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authorLinus Torvalds <torvalds@linux-foundation.org>2021-06-30 22:12:56 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-30 22:12:56 +0300
commitdf668a5fe461bb9d7e899c538acc7197746038f4 (patch)
tree315a71104f5cea7feeb56c9f2c768453408b72f7 /Documentation/block
parentdf04fbe8680bfe07f3d7487eccff9f768bb02533 (diff)
parent2705dfb2094777e405e065105e307074af8965c1 (diff)
downloadlinux-df668a5fe461bb9d7e899c538acc7197746038f4.tar.xz
Merge tag 'for-5.14/block-2021-06-29' of git://git.kernel.dk/linux-block
Pull core block updates from Jens Axboe: - disk events cleanup (Christoph) - gendisk and request queue allocation simplifications (Christoph) - bdev_disk_changed cleanups (Christoph) - IO priority improvements (Bart) - Chained bio completion trace fix (Edward) - blk-wbt fixes (Jan) - blk-wbt enable/disable fix (Zhang) - Scheduler dispatch improvements (Jan, Ming) - Shared tagset scheduler improvements (John) - BFQ updates (Paolo, Luca, Pietro) - BFQ lock inversion fix (Jan) - Documentation improvements (Kir) - CLONE_IO block cgroup fix (Tejun) - Remove of ancient and deprecated block dump feature (zhangyi) - Discard merge fix (Ming) - Misc fixes or followup fixes (Colin, Damien, Dan, Long, Max, Thomas, Yang) * tag 'for-5.14/block-2021-06-29' of git://git.kernel.dk/linux-block: (129 commits) block: fix discard request merge block/mq-deadline: Remove a WARN_ON_ONCE() call blk-mq: update hctx->dispatch_busy in case of real scheduler blk: Fix lock inversion between ioc lock and bfqd lock bfq: Remove merged request already in bfq_requests_merged() block: pass a gendisk to bdev_disk_changed block: move bdev_disk_changed block: add the events* attributes to disk_attrs block: move the disk events code to a separate file block: fix trace completion for chained bio block/partitions/msdos: Fix typo inidicator -> indicator block, bfq: reset waker pointer with shared queues block, bfq: check waker only for queues with no in-flight I/O block, bfq: avoid delayed merge of async queues block, bfq: boost throughput by extending queue-merging times block, bfq: consider also creation time in delayed stable merge block, bfq: fix delayed stable merge check block, bfq: let also stably merged queues enjoy weight raising blk-wbt: make sure throttle is enabled properly blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled() ...
Diffstat (limited to 'Documentation/block')
-rw-r--r--Documentation/block/bfq-iosched.rst38
1 files changed, 27 insertions, 11 deletions
diff --git a/Documentation/block/bfq-iosched.rst b/Documentation/block/bfq-iosched.rst
index 66c5a4e54130..df3a8a47f58c 100644
--- a/Documentation/block/bfq-iosched.rst
+++ b/Documentation/block/bfq-iosched.rst
@@ -553,20 +553,36 @@ throughput sustainable with bfq, because updating the blkio.bfq.*
stats is rather costly, especially for some of the stats enabled by
CONFIG_BFQ_CGROUP_DEBUG.
-Parameters to set
------------------
+Parameters
+----------
-For each group, there is only the following parameter to set.
+For each group, the following parameters can be set:
-weight (namely blkio.bfq.weight or io.bfq-weight): the weight of the
-group inside its parent. Available values: 1..1000 (default 100). The
-linear mapping between ioprio and weights, described at the beginning
-of the tunable section, is still valid, but all weights higher than
-IOPRIO_BE_NR*10 are mapped to ioprio 0.
+ weight
+ This specifies the default weight for the cgroup inside its parent.
+ Available values: 1..1000 (default: 100).
-Recall that, if low-latency is set, then BFQ automatically raises the
-weight of the queues associated with interactive and soft real-time
-applications. Unset this tunable if you need/want to control weights.
+ For cgroup v1, it is set by writing the value to `blkio.bfq.weight`.
+
+ For cgroup v2, it is set by writing the value to `io.bfq.weight`.
+ (with an optional prefix of `default` and a space).
+
+ The linear mapping between ioprio and weights, described at the beginning
+ of the tunable section, is still valid, but all weights higher than
+ IOPRIO_BE_NR*10 are mapped to ioprio 0.
+
+ Recall that, if low-latency is set, then BFQ automatically raises the
+ weight of the queues associated with interactive and soft real-time
+ applications. Unset this tunable if you need/want to control weights.
+
+ weight_device
+ This specifies a per-device weight for the cgroup. The syntax is
+ `minor:major weight`. A weight of `0` may be used to reset to the default
+ weight.
+
+ For cgroup v1, it is set by writing the value to `blkio.bfq.weight_device`.
+
+ For cgroup v2, the file name is `io.bfq.weight`.
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