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

[bsegall]

Yuyang Du <yuyang.du@xxxxxxxxx> writes:

> On Fri, Sep 11, 2015 at 10:05:53AM -0700, bsegall@xxxxxxxxxx wrote:
>> 
>> SCHED_LOAD_RESOLUTION and the non-SLR part of SCHED_LOAD_SHIFT are not
>> required to be the same value and should not be conflated.
>  
>> In particular, since cgroups are on the same timeline as tasks and their
>> shares are not scaled by SCHED_LOAD_SHIFT in any way (but are scaled so
>> that SCHED_LOAD_RESOLUTION is invisible), changing that part of
>> SCHED_LOAD_SHIFT would cause issues, since things can assume that nice-0
>> = 1024. However changing SCHED_LOAD_RESOLUTION would be fine, as that is
>> an internal value to the kernel.
>>
>> In addition, changing the non-SLR part of SCHED_LOAD_SHIFT would require
>> recomputing all of prio_to_weight/wmult for the new NICE_0_LOAD.
>
> Not fully looked into the concerns, but the new SCHED_RESOLUTION_SHIFT
> is intended to formalize all the integer metrics that need better resolution.
> It is not special to any metric, so actually it is to de-conflate whoever is
> conflated.

It conflates the userspace-invisible SCHED_LOAD_RESOLUTION with the
userspace-visible value of scale_load_down(NICE_0_LOAD). Increasing
SCHED_LOAD_RESOLUTION must not change scale_load_down(NICE_0_LOAD).
--
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/