Currently for sched_mc_power_savings, we use the topology information derived from the physical/core/thread ID's.
Thanks, suresh -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Martin Wilck Sent: Tuesday, February 26, 2008 6:28 AM To: Pallipadi, Venkatesh; [email protected] Subject: Re: [Discuss] _CSD support Pallipadi, Venkatesh wrote: > _CSD is the way BIOS coomunicates the C-state dependencies across cores > in the system. The way _CSD is defined, OS communicates with BIOS about > its capability through _PDC or _OSC and BIOS can then return methods > like _PSD and _CSD. > _CSD is not supported in Linux right now. > Having said that, _CSD is not really interesting on Intel CPUs at this > time as C-states are hardware coordinated. That means, OS can make each > CPU enter C-state independently (assuming each core is independent) and > hardware will do the required coordination underneath. Yes, but from what I gathered, power savings will only be significant (at least on Quad CPUs) if the OS puts all cores in a package to sleep at the same time. sched_mc_power_savings=1 tries to do exactly that - but how does Linux determine which Cores belong to a package, if _CSD is unsupported? Just by sibling/phys core ID ? Martin -- Martin Wilck PRIMERGY System Software Engineer FSC IP ESP DE6 Fujitsu Siemens Computers GmbH Heinz-Nixdorf-Ring 1 33106 Paderborn Germany Tel: ++49 5251 8 15113 Fax: ++49 5251 8 20209 Email: mailto:[EMAIL PROTECTED] Internet: http://www.fujitsu-siemens.com Company Details: http://www.fujitsu-siemens.com/imprint.html _______________________________________________ Discuss mailing list [email protected] http://mail.lesswatts.org/mailman/listinfo/discuss _______________________________________________ Discuss mailing list [email protected] http://mail.lesswatts.org/mailman/listinfo/discuss
