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Date:      Sat, 30 Apr 2011 21:20:28 -0700
From:      Jeremy Chadwick <freebsd@jdc.parodius.com>
To:        freebsd-stable@freebsd.org
Cc:        jkim@freebsd.org
Subject:   Is machdep.cpu_idle_hlt deprecated?
Message-ID:  <20110501042028.GA87381@icarus.home.lan>

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Anyone know if machdep.cpu_idle_hlt still exists?  Taken from acpi(4) on
RELENG_8:

   hw.acpi.cpu.cx_lowest
	Lowest Cx state to use for idling the CPU.  A scheduling algo-
	rithm will select states between C1 and this setting as system
	load dictates.  To enable ACPI CPU idling control,
	machdep.cpu_idle_hlt must be set to 1.

$ sysctl -d machdep.cpu_idle_hlt
sysctl: unknown oid 'machdep.cpu_idle_hlt'

I'm taking a stab in the dark here, but it looks like the variable no
longer exists because it's been replaced with, effectively, the
framework that drives machdep.idle and machdep.idle_available
(specifically the mwait_hlt and hlt methods).  Doing "grep -r
cpu_idle_hlt /usr/src" turns up nothing other than the cpu_idle_hlt()
functions that live within machdep.c per architecture, and those (based
on the code) correlate with what's shown in machdep.idle_available.

If I'm correct, I believe that means we can safely remove the last line
of text in the acpi(4) man page?

There's also a mention of this variable in a file called
src/tools/tools/sysdoc/tunables.mdoc, but I'm not sure what that is.

-- 
| Jeremy Chadwick                                   jdc@parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.               PGP 4BD6C0CB |




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