Commit 82861595 authored by Kir Kolyshkin's avatar Kir Kolyshkin Committed by Jens Axboe
Browse files

docs/cgroup-v1/blkio: update for 5.x kernels 



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 795fe54c 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.

Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarKir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 37fe4038

Documentation/admin-guide/cgroup-v1/blkio-controller.rst

+16 −15
Original line number Diff line number Diff line
@@ -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