Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig

[bsegall]

Yuyang Du <yuyang.du@xxxxxxxxx> writes:

> On Tue, Sep 15, 2015 at 10:11:41AM -0700, bsegall@xxxxxxxxxx wrote:
>> >
>> > I guess you are saying we are conflating NICE_0 with NICE_0_LOAD. But to me,
>> > they are just integer metrics, needing a resolution respectively. That is it.
>> 
>> Yes this would change nothing at the moment post-expansion, that's not
>> the point. SLR being 10 bits and the nice-0 being 1024 are completely
>> and utterly unrelated and the headers should not pretend they need to be
>> the same value,
>
> I never said they are related, why should they be related. And they need or
> need not to be the same value, fine.
>
> However, the SLR has to be a value. It is because it mighe be 10 or 20 (LOAD),
> therefore I make SCHED_RESOLUTION_SHIFT 10 (kind of a denominator). Not the
> other way around.
>
> We can define SCHED_RESOLUTION_SHIFT 1, and then define SLR = x * SCHED_RESOLUTION_SHIFT
> with x being a random number, if you must.

That's sorta the point - you could do this and it would be just as (non-)sensical.

>
>> any more than there should be a #define that is shared
>> with every other use of 1024 in the kernel.
>
> The point really is, metrics (if not many ) need resolution, not just NICE_0_LOAD does. 
> You can choose to either hardcode a number, like SCHED_CAPACITY_SHIFT now,
> or you can use SCHED_RESOLUTION_SHIFT, which is even as simple as a sign to say what
> the defined is (the scaled one with a better resolution vs. the original one).
> I guess this is to say we now have a (no-big-deal) resolution system.

Yes they were chosen for similar reasons, but they are not conceptually
related, and you couldn't decide to just bump up all the resolutions by
changing SCHED_RESOLUTION_SHIFT, so doing this would just be misleading.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/