[Ti] Weird Screen Behavior...

[David Remahl]

On Thursday, March 6, 2003, at 08:52 AM, b wrote:

> According to Michael Bigley:
>
>>> The problem is thus: I go to transform a layer. I do a command T, 
>>> adjust the layer to the size I want it at, and hit enter. At that 
>>> moment (when it resamples the layer) the screen goes "hysteric" and 
>>> jumps around for a few seconds. I have never seen this behavior 
>>> before, and it has only happened in Photoshop, when working with a 
>>> layer. I should also mention I only have 1GB of free space on my 
>>> disk.
>>
>> The amount of free space is very small and could cause that weird 
>> behavior in Photoshop.  I don't think Adobe has the OSX memory scheme 
>> perfected in PS 7.x.  I would imagine that the OS and PS are fighting 
>> over that gig.
>
> Sort of. The OS 'takes' the space it needs, mostly for the Swap, right 
> from the get-go. That's why a 30 GB drive, on a Mac with 1 GB RAM 
> shows total space of 28,75 GB or so. The OS reserves double the 
> physical RAM, probably. half for itself, half for OS 9's VM. Just a 
> guess, but nothing else would really make sense.

I am fairly sure that this is incorrect. The OS does not allocate 2x 
the amount of RAM on boot on the hard drive, nor does it reserve that 
space. It always creates one swap file, and the default size of those 
is 80MB. If later, the physical RAM and the swap file is not 
sufficient, it goes on to create more 80 MB swap files. If it doesn't 
succeed in doing so, all hell will break loose! Well, maybe what 
happens isn't _that_ dramatic, but it will cause problems and erratic 
behaviour. Rebooting may well be the only solution if it goes far 
enough.

Secondly, Classic is Just Another Process as far as the operating 
system is concerned. Classic believes that it has 1GB of physical RAM, 
and its memory is managed like all other applications' by Mac OS X.

> Where Photoshop is concerned, all P-Shop users know that it wants as 
> much space as you'll give it for a 'scratch' disk. A partition is 
> nice, because it can be erased or whatever, after projects are 
> completed... giving Photoshop nice clean drive space to do its thing 
> in. But it functions fine, as long as there is sufficient free space, 
> and the less-fragmented, the better.

> I run a lot of apps over here, audio/visual/ and tons of the usual. 
> There are only two apps [actually, one app, and a 'Suite'] that never 
> crash on me: Photoshop, and Office for Mac OSX. Everything else takes 
> its turn giving itself the heave-ho. My experience is that Adobe 
> P-Shop  runs great in Jag.

Heh...That's funny. Those two applications are the only ones that crash 
regularly on my machine :-). Well, there are a few others that do it 
too, but very seldom. Word crashes as soon as I touch it (which is why 
I don't :) and Photoshop crashes every once in a while.

In conclusion, running Mac OS X with less than 1 GB of hard disk space 
is a BadThing. Having less than 400MB free (which Photoshop could 
certainly cause with its internal disk swap) - is a ReallyBadThing, and 
is known to cause the system to forget preferences. With even less 
space available, you risk the whole system, in case it runs out of VM 
(an ExtremelyBadThing).

/ Rgds, David Remahl