From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joanna Rutkowska Subject: Passive and Active ACPI Thermal control under Xen? Date: Wed, 13 Jul 2011 17:31:30 +0200 Message-ID: <4E1DBA52.6070002@invisiblethingslab.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0750527755==" Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --===============0750527755== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigBD2A04F03DBFC4443652D0DD" This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigBD2A04F03DBFC4443652D0DD Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hello, With summer in full swing these days, I've been trying to somehow cool down my laptop, which brought me into tinkering with various ACPI stuff, and raised a few questions on how Xen and Dom0 cooperate to enforce thermal policy. I'm using Xen 4.1 booted *without* cpufreq=3Ddom0-kernel and I can see xenpm returning all the various info about my processors' C and P states. I can even set the policy, e.g.: xenpm set-scaling-gov powersave The only problem being it has absolutely zero impact on the system temperature... According to the ACPI spec, there are two primary methods for thermal control of the platform: 1) active control and 2) passive control. The former works by OSPM enabling various fans at different speeds, depending on the measured temperatures from various sensors, while the latter works by throttling down the CPU frequencies and perhaps by controlling transitions to the deeper C states. My understanding is that the cpufreq mechanism in Xen is essentially an implementation of the passive thermal control? If this is so, does Xen honor the ACPI-defined _TC1 and _TC2 constants (that one usually can set in the BIOS)? I could imagine that this should be the correct behavior when one selects the 'powersave' governor, shouldn't it? Next question relates to the active thermal control -- who is in charge of spinning the fans? My understanding is that on a baremetal Linux, this is the job of the thermal.ko module? (which also apparently should take care about the passive control, although not when booted under Xen) Unfortunately I cannot get my cooling fan to spin :( I tried setting the temp thresholds in BIOS for when the fan should be spinning at low and high speed (_AC0, _AC1), and even pass them directly to the thermal.ko module (as 'act' param), but my fan remain silent even though I can see the temperature going above the thresholds. The only moment I can hear my fan spinning at full speed is during early boot stage (I assume this is when the _AC0, _AC1 constants I set in BIOS are actually honored by the SMI handler), but then, after booting into Xen and Dom0 the fan is being turned off. Xen 4.1.0, Dom0 kernel: 2.6.38 (xenlinux), platform: Sony Vaio Z12 Thanks, joanna. --------------enigBD2A04F03DBFC4443652D0DD Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJOHbpSAAoJEDaIqHeRBUM08N4H/iQPZj42EfLWdigkzZQfCsqV gecDa2d7WT65zrT2o3BD6ftzIe8Nf6JVaFjmYivmp2/y5vmxFaxIBR+kM6XLI1T1 N9Ib5fx90T4oRUMyyt0kvnBhYHa2i6Op06bK4FOs53XBLd+hEe91NvbRqLmFnSmh GmZzoPgv18GGuZLHCJ2R1j6RKvccmsD5o1pB9AXjctf4D2Hf8OTdfOYXPW7uzpYo AGYqpGbkhqa/mvNveGnD9c7aCo9qHhCjOZjLkyjLgyFwMgV1bPdQ5eCnsLVfcgea PVuw/f9GD2AF3QYvt5FskbxD267YH65O6s+o84AcnA/yiK4KJWYbY7TnL2tNk9s= =zPV9 -----END PGP SIGNATURE----- --------------enigBD2A04F03DBFC4443652D0DD-- --===============0750527755== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --===============0750527755==--