Messages in this thread | | | Date | Fri, 11 Feb 2011 17:58:49 +0800 | From | Gui Jianfeng <> | Subject | Re: [PATCH 0/6 v4] cfq-iosched: Introduce CFQ group hierarchical scheduling and "use_hierarchy" interface |
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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, >> 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 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?
Hi Vivek,
I did fio test by runing 8 threads with different ioprio. It seems patched kernel and vanilla kernel act the same behaviour. That is it doesn't play well. As I metioned in previous mail, when I disable idling, all threads become SYNC_NOIDLE, and then preempt each other, even if I start 8 threads. And reposition at the top of service tree. This's why we can't see service differetiation.
> > 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. > > 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.
Ok, I'd like to take a look chad's patch.
Thanks Gui > > Thanks > Vivek >
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