Ideal Memory Allocation?

Jeff Schewe, Adobe Photoshop expert, offers us the facts on Photoshop, Jeff writes:

Read this: Photoshop CS2-How much RAM? – Fact
< http://photoshopnews.com/2005/04/04/photoshop-cs2-how-much-r am-fact/>

When you get done and understand it, try reading: Memory allocation and usage (Photoshop CS2) <http://www.adobe.com/support/techdocs/320005.html/>

And then read:
Improve performance in Photoshop CS2 on computers with more than 1 GB RAM <http://www.adobe.com/support/techdocs/331372.html/>

GB gives you good advice. That’s very good reading.

You need to understand what "available memory" is and why your question could (should) be phrased differently.

The answer depends on many factors. If you had 8GB of RAM installed, you could set your memory allowance at 100%. If you only had 1GB, you would have to shoot for 50% or less.

In the meantime, with 1.5GB installed, set it at 60%-70% or so, and you’ll be fine.

The key is to leave enough RAM for the OS, any auxiliary applications and a little headroom.

70% should work.

Many thanks all for the excellent guidance. I do like the idea of leaving the activity monitor on and checking that vs. the native Pshop efficiency guage.

Leaving Activity Monitor (AM) running means that you are allocating ram and CPU cycles to an another application rather than Photoshop. Given the size of your images and the relatively low amount installed I would suggest that switch AM off; therefore making better use of the little you have.

Another good place for info on allocating ram and speeding up photoshop is: <http://www.macgurus.com/>. Click on photoshop acceleration and download the pdf. Inside that file you will also find a link to a photoshop test file that can help you fine tune all of your settings for the typical file sizes you work with.

I have read the above links but am still not 100% sure whether I should be setting my allocation to 100% or 70% even though I have 6GB physical RAM on G5 dual PPC 2.3 with MacOS 10.4.8. I understand most of the terminology but not all of it.

When I set CS2 to 100% I had the impression it slowed, but there might be other reasons that Im not aware of for that which were just coincidence, e.g. some app might have just decided to access the web for a software update in the background, or Safari might be hanging in the background ( again!) etc. I generally keep open apps to a minimum but cannot be sure what caused what , yet.

The advice, as I understand it, says that with a G5 PPC with over 4GB Ram (I have 6GB) you can set the memory allocation to 100%, but it doesn’t say you SHOULD, just you CAN.

I have also read about removing the tilde from disabling large tiles and the VM buffering plug in, which I will try.

However I wish somewhere it told me what I SHOULD do for my configuration not what I might like to do if I fancied the idea, because I really don’t know enough to know whether Im making a fully informed decision or not.

I am mostly working from RAW files of about 12mb (Canon 5D) and there are about 2000 of those for bridge to cope with as well ( I know I know _ I really should get my image collection better organised)
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Thank goodness this type of recurring thread will be a thing of the past in CS3. 😀

Paul,

No one can tell you what you SHOULD do.

If I had 6GB of RAM, I’d set it at 90%.

No one can tell me what I should do? Why on earth not?

Surely Adobe, who make the program after all, can tell me what one should do with a given configuration for best performance? If not that would mean everyone was just guessing! Are you telling me that everyone is just guessing. i.e. it’s a process of trial and error?

Because no one, not even Adobe knows what type of files you work with, what other applications you may run at the same time, what your CPU usage is, etc.

It is indeed a process of common sense tied with a little trial and error.

First, you need to get over the concept of "allocation". It’s an "allowance", if anything, and it refers to a continuously, dynamically changing percentage of available memory, NOT of installed RAM.

Setting it at 90% of available memory would mean that, in your case, with 6GB of RAM, you would allow Photoshop to use up to 90% of available memory which is what you would have left after the OS and any other application(s) or invisible process(es) are running at a given time have grabbed what memory they need.

It DOES NOT mean you are setting 5.4GB of RAM aside for Photoshop to use, not at all.

It means only that Photoshop is allowed to use as much as it needs up to 90% of what is available at any given time. That figure (available memory) changes dynamically every fraction of a second.

Now, despite being allowed to grab up to 90% of the available memory, Photoshop will NEVER use more than its limit imposed by two factors, (a) the limit imposed by a 32bit OS, which is 2^31 [one bit is reserved] minus some overhead, so it works out to just a little under 2GB, AND (b) a workaround the Adobe engineers found to let Photoshop use a little more than what the OS allows in Tiger 10.4.x (not Panther 10.3.x), which works out to a just a little over 3GB.

Now, if you were to set your Photoshop memory allowance at 50%, thinking it would work to 3GB, it would in actuality work out to less than 3GB because it’s 50% of available memory not 50% of RAM. If for any reason, you were using 2GB of RAM between the OS and other running processes, your available memory would be only 4GB, and Photoshop would be allowed to use only 50% of that, which would work out to 2GB.

Photoshop will NEVER use more than what it needs at any given moment. The memory "allowance" is only the maximum it is allowed to use.

Once again, for the last time: If I had 6GB of RAM, I’d set it at 90%.

I would then watch and see if a minor correction were in order (which I doubt). No one can see what my machine is doing better than I can, and no one can see what your machine is doing better than you.

Things like the number and type of open fonts, the number of Widgets (I have disabled Dashboard alltogether because my machine is maxed out at 2GB of RAM), Spotblight (also disabled in my case), and many other factors have an impact on your dynamically changing available memory, which varies every fraction of a second.

And with that, I’m out of here. Anyone else, please feel free to jump in. I have run out of ideas on how to explain this to a belligerent poster.

Paul,

In case you have not realized it, you are NOT addressing Adobe here in these user to user forums. We are all users just like you, trying to help each other out.

Click here <http://www.adobeforums.com/cgi-bin/webx?50@@.2cd06cd9> for advice on how to ask your question correctly for quicker answers. Thanks!

WOW!!!
you sure took me the wrong way!