swsusp limits

swsusp limits

[Randy.Dunlap]

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Hi Pavel,

Is there a maximum system RAM size that is supported by swsusp?

Does swsusp (to disk) use only one swap partition or can it use
multiple swap partitions (aggregate them into one logical space)?

Is there an option or possibility of using a dedicated swap
partition for suspend to disk?
Or maybe there is no reason to think that this might help?

If my application(s) causes lots of memory & swap space
to be used (over half of the total system RAM), is it correct
that it is likely to be useless to try to suspend to disk
while that app is running?
or should I try to use suspend2 instead?

Thanks,
-- 
~Randy

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Re: swsusp limits

[Pavel Machek]

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Hi!

> Is there a maximum system RAM size that is supported by swsusp?

It should work okay with highmem.

> Does swsusp (to disk) use only one swap partition or can it use
> multiple swap partitions (aggregate them into one logical space)?

Only one swap partition, sorry.

> Is there an option or possibility of using a dedicated swap
> partition for suspend to disk?
> Or maybe there is no reason to think that this might help?

I don't see how it could help.

> If my application(s) causes lots of memory & swap space
> to be used (over half of the total system RAM), is it correct
> that it is likely to be useless to try to suspend to disk
> while that app is running?

No, it should work okay, as long as you do not mlock() it. Just prepare
big enough swap partition.

[I'll add your questions to FAQ...]
								Pavel
-- 
if you have sharp zaurus hardware you don't need... you know my address

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Re: Re: swsusp limits

[Nigel Cunningham]

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Hi

On Tue, 2005-08-09 at 08:07, Pavel Machek wrote:
> > Is there an option or possibility of using a dedicated swap
> > partition for suspend to disk?
> > Or maybe there is no reason to think that this might help?
> 
> I don't see how it could help.

If it was turned on at the right time, it might not be used by other
things that could get swapped out by high memory usage and/or the memory
eating process.

> > If my application(s) causes lots of memory & swap space
> > to be used (over half of the total system RAM), is it correct
> > that it is likely to be useless to try to suspend to disk
> > while that app is running?
> 
> No, it should work okay, as long as you do not mlock() it. Just prepare
> big enough swap partition.

Will he even need to worry about the size of his swap partition? I
though swsusp discarded everything it could anyway. (Perhaps you could
add this question to the FAQ too).

Regards,

Nigel

> [I'll add your questions to FAQ...]
> 								Pavel
-- 
Evolution.
Enumerate the requirements.
Consider the interdependencies.
Calculate the probabilities.


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Re: Re: swsusp limits

[Pavel Machek]

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Hi!

> > > Is there an option or possibility of using a dedicated swap
> > > partition for suspend to disk?
> > > Or maybe there is no reason to think that this might help?
> > 
> > I don't see how it could help.
> 
> If it was turned on at the right time, it might not be used by other
> things that could get swapped out by high memory usage and/or the memory
> eating process.

Yes, but if it is used all the time, it will work okay, too.

> > > If my application(s) causes lots of memory & swap space
> > > to be used (over half of the total system RAM), is it correct
> > > that it is likely to be useless to try to suspend to disk
> > > while that app is running?
> > 
> > No, it should work okay, as long as you do not mlock() it. Just prepare
> > big enough swap partition.
> 
> Will he even need to worry about the size of his swap partition? I
> though swsusp discarded everything it could anyway. (Perhaps you could
> add this question to the FAQ too).

If he has *lot* of data, he needs big swap partition. Of course,
everything I _can_ discard will be discarded.

This is what I ended up:
							Pavel

diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt
--- a/Documentation/power/swsusp.txt
+++ b/Documentation/power/swsusp.txt
@@ -334,3 +334,18 @@ some kind of "really read-only!" option.
 image (and blocksize), with resume parameter pointing directly to
 suspend header.
 
+Q: Is there a maximum system RAM size that is supported by swsusp?
+
+A: It should work okay with highmem.
+
+Q: Does swsusp (to disk) use only one swap partition or can it use
+multiple swap partitions (aggregate them into one logical space)?
+
+A: Only one swap partition, sorry.
+
+Q: If my application(s) causes lots of memory & swap space to be used
+(over half of the total system RAM), is it correct that it is likely
+to be useless to try to suspend to disk while that app is running?
+
+No, it should work okay, as long as your app does not mlock() it. Just
+prepare big enough swap partition.


-- 
if you have sharp zaurus hardware you don't need... you know my address

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