Re: [TuxOnIce-devel] [RFC] TuxOnIce

[Rafael J. Wysocki]

On Wednesday 27 May 2009, Oliver Neukum wrote:
> Am Dienstag, 26. Mai 2009 00:58:53 schrieb Rafael J. Wysocki:
> > > No, I am afraid it is not. The average user has no clue. Even if that
> > > is not the problem, the user never knows for sure he has encountered
> > > the worst case.
> >
> > OK there, but surely it's better to have a sysfs attribute than a fixed
> > value?
> 
> Maybe I should have been more verbose.
> 
> A tunable setting is a race condition in itself. The right amount depends
> on the drivers loaded and the devices attached and possibly on the status
> of devices. Nothing of this can be determined statically.
> 
> You want hibernation to work even if the user has plugged in a new device.
> You have to calculate that amount in kernel space.

In practice, though, the drivers don't usually tell us in advance how much
memory they are going to need and I believe the only way they could do that
would be by allocating the memory from a hibernation notifier.

So, until the drivers start to use hibernation (and suspend for that matter)
notifiers, we need workarounds.

Best,
Rafael
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