Hi Jens, have you had time to look into this? Thanks, Paolo > Il giorno 21 mag 2019, alle ore 10:01, Paolo Valente <paolo.valente@xxxxxxxxxx> ha scritto: > > Many userspace tools and services use the proportional-share policy of > the blkio/io cgroups controller. The CFQ I/O scheduler implemented > this policy for the legacy block layer. To modify the weight of a > group in case CFQ was in charge, the 'weight' parameter of the group > must be modified. On the other hand, the BFQ I/O scheduler implements > the same policy in blk-mq, but, with BFQ, the parameter to modify has > a different name: bfq.weight (forced choice until legacy block was > present, because two different policies cannot share a common parameter > in cgroups). > > Due to CFQ legacy, most if not all userspace configurations still use > the parameter 'weight', and for the moment do not seem likely to be > changed. But, when CFQ went away with legacy block, such a parameter > ceased to exist. > > So, a simple workaround has been proposed by Johannes [1] to make all > configurations work: add a symlink, named weight, to bfq.weight. This > pair of patches adds: > 1) the possibility to create a symlink to a cgroup file; > 2) the above 'weight' symlink. > > Thanks, > Paolo > > [1] https://lkml.org/lkml/2019/4/8/555 > > Angelo Ruocco (2): > cgroup: let a symlink too be created with a cftype file > block, bfq: add weight symlink to the bfq.weight cgroup parameter > > block/bfq-cgroup.c | 6 ++++-- > include/linux/cgroup-defs.h | 3 +++ > kernel/cgroup/cgroup.c | 33 +++++++++++++++++++++++++++++---- > 3 files changed, 36 insertions(+), 6 deletions(-) > > -- > 2.20.1
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