Subject: [PATCH 0/8 v2] Introduce CFQ group hierarchical scheduling and "use_hierarchy" interface
Date: Monday 13th December 2010 01:44:10 UTC (over 5 years ago)
Hi Previously, I posted a patchset to add support of CFQ group hierarchical scheduling in the way that it puts all CFQ queues in a hidden group and schedules with other CFQ group under their parent. The patchset is available here, http://lkml.org/lkml/2010/8/30/30 Vivek think this approach isn't so instinct that we should treat CFQ queues and groups at the same level. Here is the new approach for hierarchical scheduling based on Vivek's suggestion. The most big change of CFQ is that it gets rid of cfq_slice_offset logic, and makes use of vdisktime for CFQ queue scheduling just like CFQ group does. But I still give cfqq some jump in vdisktime based on ioprio, thanks for Vivek to point out this. Now CFQ queue and CFQ group uses the same scheduling algorithm. "use_hierarchy" interface is now added to switch between hierarchical mode and flat mode. For this time being, this interface only appears in Root Cgroup. V1 -> V2 Changes: - Raname "struct io_sched_entity" to "struct cfq_entity" and don't differentiate queue_entity and group_entity, just use cfqe instead. - Give newly added cfqq a small vdisktime jump accord to its ioprio. - Make flat mode as default CFQ group scheduling mode. - Introduce "use_hierarchy" interface. - Update blkio cgroup documents [PATCH 1/8 v2] cfq-iosched: Introduce cfq_entity for CFQ queue [PATCH 2/8 v2] cfq-iosched: Introduce cfq_entity for CFQ group [PATCH 3/8 v2] cfq-iosched: Introduce vdisktime and io weight for CFQ queue [PATCH 4/8 v2] cfq-iosched: Extract some common code of service tree handling for CFQ queue and CFQ group [PATCH 5/8 v2] cfq-iosched: Introduce hierarchical scheduling with CFQ queue and group at the same level [PATCH 6/8] blkio-cgroup: "use_hierarchy" interface without any functionality [PATCH 7/8] cfq-iosched: Add flat mode and switch between two modes by "use_hierarchy" [PATCH 8/8] blkio-cgroup: Document for blkio.use_hierarchy. Benchmarks: I made use of Vivek's iostest to perform some benchmarks on my box. I tested different workloads, and didn't see any performance drop comparing to vanilla kernel. The attached files are some performance numbers on vanilla Kernel, patched kernel with flat mode and patched kernel with hierarchical mode.