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Gmane
From: Gui Jianfeng <guijianfeng <at> cn.fujitsu.com>
Subject: [PATCH 0/8 v2] Introduce CFQ group hierarchical scheduling and "use_hierarchy" interface
Newsgroups: gmane.linux.kernel
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.
 
CD: 4ms