Date: Sat, 25 Apr 2015 11:02:09 -0700 From: "K. Macy" <kmacy@freebsd.org> To: Adrian Chadd <adrian@freebsd.org> Cc: freebsd-arch@freebsd.org Subject: Re: RFC: setting performance_cx_lowest=C2 in -HEAD to avoid lock contention on many-CPU boxes Message-ID: <CAHM0Q_N0h2khSSQwpAmqV361N2e%2BsB4pFg5MTO8%2BtQNzZGmDdg@mail.gmail.com> In-Reply-To: <CAJ-VmokhS7KLxq0fVRjDaR3naEMORei07=49SoiP2bSQXog8WQ@mail.gmail.com> References: <CAJ-VmonG%2By5gzoYmer70KAswUorvezcZxRSDsQWj47=jsAZ71w@mail.gmail.com> <CAHM0Q_NuvZH0GGs-J9xniyt2PZ0qb_kjOaanVOaCxzD0CVzGYg@mail.gmail.com> <CAJ-Vmo=6ej6b52yoknP_piL5uJYHm_1AxZh7=6AFGuqMO4sLVg@mail.gmail.com> <CAJ-VmokhS7KLxq0fVRjDaR3naEMORei07=49SoiP2bSQXog8WQ@mail.gmail.com>
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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 >
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