Federico Motta 98fa7a3e00 block, bfq: fix asymmetric scenarios detection ... Since commit 2d29c9f89f ("block, bfq: improve asymmetric scenarios detection"), a scenario is defined asymmetric when one of the following conditions holds: - active bfq_queues have different weights - one or more group of entities (bfq_queue or other groups of entities) are active bfq grants fairness and low latency also in such asymmetric scenarios, by plugging the dispatching of I/O if the bfq_queue in service happens to be temporarily idle. This plugging may lower throughput, so it is important to do it only when strictly needed. By mistake, in commit '2d29c9f89fcd' ("block, bfq: improve asymmetric scenarios detection") the num_active_groups counter was firstly incremented and subsequently decremented at any entity (group or bfq_queue) weight change. This is useless, because only transitions from active to inactive and vice versa matter for that counter. Unfortunately this is also incorrect in the following case: the entity at issue is a bfq_queue and it is under weight raising. In fact in this case there is a spurious increment of the num_active_groups counter. This spurious increment may cause scenarios to be wrongly detected as asymmetric, thus causing useless plugging and loss of throughput. This commit fixes this issue by simply removing the above useless and wrong increments and decrements. Fixes: 2d29c9f89f ("block, bfq: improve asymmetric scenarios detection") Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Federico Motta <federico@willer.it> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>		2018-10-25 11:17:40 -06:00
..
partitions	partitions/aix: append null character to print data from disk	2018-07-27 09:17:41 -06:00
Kconfig	block: remove redundant 'default n' from Kconfig-s	2018-10-10 14:11:07 -06:00
Kconfig.iosched	block: remove redundant 'default n' from Kconfig-s	2018-10-10 14:11:07 -06:00
Makefile	block: Move power management code into a new source file	2018-09-26 15:11:28 -06:00
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	blkcg: fix ref count issue with bio_blkcg using task_css	2018-09-21 20:29:02 -06:00
bfq-iosched.c	block, bfq: improve asymmetric scenarios detection	2018-10-13 15:40:00 -06:00
bfq-iosched.h	block, bfq: improve asymmetric scenarios detection	2018-10-13 15:40:00 -06:00
bfq-wf2q.c	block, bfq: fix asymmetric scenarios detection	2018-10-25 11:17:40 -06:00
bio-integrity.c	block: remove bio_rewind_iter()	2018-09-06 15:12:24 -06:00
bio.c	blkcg: reassociate bios when make_request() is called recursively	2018-10-20 15:39:55 -06:00
blk-cgroup.c	This is the 4.19-rc6 release	2018-10-01 08:58:57 -06:00
blk-core.c	block: add a report_zones method	2018-10-25 11:17:40 -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	blk-mq: change gfp flags to GFP_NOIO in blk_mq_realloc_hw_ctxs	2018-10-13 15:42:01 -06:00
blk-integrity.c	block: merge BIOVEC_SEG_BOUNDARY into biovec_phys_mergeable	2018-09-24 12:33:57 -06:00
blk-ioc.c	block, mm: remove unnecessary __GFP_HIGH flag	2018-07-09 09:07:54 -06:00
blk-iolatency.c	blk-iolatency: keep track of previous windows stats	2018-09-28 11:47:32 -06:00
blk-lib.c	block: Improve zone reset execution	2018-10-25 11:17:40 -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: merge BIOVEC_SEG_BOUNDARY into biovec_phys_mergeable	2018-09-24 12:33:57 -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: add a report_zones method	2018-10-25 11:17:40 -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: code clean-up by adding an API to clear set->mq_map	2018-07-09 09:07:53 -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: init hctx sched after update ctx and hctx mapping	2018-08-21 09:02:55 -06:00
blk-mq-sched.h	block: move call of scheduler's ->completed_request() hook	2018-09-27 17:34:52 -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	This is the 4.19-rc6 release	2018-10-01 08:58:57 -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	blk-mq: provide a default queue mapping for virtio device	2017-02-27 20:54:05 +02:00
blk-mq.c	blk-mq: place trace_block_getrq() in correct place	2018-10-25 11:17:40 -06:00
blk-mq.h	blk-mq: issue directly if hw queue isn't busy in case of 'none'	2018-07-17 16:04:00 -06:00
blk-pm.c	blk-mq: Enable support for runtime power management	2018-09-26 15:11:29 -06:00
blk-pm.h	block: Split blk_pm_add_request() and blk_pm_put_request()	2018-09-26 15:11:28 -06:00
blk-rq-qos.c	blk-rq-qos: make depth comparisons unsigned	2018-07-22 11:30:53 -06:00
blk-rq-qos.h	blk-rq-qos: make depth comparisons unsigned	2018-07-22 11:30:53 -06:00
blk-settings.c	block: allow max_discard_segments to be stacked	2018-07-24 14:46:39 -06:00
blk-softirq.c	blk-mq: complete req in softirq context in case of single queue	2018-10-08 10:50:43 -06:00
blk-stat.c	block: export blk_stat_enable_accounting()	2018-09-27 17:34:54 -06:00
blk-stat.h	blk-stat: export helpers for modifying blk_rq_stat	2018-07-09 09:07:54 -06:00
blk-sysfs.c	block: Introduce blk_revalidate_disk_zones()	2018-10-25 11:17:40 -06:00
blk-tag.c	for-linus-20180616	2018-06-17 05:37:55 +09:00
blk-throttle.c	blkcg: consolidate bio_issue_init to be a part of core	2018-09-21 20:29:08 -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	blk-wbt: wake up all when we scale up, not down	2018-10-11 13:31:28 -06:00
blk-wbt.h	block: remove external dependency on wbt_flags	2018-07-09 09:07:54 -06:00
blk-zoned.c	block: Introduce blk_revalidate_disk_zones()	2018-10-25 11:17:40 -06:00
blk.h	block: Introduce blk_revalidate_disk_zones()	2018-10-25 11:17:40 -06:00
bounce.c	block: setup bounce bio_sets properly	2018-10-21 12:05:43 -06:00
bsg-lib.c	block/bsg-lib: use PTR_ERR_OR_ZERO to simplify the flow path	2018-08-01 09:13:03 -06:00
bsg.c	block: bsg: move atomic_t ref_count variable to refcount API	2018-08-27 19:17:02 -06:00
cfq-iosched.c	cfq: clear queue pointers from cfqg after unpinning them in cfq_pd_offline	2018-10-11 11:46:19 -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	This is the 4.19-rc6 release	2018-10-01 08:58:57 -06:00
genhd.c	This is the 4.19-rc6 release	2018-10-01 08:58:57 -06:00
ioctl.c	block: Introduce BLKGETNRZONES ioctl	2018-10-25 11:17:40 -06:00
ioprio.c	block: add ioprio_check_cap function	2018-05-31 10:50:54 -04:00
kyber-iosched.c	kyber: fix integer overflow of latency targets on 32-bit	2018-09-28 10:49:39 -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: use nanosecond resolution for iostat	2018-09-21 20:26:59 -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	block: move dif_prepare/dif_complete functions to block layer	2018-07-30 08:27:02 -06:00