H-BFQ: Supporting Multi-Level Hierarchical Cgroup in BFQ Scheduler

In current Linux systems, the BFQ scheduler has become the de-facto standard I/O scheduler that supports Cgroup. However, it cannot guarantee I/O proportionality when cgroups compose a multi-level hierarchy, because BFQ disregards the hierarchical relationship among the cgroups. To solve this problem, we propose a hierarchy-aware BFQ, called H-BFQ, which calculates the relative I/O proportion of each cgroup by traversing the entire Cgroup tree and distribute the I/O resources to the cgroups according to their I/O proportions. Experimental results demonstrate that H-BFQ guarantees I/O proportionality of the multi-level hierarchical Cgroup with negligible overhead.