linux/block
Paolo Valente 3e2bdd6dff block, bfq: check and switch back to interactive wr also on queue split
As already explained in the message of commit "block, bfq: fix
wrong init of saved start time for weight raising", if a soft
real-time weight-raising period happens to be nested in a larger
interactive weight-raising period, then BFQ restores the interactive
weight raising at the end of the soft real-time weight raising. In
particular, BFQ checks whether the latter has ended only on request
dispatches.

Unfortunately, the above scheme fails to restore interactive weight
raising in the following corner case: if a bfq_queue, say Q,
1) Is merged with another bfq_queue while it is in a nested soft
real-time weight-raising period. The weight-raising state of Q is
then saved, and not considered any longer until a split occurs.
2) Is split from the other bfq_queue(s) at a time instant when its
soft real-time weight raising is already finished.
On the split, while resuming the previous, soft real-time
weight-raised state of the bfq_queue Q, BFQ checks whether the
current soft real-time weight-raising period is actually over. If so,
BFQ switches weight raising off for Q, *without* checking whether the
soft real-time period was actually nested in a non-yet-finished
interactive weight-raising period.

This commit addresses this issue by adding the above missing check in
bfq_queue splits, and restoring interactive weight raising if needed.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Angelo Ruocco <angeloruocco90@gmail.com>
Tested-by: Mirko Montanari <mirkomontanari91@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-03 08:40:56 -06:00
..
partitions
badblocks.c
bfq-cgroup.c bfq: Declare local functions static 2017-09-01 13:56:37 -06:00
bfq-iosched.c block, bfq: check and switch back to interactive wr also on queue split 2017-10-03 08:40:56 -06:00
bfq-iosched.h Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
bfq-wf2q.c block, bfq: guarantee update_next_in_service always returns an eligible entity 2017-08-31 08:20:31 -06:00
bio-integrity.c Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
bio.c blkcg: delete unused APIs 2017-09-26 07:41:22 -06:00
blk-cgroup.c
blk-core.c blktrace: Fix potential deadlock between delete & sysfs ops 2017-09-25 08:56:05 -06:00
blk-exec.c
blk-flush.c
blk-integrity.c
blk-ioc.c
blk-lib.c block: fix integer overflow in __blkdev_sectors_to_bio_pages() 2017-09-11 09:46:49 -06:00
blk-map.c
blk-merge.c
blk-mq-cpumap.c
blk-mq-debugfs.c Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
blk-mq-debugfs.h
blk-mq-pci.c
blk-mq-rdma.c
blk-mq-sched.c
blk-mq-sched.h
blk-mq-sysfs.c
blk-mq-tag.c
blk-mq-tag.h blk-mq-tag: kill unused tag enums 2017-10-01 01:26:21 -06:00
blk-mq-virtio.c
blk-mq.c blk-mq: wire up completion notifier for laptop mode 2017-10-03 08:38:17 -06:00
blk-mq.h block: directly insert blk-mq request from blk_insert_cloned_request() 2017-09-11 16:43:57 -06:00
blk-settings.c
blk-softirq.c
blk-stat.c
blk-stat.h
blk-sysfs.c
blk-tag.c
blk-throttle.c Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
blk-timeout.c
blk-wbt.c
blk-wbt.h
blk-zoned.c
blk.h
bounce.c
bsg-lib.c bsg-lib: don't free job in bsg_prepare_job 2017-09-25 08:56:05 -06:00
bsg.c bsg: remove #if 0'ed code 2017-08-29 10:50:30 -06:00
cfq-iosched.c block/cfq: cache rightmost rb_node 2017-09-08 18:26:49 -07:00
cmdline-parser.c
compat_ioctl.c compat_hdio_ioctl: Fix a declaration 2017-08-31 17:32:41 -04:00
deadline-iosched.c
elevator.c
genhd.c Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
ioctl.c
ioprio.c
Kconfig
Kconfig.iosched
kyber-iosched.c
Makefile
mq-deadline.c mq-deadline: Enable auto-loading when built as module 2017-08-29 10:47:23 -06:00
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 block: fix a crash caused by wrong API 2017-09-25 08:56:05 -06:00
scsi_ioctl.c
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