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[0/1] bfq: remove prefixes from cgroup filenames

Message ID 20190408143935.9062-1-paolo.valente@linaro.org
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Series bfq: remove prefixes from cgroup filenames | expand

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Paolo Valente April 8, 2019, 2:39 p.m. UTC 
When bfq was merged into mainline, there were two I/O schedulers that
implemented the proportional-share policy: bfq for blk-mq and cfq for
legacy blk. bfq's interface files in the blkio/io controller have the
same names as cfq. But the cgroups interface doesn't allow two
entities to use the same name for their files, so for bfq we had to
prepend the "bfq" prefix to each of its files. However no legacy code
uses these modified file names. This naming also causes confusion, as,
e.g., in [1].

So we tried to propose a solution to enable entities to share
interface files for identical parameters [2]. But our solution didn't
convince Tejun, and we got stuck.

Fortunately, now cfq has gone with legacy blk, so there is no need any
longer for prefixes in (the never used) bfq names. In view of this
fact, here's an alternative patch, which simply removes these
prefixes, thereby enabling legacy code to truly use the proportional
share policy in blk-mq. This postpones the problem of sharing common
interface files, to when, e.g., some new proportional-share policy
gets proposed.

Paolo

[1] https://github.com/systemd/systemd/issues/7057
[2] https://lwn.net/ml/linux-block/20181119103424.3853-1-paolo.valente@linaro.org/

Angelo Ruocco (1):
  block, bfq: delete "bfq" prefix from cgroup filenames

 block/bfq-cgroup.c | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

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2.20.1