On 5/21/19 2:01 AM, Paolo Valente wrote: > 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. Applied, thanks. -- Jens Axboe
