Re: [patch v5 04/15] sched: add sched balance policies in kernel

Alex Shi
2013-02-21T01:42:51Z

On 02/20/2013 11:41 PM, Ingo Molnar wrote:
>
> * Alex Shi <alex.shi@intel.com> wrote:
>
>> Now there is just 2 types policy: performance and
>> powersaving(with 2 degrees, powersaving and balance).
>
> I don't think we really want to have 'degrees' to the policies
> at this point - we want each policy to be extremely good at what
> it aims to do:
>
> - 'performance' should finish jobs in in the least amount of
> time possible. No ifs and whens.
>
> - 'power saving' should finish jobs with the least amount of
> watts consumed. No ifs and whens.
>
>> powersaving policy will try to assign one task to each LCPU,
>> whichever the LCPU is SMT thread or a core. The balance policy
>> is also a kind of powersaving policy, just a bit less
>> aggressive. It will try to assign tasks according group
>> capacity, one task to one capacity.
>
> The thing is, 'a bit less aggressive' is an awfully vague
> concept to maintain on a long term basis - while the two
> definitions above are reasonably deterministic which can be
> measured and improved upon.
>
> Those two policies and definitions are also much easier to
> communicate to user-space and to users - it's much easier to
> explain what each policy is supposed to do.
>
> I'd be totally glad if we got so far that those two policies
> work really well. Any further nuance visible at the ABI level is
> I think many years down the road - if at all. Simple things
> first - those are complex enough already.

Thanks for comments!
I will remove the 'balance' policy.

>
> Thanks,
>
> Ingo
>

--
Thanks Alex