Re: [RFC][PATCH 1/2] ARM64: add cpu topology definition

Vincent Guittot
2013-07-29T10:28:26Z

On 29 July 2013 12:15, Sudeep KarkadaNagesha
<Sudeep.KarkadaNagesha@arm.com> wrote:
> On 29/07/13 10:46, Vincent Guittot wrote:
>> On 27 July 2013 12:42, Hanjun Guo <hanjun.guo@linaro.org> wrote:
>>> Power aware scheduling needs the cpu topology information to improve the
>>> cpu scheduler decision making.
>>
>> It's not only power aware scheduling. The scheduler already uses
>> topology and cache sharing when CONFIG_SCHED_MC and/or
>> CONFIG_SCHED_SMT are enable. So you should also add these configs for
>> arm64 so the scheduler can use it
>>
> Just for my knowledge, I thought power aware using SCHED_MC/SMT was
> removed. I see commit 8e7fbcbc22c12414bcc9dfdd683637f58fb32759 "sched:
> Remove stale power aware scheduling remnants and dysfunctional knobs"
> I may be missing something here.

It's a common mistake to mixed SCHED_MC and powersaving balance with
SCHED_MC. Only the powersaving policy has been removed but the
SCHED_MC and SCHED_SMT are always in the scheduler and gives perf
improvement on arm 32bits

>
> Regards,
> Sudeep
>