[conspire] idle computer

Tue Jul 12 16:32:48 PDT 2011

On Tue, Jul 12, 2011 at 04:08:19PM -0700, Rick Moen wrote:
> Quoting Ruben Safir (ruben at mrbrklyn.com):
> 
> > I believe he is talking about the suspend action, which is now built
> > into the gnome interface allong with everything else it should do.
> 
> I see, on attempting to re-parse what Paul asked that -- in talking
> about a computer being 'idle' or 'not in use' -- in _some_ places he's
> talking about the OS or ACPI controller chip putting the computer into
> sleep/suspend-to-RAM or hiberation/suspend-to-disk mode, and sometimes
> he's talking about the screensaver kicking in, and some process
> associated with the screensaver (e.g., SETI at home) kicking in.
> 
> Those are two rather different things.
> 
> The two separate programs called 'SETI at home' for Linux are both
> proprietary packages, capable of either running whenever the screensaver
> kicks in or alternatively in background continuously whever the
> computer's active and the user is logged in.  The earlier program is
> more accurately named 'SETI at home Classic' and did only SETI.  Its late
> 2005 replacement is Berkeley Open Infrastructure for Network Computing
> (BOINC), which runs whatever distributed computing projects it's
> directed to remotely by the scientists at UC Berkeley's Space Sciences
> Laboratory.
> 
> Neither of those programs is particularly related to the process of an
> ACPI-aware OS, or the ACPI controller chip acting on its own, deciding
> to put the host machine into sleep or hibernate mode.
> 
> Paul wrote:
> 
> [He installed LMDE, and:]  
> > After I had answered all of the questions and saw that files were
> > being copied, I walked away and expected it would be done when I got
> > back. I returned to a black display. I wiggled the mouse and I saw
> > that files were still copying.
> 
> The 'black display' seems to refer to something having blanked the
> screen.  Paul is more than a bit unclear as to whether or not the files
> were copying while the screen was blanked.  

Right, but you have to assume, know that you can always be wrong, that
since he is mentioning the copying of files, that this is likely failing
(or wy mention it), and that would be due to a suspend to ram or disk.

If he is using gnome, he can turn that off, or turn it off within the
system admin toolkit of whatever distro he is using.

>He should have been able to
> determine the answer to that question by listening to hard drive
> activity.

I tend to feel for the fan to be on or off.

> 
> Obviously, none of us is likely to be able to tell Paul exactly what was
> going on with his machine, as we weren't there, and his recounting has
> big holes in it.  It's likely that either the screen alone was blanked,
> or that the screen was blanked and the system as a whole slept or
> hibernated.  Which one?  Can't say.  Wasn't there.  Don't know the
> particulars of Paul's system.
> 
> > Are ACPI settings written by Windows stored where they would effect
> > the Linux install?
> 
> This seems like a very unfocussed question that rests on a wild guess
> about how ACPI works.

Its completely unfocused.  But good money is on the fact that gnome or
kde is the admin of the suspend mode.

> 
> ACPI is a horribly overfeatured specification for power management and
> device configuration that was developed for x86 machines (but not, say, 
> PowerPC ones) by a consortium that included Intel, Microsoft, and
> several laptop and BIOS companies.  Additionally, as horribly mangled
> and byzantine as the specification is, it's also marred by pervasive
> manufacturer-specific proprietary extensions.  Thus, because they're
> unwilling to develop proprietary code under NDA, the Linux kernel coders
> are put in a position of having to reverse-engineer a significant part
> of the necessary hardware support.
> 

And yet my dell opteron seems to handle it better than I've seen any
other system do so before.  Too bad its my new server and I'll have to
kill the feature.

> Speaking generally, once an ACPI-compliant operating system boots, 
> it informs the ACPI controller chip of its presence and informs the chip
> that it's taking over hardware + power management.  This control over
> the system includes when and if to go into sleep or hibernate, and
> switching among full-performance and lower-performance/power-saving
> operating modes.  This situation persists until restart.  I _think_ 
> the system reverts to its BIOS-set settings at the time of restart.
> At which point, an ACPI-compliant operating system may boot and say 'I'm
> taking over' again.
> 
> > Why does a computer that is busy copying files think it is 'not in
> > use'?
> 
> I interpret this question as intending to ask:  'Why would a supposedly
> ACPI-aware OS put a machine into a mode with the screen blanked and with
> little or no computing power available, while a bulk file-copy is
> underway?'
> 
> Again, it is unclear from Paul's description whether the screen was
> _merely_ blanked or whether hard disk activity had also been halted.
> (Paul, don't forget that your knowledge of how your system _sounds_ is
> an important diagnostic tool.)  It is unclear whether his system went
> into sleep / suspend-to-RAM 'S3' mode.  (MS-WIndows's 'hiberate' command
> is associated with ACPI mode S3.)  It is unclear whether his system
> went into hibernate / suspend-to-disk 'S4' mode.  It is unclear whether 
> the system merely blanked the screen and used voltage/frequency CPU
> scaling to enter a lower-power P1 to P16 power-saving mode.  It is
> unclear whether the system blanked the screen and put the CPU into a
> powered-on but halted S1 'stopgrant' mode.  (MS-Windows's 'standby'
> command reportedly puts system ACPI into mode S1.)  It is unclear
> whether the system blanked the screen and put most devices into
> power-off via ACPI mode S5 'soft off' mode.  (MS-Windows's 'shutwon'
> command puts system ACPI into mode S5.)
> 
> In any event, FWIW, when the Linux kernel's ACPI code does any of these
> things, it changes the record of system state under /sys/power/state.
> I'd speculate that it probably also makes entries under /var/log,
> somewhere.
> 
> If the result was the kernel doing something dumb, then why did it do
> something dumb?  Could be broken or manufacturer-proprietary things in
> the system BIOS firmware that the kernel didn't understand correctly.

My guess, and I'm being ignorant, is that as long as not keyboard or
mouse movent happens, it goes to sleep, regardless of any other
functions.

> Could be actual inadequacies in how your version of the kernel attempts
> to implement the inscrutable and byzantine ACPI specification.  Could be
> that you're running cruddy proprietary hardware drivers (e.g., Nvidia)
> that work only poorly with the kernel.  Could be that some ACPI kernel
> modules aren't loaded.  (See:
> https://wiki.archlinux.org/index.php/ACPI_modules )
> 
> Could be that the manufacturer's DSDT (Differentiated System Description
> Table) is inscrutable and incomplete, and should be replaced by a better
> one.  See:  https://wiki.archlinux.org/index.php/DSDT
> 
> To see how insanely complicated ACPI support can get, see this
> troubleshooting guide: http://en.gentoo-wiki.com/wiki/ACPI/Fix_common_problems
> About controlling Linux's supervision of CPU frequency scaling, see
> this:  http://rffr.de/acpi
> 
> 
> I suspect that Paul's other questions are largely addressed by the
> above.
> 
> 
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