Re: suspend and hibernate nomenclature

[David Brownell <david-b@pacbell.net>]

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On Thursday 18 May 2006 1:50 pm, Pavel Machek wrote:

> Well, will it ever go to sleep? In such case? There are many things
> that wake up periodically.

Applications that constantly wake/poll are death to power management anyway,
that's not news ... most of the "work" done by polling is wasted.  When they
get switched to no-timeout/blocking APIs, then they can sleep painlessly
until a relevant wakeup event triggers.

Things that really *must* wake up periodically should be using some API that
interacts with RTC alarms, and those RTC alarms should be acting as system
wakeup events.


There's also non-automated sleep too ... what "apmsleep" used to do when
you told it to suspend until 7am (or for two hours, etc).  The same thing
can be done with /sys/power/state and a wakeup-enabled RTC.


> > As for downloading, that's why ethernet adapters have wake-on-lan (WOL)
> > mechanisms.  Likewise for other wakeup-capable devices, like a keyboard
> > or mouse.  Or even 3D engines, DSPs, SPUs, ...
> 
> ?? WOL is for different functionality, I'm afraid. Or do you know
> ethernet hub that automagically wakes machines when data come?

No, that's exactly what WOL is designed for.  A typical scenarios has
the adapter waking up when the incoming packet is unicast to the MAC
address of that host.  The hub/switch would act normally.

- Dave

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