svn commit: r264250 - head/sys/dev/acpica
jhb at freebsd.org
Tue Apr 8 13:37:39 UTC 2014
On Monday, April 07, 2014 10:36:27 pm Adrian Chadd wrote:
> Author: adrian
> Date: Tue Apr 8 02:36:27 2014
> New Revision: 264250
> URL: http://svnweb.freebsd.org/changeset/base/264250
> Add a basic set of data points which count the number of sleep entries
> that are being done by the OS.
> For now this'll match up with the "wakeups"; although I'll dig deeper into
> this to see if we can determine which sleep state the CPU managed to get
> into. Most things I've seen these days only expose up to C2 or C3 via
> ACPI even though the CPU goes all the way down to C6 or C7.
No, those are actually the same thing. ACPI and Intel both use C-states for
the same thing, but the numbers don't line up. That is, Intel's C6/C7 gets
exposed to the OS as C2/C3 via ACPI. The 6/7 does matter, (I think) if you
are using monitor/mwait as I believe the value you configure for an mwait
sleep has to use Intel's number (6/7) whereas the ACPI number (2/3) is
assigned by the results of _CST or whichever object it is ACPI queries.
All that to say that ACPI is already using Intel's C6/C7 if you have
configured your BIOS to expose it.
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