On Mon, 31 Mar 2008 12:07:17 -0500 Josh Boyer <[EMAIL PROTECTED]> wrote:
> On Mon, 2008-03-31 at 08:12 -0500, Jerone Young wrote: > > # HG changeset patch > > # User Jerone Young <[EMAIL PROTECTED]> > > # Date 1206969060 18000 > > # Node ID 10aea37177130bbe5de7bee6ec06d9010bc5da1f > > # Parent 1506aa38ddabb0bf73fff3ac3f3db5f9ef6458cc > > Add idle power save for ppc 4xx > > > > This patch sets the wait state MSR when power_save is called in cpu_idle > > loop for ppc4xx. This is mainly to help out virtualization solutions such > > as KVM. This way the virtualization soultions are able to tell if the guest > > kernel is idle. > > > > I have tested this on hardware & KVM virtual guest. > > I'm not overly thrilled with adding this to all of 4xx. It doesn't > actually save much power at all (1% on a project that actually measured > it with an amp meter recently) and there's really no other benefit to > doing it outside of the virtual guest case. > > I'm assuming you pass a dtb to the virtual guest when you start it up. > Could you define a property in the CPU node there that can be parsed to > use the power_save function instead of always making it the default? Actually, you probably don't want this as a property in the device tree. It doesn't describe hardware. A Kconfig option might be warranted though. josh _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
