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

[Tim Chen]

On 1/14/20 7:43 PM, Li, Aubrey wrote:
> On 2020/1/14 23:40, Vineeth Remanan Pillai wrote:
>> On Mon, Jan 13, 2020 at 8:12 PM Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> wrote:
>>
>>> I also encountered kernel panic with the v4 code when taking cpu offline or online
>>> when core scheduler is running.  I've refreshed the previous patch, along
>>> with 3 other patches to fix problems related to CPU online/offline.
>>>
>>> As a side effect of the fix, each core can now operate in core-scheduling
>>> mode or non core-scheduling mode, depending on how many online SMT threads it has.
>>>
>>> Vineet, are you guys planning to refresh v4 and update it to v5?  Aubrey posted
>>> a port to the latest kernel earlier.
>>>
>> Thanks for the updated patch Tim.
>>
>> We have been testing with v4 rebased on 5.4.8 as RC kernels had given us
>> trouble in the past. v5 is due soon and we are planning to release v5 when
>> 5.5 comes out. As of now, v5 has your crash fixes and Aubrey's changes
>> related to load balancing.
> 
> It turns out my load balancing related changes need to be refined.
> For example, we don't migrate task if the task's core cookie does not match
> with CPU's core cookie, but if the entire core is idle, we should allow task
> migration, something like the following:
> 
> I plan to do this after my Chinese New Year holiday(Feb 3rd).
> 
> Thanks,
> -Aubrey
> 

Aubrey's attached patch should replace his previous patch
sched/fair: don't migrate task if cookie not match

I've also added a fix below for Aubrey's patch
sched/fair: find cookie matched idlest CPU.  

Aubrey, can you merge this fix into that patch when you update
your patches?

Tim

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