From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH] Add idle power save for ppc 4xx From: Michael Ellerman To: jyoung5@us.ibm.com In-Reply-To: <1206987598.9165.10.camel@thinkpadL> References: <10aea37177130bbe5de7.1206969157@thinkpadL> <1206983237.12155.60.camel@vader.jdub.homelinux.org> <20080331130518.2a6b0264@zod.rchland.ibm.com> <1206987598.9165.10.camel@thinkpadL> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-jLEGGen4Zyl7hVPthDej" Date: Tue, 01 Apr 2008 12:04:22 +1100 Message-Id: <1207011862.7490.5.camel@concordia.ozlabs.ibm.com> Mime-Version: 1.0 Cc: kvm-ppc-devel@lists.sourceforge.net, linuxppc-dev@ozlabs.org Reply-To: michael@ellerman.id.au List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-jLEGGen4Zyl7hVPthDej Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Mon, 2008-03-31 at 13:19 -0500, Jerone Young wrote: > On Mon, 2008-03-31 at 13:05 -0500, Josh Boyer wrote: > > On Mon, 31 Mar 2008 12:07:17 -0500 > > Josh Boyer wrote: > >=20 > > > On Mon, 2008-03-31 at 08:12 -0500, Jerone Young wrote: > > > > # HG changeset patch > > > > # User Jerone Young > > > > # Date 1206969060 18000 > > > > # Node ID 10aea37177130bbe5de7bee6ec06d9010bc5da1f > > > > # Parent 1506aa38ddabb0bf73fff3ac3f3db5f9ef6458cc > > > > Add idle power save for ppc 4xx > > > >=20 > > > > 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. > > > >=20 > > > > I have tested this on hardware & KVM virtual guest. > > >=20 > > > 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 measur= ed > > > it with an amp meter recently) and there's really no other benefit to > > > doing it outside of the virtual guest case. > > >=20 > > > 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? > >=20 > > 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. >=20 > I'll go with the Kconfig option.=20 Go with a device-tree check. The pseries kernel supports both bare-metal and hypervisor in the same kernel image, and it works out which it's running on by looking at the device-tree. This seems equivalent to me? cheers --=20 Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person --=-jLEGGen4Zyl7hVPthDej Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBH8YoWdSjSd0sB4dIRAsgZAJ0QyQ8ncxrb04jJMLutOrffcwhqnwCgwq7A yBoPtKUy6hRl9fSu3uGyrHo= =9omu -----END PGP SIGNATURE----- --=-jLEGGen4Zyl7hVPthDej--