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Subject: Re: RFC: setting performance_cx_lowest=C2 in -HEAD to avoid lock
 contention on many-CPU boxes
From: "K. Macy" <kmacy@freebsd.org>
To: Adrian Chadd <adrian@freebsd.org>
Cc: freebsd-arch@freebsd.org
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Um, don't you care more about power savings when it's on battery?
On Apr 25, 2015 10:44 AM, "Adrian Chadd" <adrian@freebsd.org> wrote:

> Oh the other thing, which I just mentioned to kip in IRC - all of the
> intel laptops I've tested (and that's a long list) don't enter CPU C7
> if the power is plugged in.
>
> Ie:
>
> * power in, ACPI C2 -> CPU C6
> * power in, ACPI C3 - CPU C6
> * battery - ACPI C2 -> CPU C6
> * battery -> ACPI C3 -> CPU C7
>
> So having performance_cx_lowest=C3 is effectively a no-op on the
> devices that it'd matter on, so it's okay to just flip it to C2.
>
>
>
> -adrian
>