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Date:      Mon, 12 Jul 2010 08:40:36 -0700
From:      Jeremy Chadwick <freebsd@jdc.parodius.com>
To:        Markus Gebert <markus.gebert@hostpoint.ch>
Cc:        freebsd-stable <freebsd-stable@freebsd.org>, John Baldwin <jhb@freebsd.org>
Subject:   Re: 8.1-RC2 - PCI fatal error or MCE triggered by USB/ehci on Sun X4100M2?
Message-ID:  <20100712154036.GA13481@icarus.home.lan>
In-Reply-To: <4615FFAA-F78B-475E-B40B-CC33791F1D23@hostpoint.ch>
References:  <6B57591F-9FA2-45EB-825F-1DB025C0635D@hostpoint.ch> <201007120851.35529.jhb@freebsd.org> <0CF6CF2B-907C-42EF-B57E-DF50F0564455@hostpoint.ch> <201007121106.59454.jhb@freebsd.org> <4615FFAA-F78B-475E-B40B-CC33791F1D23@hostpoint.ch>

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On Mon, Jul 12, 2010 at 05:23:23PM +0200, Markus Gebert wrote:
> 
> On 12.07.2010, at 17:06, John Baldwin wrote:
> 
> > Are you using Cx states other than C1 for the CPUs at all?
> 
> Not sure how to find out, but I did not change anything in the BIOS settings (if even possible) or through sysctl regarding cpu idle modes. Anyway, here's what I found:
> 
> # sysctl machdep.idle machdep.idle_available
> machdep.idle: amdc1e
> machdep.idle_available: spin, amdc1e, hlt, acpi, 
> 
> Not sure if "amdc1e" qualifies for something "other than C1". I tried "hlt" once, which didn't make a difference IIRC. And if that's not what you needed, here's more:
> 
> # sysctl dev.cpu
> [...]
> dev.cpu.0.freq_levels: 2786/95000 2587/81800 2388/69811 2189/58977 1990/49240 1791/44316 995/22525
> dev.cpu.0.cx_supported: C1/0
> dev.cpu.0.cx_lowest: C1
> [...]

cx_supported indicates your CPU only supports C1 and not lower
power-saving states (C2/C3/C4, etc.).  Non-C1 states can sometimes do
"interesting" things when it comes to interrupt handling.  I believe
your system may support the C1E state (given what machdep.idle_available
shows), but that's often controlled by the system BIOS (on both Intel
and AMD processors, but I'm trying to focus on AMD here).  C1E, as far
as I know, is the same as C1 state except can save a little bit more
power.

I believe neither C1 nor C1E do anything with interrupts, instead just
halting the core when idle/not in use.  HLT mode, at least on multi-core
AMD CPUs, equates to C1E.

Shot in the dark: you're not running powerd(8) on this system are you?

-- 
| 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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