hw queues 2018-01-06 09:23:11 -07:00
noop-iosched.c
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 License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
scsi_ioctl.c block: silently forbid sending any ioctl to a partition 2018-01-10 12:30:37 -07:00
sed-opal.c block: sed-opal: Set MBRDone on S3 resume path if TPER is MBREnabled 2017-09-11 09:45:52 -06:00
t10-pi.c t10-pi: Move opencoded contants to common header 2017-07-03 16:56:25 -06:00