Impacts of disabling Automatic Power Management

Paul Fox pgf at laptop.org
Wed Feb 8 22:38:43 EST 2012


sridhar wrote:
 > On 5 February 2012 10:12, Sridhar Dhanapalan <sridhar at laptop.org.au> wrote:
 > > On 5 February 2012 02:35, Martin Langhoff <martin.langhoff at gmail.com> wrote:
 > >> On Sat, Feb 4, 2012 at 10:26 AM, Samuel Greenfeld <greenfeld at laptop.org> 
 > wrote:
 > >>> Disabling suspend during collaboration was discussed a year ago, but as far
 > >>> as I know this has not made it into any 11.3.x build:
 > >>> http://dev.laptop.org/ticket/10363
 > >>
 > >> Thanks for that! I had forgotten ~
 > >>
 > >> Sridhar, Jerry -- that bug has a patch that implements exactly the
 > >> Sugar change I was proposing.
 > >>
 > >> We later dropped it for a change to powerd that we thought would cover
 > >> all the bases by relying on using wake-on-LAN on the wlan... which we
 > >> later learned is somewhat buggy.
 > >>
 > >> Please test with this patch and let us know whether it helps.
 > >
 > > Thanks! We'll add this to our next dev build.
 > 
 > In our next build, we will be doing two things [1]:
 > 
 >   1. enabling the patch
 >   2. disabling wake-on-LAN
 > 
 > It seems to me that this is the preferred solution. I think we only
 > need to inhibit power management when collaboration is active, not for
 > any LAN traffic.
 > 
 > Living up to its name, wake-on-LAN keeps the XOs awake whenever a
 > network connection is active, even when you don't really need it to
 > be. Assuming that it always works as intended (which as you have
 > explained, it does not), the patch won't be very testable when it is
 > active.

i guess you're saying that an active network connection should be
keeping the laptop awake, and therefore being able to wake it up after
it sleeps is a moot point.  that may be true for chatty collaboration
protocols -- it certainly wouldn't be true for TCP sessions (which isn't
your use case -- i understand that).

but in addition, without wake-on-lan, a sleeping laptop will be
invisible to its peers, at least until the user wakes it up.  is that
okay?

paul

 > 
 > erikos reckons that the patch won't do much [2], but the testing
 > performed so far seems to be small-scale. Hopefully we'll get some
 > feedback on this after we put out our build.
 > 
 > Sridhar
 > 
 > 
 > [1] https://dev.laptop.org.au/issues/1049
 > [2] http://dev.laptop.org/ticket/10363#comment:21
 > 
 > 
 > 
 > Sridhar Dhanapalan
 > Engineering Manager
 > One Laptop per Child Australia
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 > Devel at lists.laptop.org
 > http://lists.laptop.org/listinfo/devel

=---------------------
 paul fox, pgf at laptop.org


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