Impacts of disabling Automatic Power Management

[Sridhar Dhanapalan]

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.

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