Re: [RFC PATCH v4 00/19] Core scheduling v4

[Phil Auld]

On Fri, Mar 06, 2020 at 10:06:16AM -0800 Tim Chen wrote:
> On 3/5/20 6:41 PM, Aaron Lu wrote:
> 
> >>> So this appeared to me like a question of: is it desirable to protect/enhance
> >>> high weight task performance in the presence of core scheduling?
> >>
> >> This sounds to me a policy VS mechanism question. Do you have any idea
> >> how to spread high weight task among the cores with coresched enabled?
> > 
> > Yes I would like to get us on the same page of the expected behaviour
> > before jumping to the implementation details. As for how to achieve
> > that: I'm thinking about to make core wide load balanced and then high
> > weight task shall spread on different cores. This isn't just about load
> > balance, the initial task placement will also need to be considered of
> > course if the high weight task only runs a small period.
> > 
> 
> I am wondering why this is not happening:  
> 
> When the low weight task group has exceeded its cfs allocation during a cfs period, the task group
> should be throttled.  In that case, the CPU cores that the low
> weight task group occupies will become idle, and allow load balance from the
> overloaded CPUs for the high weight task group to migrate over.  
> 

cpu.shares is not quota. I think it will only get throttled if it has and 
exceeds quota.  Shares are supposed to be used to help weight contention
without providing a hard limit. 


Cheers,
Phil


> Tim
> 

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