Photoshop CS5.5 + Lion: Available RAM Actual RAM

Question

Hi all,
Here's my issue:
I have 24 GIGs of RAM in my machine [Mac Pro 3,1— 2.8Ghz "octo-core" (early-2008)].  I noticed recently that Photoshop was only showing 18 GIGs as available ("18544 MB" is how it's displayed in the "Performance" section of my PS Preferences)—rather than the full 24 GIGs.
I'm not positive that it is a function of my "upgrade" to Lion, but I have a strong suspicion that it is, since I am intimately familiar with my Photoshop preference settings and never noticed this issue prior to switching from Snow Leopard.
All my Adobe apps are up to date—as is my system software.  I have confirmed (via System Profiler) that my system is indeed recognizing all 24 GIGs of installed RAM.  I have had this much RAM in my machine for a long time, and under Snow Leopard, it was all recognized by Photoshop.
Questions:
- has anyone else experienced this?
- is it a bug of some sort, or a purposeful function of the OS (i.e. does Lion sequester a portion of the RAM or otherwise disallow PS to access all of it)?
Any input would be much appreciated.
-Jason

Answer 1

Chris Cox wrote:
So far we haven't seen any such difference on Lion.
This should help then...
I realized I had a hard drive with OS X 10.6 (Snow Leopard) still on it, so I booted up my Mac Pro using that drive, opened CS5 and took a look at the preferences.
Sure enough, the "Available RAM" readout is within 1 GB of the total RAM in my machine (24 GB)—which is consistent with my recollection.  I took a screen-cap of the prefs (seen on the left side of the attached image), rebooted using my current system (Lion), and fired up Photoshop CS5.5.
If you take a look at the right side of the attached image, you'll notice two things:
Right off the bat, the Available RAM in Lion is ~3 GB less than on the Snow Leopard system
The Available RAM fluctuates over time in Lion—mostly decreasing, and at one point, moving back up slightly.
I didn't spend any time in Snow Leopard to test whether the Available RAM fluctuated or not.  My recollection is that it did not—and that's based upon many months of using CS5 in Snow Leopard.  If it did fluctuate, it wasn't enough to ever catch my eye.  The fluctuation did catch my eye in Lion because of the larger and more relevant issue—the drastic decrease to the actual value(s) of Available RAM.
Losing 3 GB of RAM on a 24GB system might seem insignificant at first glance, but it's not, and here's why:
it grows to a loss of ~6GB almost immediately.
I lose another ~6GB for setting the RAM % no higher than 69% (recommended to avoid a reported memory bug)
When I spend $2,500 on software (or $10, for that matter), I have every right to expect that it won't negate several hundred dollars worth of investment into the hardware I bought to use it, unless it is advertised as such.
Wade's suggestion (faulty or incorrectly-seated RAM) crossed my mind too—even though System Profiler recognized all 24 GB with a status of "OK."  Now, it's clear that this isn't the issue.  It's also (hopefully) clear that this is a real issue, with real implications.
I have invested a lot of time, energy and money into building a high-powered system for one primary purpose—maximizing my computing power for Photoshop and Illustrator.  I have done that based upon the official documentation and recommendations of Adobe.  I run the OS and CS5.5 from a high-quality SSD, have a large, fast and dedicated scratch drive, and save my files to yet another drive.  I've been using Photoshop for 16 years, and as you may note from the scarcity of my posts, I come to this forum only as a last resort—not to waste your time or mine on frivolous issues, or to waste your time asking for explanations about issues that I can otherwise resolve on my own.
If there is an avenue other than this forum by which I can more easily achieve resolution to issues like this—by all means, please tell me where that is so I can save us all some time.  If not, then to the extent that I must come here to resolve those issues—please respect the fact that I would much rather be using the product for which I paid good money than documenting its flaws or trying to convince the company that sold it to me to listen.
Please forgive me if I sound frustrated—I am.  It's nearly 4am; I've lost a full night's work reporting this issue; and I've lost far too many additional days and nights over the last year experiencing, troubleshooting, documenting and discussing defects and quirks in CS5 (/.5)—often while feeling like I was the one on trial instead of the buggy product that I purchased.  I don't expect perfection with such robust and technical software—but I think it's reasonable to expect a supportive and attentive attitude, as well as a serious effort by the developers to fix the bugs and correct the oversights that I and others identify.
Thanks for your time.  I'm sure I'll be more cheerful on the other side of this long night.
-J