linux-kernel - Re: [PATCH 0/8 v2] Introduce CFQ group hierarchical scheduling and "use

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Message-ID: <4D062161.4010300@kernel.dk>
Date:	Mon, 13 Dec 2010 14:36:33 +0100
From:	Jens Axboe <axboe@...nel.dk>
To:	Gui Jianfeng <guijianfeng@...fujitsu.com>
CC:	Vivek Goyal <vgoyal@...hat.com>,
	Corrado Zoccolo <czoccolo@...il.com>,
	Chad Talbott <ctalbott@...gle.com>,
	Nauman Rafique <nauman@...gle.com>,
	Divyesh Shah <dpshah@...gle.com>,
	linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/8 v2] Introduce CFQ group hierarchical scheduling and
 "use_hierarchy"  interface

On 2010-12-13 02:44, Gui Jianfeng wrote:
> 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.

I was going to apply this patchset now, but it doesn't apply to current
for-2.6.38/core (#5 fails, git am stops there). Care to resend it
against that branch? Thanks.

-- 
Jens Axboe

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