3.75 GB of 4 GB @ MPB w/ discrete GPU

Yes, it reports the same 3.75 GBs regardless of GPU. This is definitely a bug in the OS. Ether the OS is not releasing the shared memory or Activity Monitor is failing to report the correct information.

You have no idea if the problem won't be solved in a future system update or upgrade. Perhaps it will be different in Lion. I'm sure you aren't the only person concerned. This is an old topic that dates back to the first dual-GPU MBPs. You would know that if you searched the forums. In fact look under the "More like this" section at the top of this topic. 🙂

I'd say that this can not be "solved" or "addressed" becoase it is not a bug, but say architectural change.

1) Hardware devices memory mapping goes on very low level during hardware initialisation during boot process - so memory regions, mapped to hardware, can not be "freed" as easily as usual memory regions, it takes special measures. Its more like wired than used memory

2) Apple everywhere uses unified architectural approach.

3) All the new hardware just does not release that memory becoase of "on-the-fly" GPU switching - and it looks like a way for years ahead.

4) Highly unprobable that Apple will research some special, not-unified approach exclusively for out-of-production hardware

I'd say that if possibility to regain shared memory evaporated in line with start of sales of "on-the-fly" switching MBPs - it will not return, becoase it shows that it was some deep architectural change in graphics drivers subsystem at least.

Look, there are a lot of such things, for example - combined 32/64 binary use more HD space, I don't need 32 part, but it just exists - it's architectural thing. It gives Mac OS more flexibility and, in the end, better experience for Mac users. For a price of some space waste. Same situation with that memory - more flexible OS - but with a price of less optimal resource usage in some situations.

Nothing to fix, you see it?

I'd say that if possibility to regain shared memory evaporated in line with start of sales of "on-the-fly" switching MBPs...

It didn't. Since the release of the very first MBP models that had two GPUs, that possibility has never existed — unless it has been introduced in very recent models.

The rest of your post may be correct; I don't know.

Whatever gave you the idea you hurt my feelings? No such thing. Just stated what the situation is, that's all. 🙂

I know, I should check it myself before post )

eww, I based my assumption on Kappy post where he stated that it worked before. After your post I decided to recheck the thing - so here we go:

I was partially wrong and we all have good news )

MBP 5.2 (17 in, gf 9600/9400, 4 Gb ram) under Lion GM (sorry, only system I have at home) shows:

boot in economy mode (ie GF 9400 shared 256 Mb ram) - total 4 Gb , wired ~725 Mb, active ~485 Mb, used total - ~1.25 Gb, free total - ~2.75 Gb

switch to performance mode - ie GF 9600 512 Mb onboard - logout-login - same picture

BUT performance mode with reboot - woila - total 4 Gb, wired - ~570 Mb, active - ~427 Mb, used total - ~1.03 Gb, free - ~ 2.95 Gb

So here it is - regained shared memory, but only after reboot. Just upgrade to Lion, and that precios 250 Mb is yours )

I really was too pessimistic

ps. and it didn't work on MBP 8.3 (2011), just checked the thing.

Message was edited by: dm_dimon