Commit bf382fb0bcef4 ("block: remove legacy IO schedulers", Oct 12 2018)
removes the CFQ scheduler, together with blkio.weight and
blkio.weight_device described in cgroup v1 documentation. Users are
supposed to use the BFQ scheduler, which cgroup file for setting weight
is blkio.bfq.weight, but there is no way to set per-device weight.
Later, commit 795fe54c2a8 per-device weights for BFQ, meaning that
blkio.bfq.weight and blkio.bfq.weight_device can be used in a way
similar to the old CFQ cgroup interface.
Yet, the cgroup v1 docs were never updated. Fix this:
- use the new file names;
- fix the range for weight (used to be 10..1000, now 1..1000);
- link to BFQ scheduler docs.
Signed-off-by: Kir Kolyshkin <kolyshkin@xxxxxxxxx>
---
.../cgroup-v1/blkio-controller.rst | 31 ++++++++++---------
1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/Documentation/admin-guide/cgroup-v1/blkio-controller.rst b/Documentation/admin-guide/cgroup-v1/blkio-controller.rst
index 8101dcba381d..16253eda192e 100644
--- a/Documentation/admin-guide/cgroup-v1/blkio-controller.rst
+++ b/Documentation/admin-guide/cgroup-v1/blkio-controller.rst
@@ -97,40 +97,41 @@ Details of cgroup files
Proportional weight policy files
--------------------------------
- blkio.weight
+ blkio.bfq.weight
Specifies per cgroup weight. This is default weight of the group
- on all the devices until and unless overridden by per device rule.
- (See blkio.weight_device).
- Currently allowed range of weights is from 10 to 1000.
+ on all the devices until and unless overridden by per device rule
+ (see `blkio.bfq.weight_device` below).
- blkio.weight_device
- One can specify per cgroup per device rules using this interface.
- These rules override the default value of group weight as specified
- by blkio.weight.
+ Currently allowed range of weights is from 1 to 1000. For more details,
+ see Documentation/block/bfq-iosched.rst.
+
+ blkio.bfq.weight_device
+ Specifes per cgroup per device weights, overriding the default group
+ weight. For more details, see Documentation/block/bfq-iosched.rst.
Following is the format::
- # echo dev_maj:dev_minor weight > blkio.weight_device
+ # echo dev_maj:dev_minor weight > blkio.bfq.weight_device
Configure weight=300 on /dev/sdb (8:16) in this cgroup::
- # echo 8:16 300 > blkio.weight_device
- # cat blkio.weight_device
+ # echo 8:16 300 > blkio.bfq.weight_device
+ # cat blkio.bfq.weight_device
dev weight
8:16 300
Configure weight=500 on /dev/sda (8:0) in this cgroup::
- # echo 8:0 500 > blkio.weight_device
- # cat blkio.weight_device
+ # echo 8:0 500 > blkio.bfq.weight_device
+ # cat blkio.bfq.weight_device
dev weight
8:0 500
8:16 300
Remove specific weight for /dev/sda in this cgroup::
- # echo 8:0 0 > blkio.weight_device
- # cat blkio.weight_device
+ # echo 8:0 0 > blkio.bfq.weight_device
+ # cat blkio.bfq.weight_device
dev weight
8:16 300
--
2.31.1
