Re: shrinking memory for suspend?

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > > Which is why the powermac/powerbook sleep code insists on there only
> > > being one cpu active.  I have an SMP powermac which can sleep; I use a
> > > little script to take the second cpu down before sleeping and bring it
> > > back up after waking up.
> > 
> > That's quite intrusive.  Ideally, user space processes should not notice that
> > there have been a suspend at one point.
> 
> Certainly, *most* userspace processes should not notice, and they
> don't.  But the process initiating the suspend most certainly knows
> about the suspend happening.  And that's the one that arranges for
> taking the second cpu down and bringing it up.  So your objection
> seems silly to me, unless you meant something other than what your
> words seem to say.

Not silly at all.

xterm #1						xterm #2

suspend-to-RAM					
script does echo 0 > CPU1/online as part of process	echo 0 > CPU1/online

If this happens, resume will most likely online CPU1, contrary to
user's commands.

Plus, if your script is bad and leaves other CPUs running, you
get rather nasty oops, or worse. Userspace should not be able to crash
kernel like _that_.
									Pavel
-- 
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