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From: Gui Jianfeng <>
To: Vivek Goyal <>, Chad Talbott <>
Cc: Jens Axboe <>, Shaohua Li <>,
	lkml <>,
	Divyesh Shah <>
Subject: Re: [PATCH 0/6 v4] cfq-iosched: Introduce CFQ group hierarchical scheduling and "use_hierarchy" interface
Date: Sat, 12 Feb 2011 14:08:54 +0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Vivek Goyal wrote:
> On Thu, Feb 10, 2011 at 03:45:45PM +0800, 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,
>> 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 use the same scheduling algorithm. 
>> "use_hierarchy" interface is now added to switch between hierarchical mode
>> and flat mode. It works as memcg.
>> --
>> V3 -> V4 Changes:
>> - Take io class into account when calculating the boost value.
>> - Refine the vtime boosting logic as Vivek's Suggestion.
> Hi Gui,
> What testing did you do to make sure that this vtime boosting logic is working
> and is good replacement for slice_offset() logic for cfqq?
> Secondly, did you get a chance to look at chad's patch of keeping track
> of previous assigned vdisktime and keeping track of genrations. I think
> his patch is going to coflict with yours, so one of you will have to
> make adjustments. I think both the boost logic and keeping track of generation
> logic can be combined.

Hi Vivek,

For the time being, boosting logic only works for cfq queue, and keepinging track of
generation works for cfq group.
I think when we introduce boosting logic for cfq group, we can combine these two logic


> 	if (entity->gneration_number > cfqd->active_generation)
> 		Use_boost_logic;
> 	else
> 		Use_previously_assigned_vdisktime;
> That way if we generation has changed then we really don't have a valid
> vdisktime and we can use boost logic to come up with differential
> vdisktime and if generation has not changed then we can continue to make
> use of previous vdisktime.
> Thanks
> Vivek
> --
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  parent reply	other threads:[~2011-02-12  6:09 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-10  7:45 Gui Jianfeng
2011-02-10 18:30 ` Vivek Goyal
2011-02-11  9:58   ` Gui Jianfeng
2011-02-12  6:08   ` Gui Jianfeng [this message]
2011-02-14 18:06     ` Vivek Goyal
2011-02-15  3:13       ` Gui Jianfeng
2011-02-15 14:29         ` Vivek Goyal

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