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Date:      Mon, 27 Feb 2017 19:15:58 +0000
From:      bugzilla-noreply@freebsd.org
To:        freebsd-acpi@FreeBSD.org
Subject:   [Bug 217247] [acpi] r265474 makes 11.0R unusable with Atom 330
Message-ID:  <bug-217247-13733-PyBGutnBud@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-217247-13733@https.bugs.freebsd.org/bugzilla/>
References:  <bug-217247-13733@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D217247

--- Comment #4 from St=C3=A9phane Lesimple <stephane_freebsd@lesimple.fr> -=
--
(In reply to Adrian Chadd from comment #2)

Compiled HEAD this morning, namely base r314326 and booted it.
It does behave differently: at boot I couldn't observe the slowdown.

However after some digging, I found out that HEAD's /etc/default/rc.conf is
different and now contains:

> performance_cx_lowest=3D"NONE"

Where 11.0R contained

> performance_cx_lowest=3D"Cmax"

(introduced by base r265474)

On my system, NONE translates to C1, as shown by sysctl -a, so that's why it
behaves properly: it never tries to use C2 or C3.

I tried to manually set dev.cpu.X.cx_lowest to C2, and see if the slowdown =
was
still there, but it wasn't. However sysctl indicates that my setting is
completely ignored and the system always uses C1, as seen by cx_usage:

dev.cpu.0.cx_method: C1/hlt C2/io C3/io
dev.cpu.0.cx_usage_counters: 4617 0 0
dev.cpu.0.cx_usage: 100.00% 0.00% 0.00% last 49467us
dev.cpu.0.cx_lowest: C2
dev.cpu.0.cx_supported: C1/1/0 C2/2/1 C3/3/85
dev.cpu.0.%parent: acpi0
dev.cpu.0.%pnpinfo: _HID=3Dnone _UID=3D0
dev.cpu.0.%location: handle=3D\_PR_.P001
dev.cpu.0.%driver: cpu
dev.cpu.0.%desc: ACPI CPU

So this *is* indeed different from 11.0R. For some reason the kernel now
chooses to keep C1 at all times, even if I tell it that C2 is okay. If you =
want
me to try anything, just ask, I'm keeping HEAD's memstick.img around just in
case.

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