MacBook Pro Does Not Support Both GPUs Simultaneously

[NovapaX]

You are well informed but you cannot read. I commented the following statement: "real SLI (using graphics power from both cards simultaneously) requires about the same performance for each graphics chip."

I see, that was indeed not true, we agree on that point then

on-topic:
Looking at available info from NVIDIA I think this is a harware limitation. There quite a few technical caveats with this technology.
(Did some quick reading on wikipedia and took a quick look at the Tech Brief from NVIDIA, it's complicated and it doesn't 'just work' )

 

[Chilz0r]

I believe you are right.
real SLI (using graphics power from both cards simultaneously) requires about the same performance for each graphics chip.

I think the log-out log-in issue will be solved with a software update, and it looks like nvidia knows a little bit more about 10.5.6 than we do.....

I really don't know if it is possible that 'Grand Central' in snow leopard can use the graphics chip not in use, but i suspect it would be possible and it is developed with this update in mind.

That kinda makes sense because you don't see anybody putting an 8800GT and an 8600GT in SLi do you? They have to be the same type of card.

 

[namethisfile]

Sure but not CUDA.

right. because CUDA is for NVIDIA. my assumption, though, is that opencl or grand central or both that will be in snow leopard will make use of the gpu's for general computer tasks on the get go regardless of what gpu or how old they are. in essence, making an iMac, for example, have extra cores due to the gpu becoming an auxilary cpu. and, this would be reflected in the activity monitor where you see two of the intel cores and maybe six or seven or eight, or however many cores that are in the gpu. am i correct or in the ballpark with this assumption? also, how will CUDA be implemented in MAC environment? and what is the difference between CUDA and OPENCL?

 

[cantthinkofone]

WHAT!

Then it's not SLI.....So you log out of OS X, and then what? Do a key command more complicated than clearing the PRAM and hold one foot in the air?

 

[ageha]

That kinda makes sense because you don't see anybody putting an 8800GT and an 8600GT in SLi do you? They have to be the same type of card.

I can't believe someone just wrote that...

 

[mgclayton]

I'm finding all of this a little strange. It's as if being able to hot swap GPU is a vital piece of functionality we can't live without!

Why not look at it like this? The new MBP has a smaller more efficient chipset (which also has a bonus integrated GPU), faster FSB 1066MHz, faster DDR3 RAM, and a faster discrete GPU. Excellent, and you still get 4 hours battery life.

Why would you need/want to use the integrated graphics ever?
Maybe you're going on a long trip and not doing anything intensive, e.g. letting the kids watch DVDs in the back of the car, OK, enable the integrated graphics and leave it for the trip. Extra battery life, what a bonus!

Why do you suddenly NEED to hot swap when you've never done so before? To show your mates how cool it is?

 

[iMacmatician]

I think the reason for not supporting both GPUs at once is because the resultant heat and power consumption would be too high.

Or am I missing something?

Sounds right to me.

Watching the log files on my MBP, it appears that OS X stops aqua (as well as many processes dependent on it) when swapping between GPUs. This may be resolved with either a new Kernal, or implementation of Aqua that can fully offload graphics processes to memory (not sure if that is possible??) while the switch occurs.

Having a "multi layered" OS has some limitations I guess.

Maybe Snow Leopard will fix it?

 

[Mechcozmo]

Oh, my. What is it with you people?

Apple is not a dumb company. They know what they are doing. Requiring a log-out/log-in is not the Apple way of working, but I can assure you, the code required to even switch between two GPUs without anything running on them is terribly complex. To do such a thing on the fly is even more complicated. I'm willing to bet that Snow Leopard will tie a lot of loose ends together for these machines.

Let's look at this list: Linkety

The only "con" that requires extensive hardware changes to fix would be the re-addition of FireWire. (I am in favour of that, by the way, and to see another FW port on the Pros... a second 800 would be nice, as if you have a 400 device you end up bringing the entire bus down)

The $99 adapter for 30" displays will be less of an issue when the 30" display gains DisplayPort connections. By the way, anyone else see the incredible parallels between ADC and DisplayPort? Power, USB/Data, and Digital Signaling all in one...

CPU speeds will increase over time. Sure, they didn't go up much now. Wait for a Rev. B if you actually need those extra performance points. But for the vast majority of users, those processors will be perfectly acceptable, and this "con" is more of a "it'd have been nice to see" vs. "it really sucks that"

The Trackpad pane is a software fix, like the GPUs are.

And I feel like the 17" MacBook Pro isn't going to be phased out, but that's just me. There is certainly some uncertainty about it. More than likely, it's just getting manufacturing down and Apple had to go to the event without it. Either way, we'll get our answer pretty soon.

 

[Fidgetyrat]

I don't give a damn about any SLI

What needs to be fixed is the log out. No reason for that and I hope it addressed in a future update.

 

[iMacmatician]

CPU speeds will increase over time. Sure, they didn't go up much now. Wait for a Rev. B if you actually need those extra performance points.

The current $1299 MacBook has the exact same clock speed as the original $1299 MacBook 2 and a half years ago.

 

[dwdrums]

I believe you are right.
real SLI (using graphics power from both cards simultaneously) requires about the same performance for each graphics chip.

That is why Nvidia calls it Hybrid SLI.

 

[mac jones]

Vmware virtual machine with it's own GPU would run native?

(except for sound etc..)

 

[astubbs]

man that sux. knowing me i'll never end up using the faster gpu! ugh. i'm certainly not going to be forced to log out - this reminds me of the windows days of restarting after every change!
yeah - hopefully they'll upgrade this feature in the near future with better software support.

Honesty logging out is not such a big deal

maybe not for you, but it is for me! you should see how much stuff I have going on at once in my work environment. I hate restarting my work environment. --- see above.

 

[Phil A.]

I'm finding all of this a little strange. It's as if being able to hot swap GPU is a vital piece of functionality we can't live without!

Why not look at it like this? The new MBP has a smaller more efficient chipset (which also has a bonus integrated GPU), faster FSB 1066MHz, faster DDR3 RAM, and a faster discrete GPU. Excellent, and you still get 4 hours battery life.

Why would you need/want to use the integrated graphics ever?
Maybe you're going on a long trip and not doing anything intensive, e.g. letting the kids watch DVDs in the back of the car, OK, enable the integrated graphics and leave it for the trip. Extra battery life, what a bonus!

Why do you suddenly NEED to hot swap when you've never done so before? To show your mates how cool it is?

QFT
Apple could simply have disabled the integrated graphics and not given the option at all (as with the previous MBPs). Instead they include it as a low power option which you can use if you really need to maximize battery life and you'd think they'd committed genocide by some of the comments on here
Personally, if I got one of the new MBPs I can't imagine a scenario where I'd want to switch to the integrated graphics as the discrete card gives plenty of battery power...

 

[sra. Aguirre]

Sweet! Yet another to my list to wait with buying a new MBP for a year or so. Still I can not let go of the feeling that they rushed into things with these new MBP's..... but I might be wrong...

 

[Erwin-Br]

What a bizarre point of view. You write off the entire notebook range because you can't be arsed to spend a few seconds logging out and in again to swap GPUs? How do you react when Software Update demands you reboot your machine - a process that likely takes LONGER than swapping the GPU?

User FAIL.

Bizarre point of view? You do realize that PC's and Windows have been ridiculed and mocked for less?

 

[strikeinsilence]

Kind of a bummer, but not a huge surprise. I agree with everyone about the logout, it's oh so very un-apple.

 

[Voidness]

I don't think it was implied during the keynote that the MacBook Pro would be able to use both GPUs simultaneously, so what's the outrage about?

The current $1299 MacBook has the exact same clock speed as the original $1299 MacBook 2 and a half years ago.

True, but the bus speed and RAM bandwidth did improve since the first MacBook. The CPU also got a 64-bit upgrade and more cache memory.

 

[riversky]

I was thinking, besides the screen size and max hard drive (1TB) with the new 15inch MacBook Pro you essentially have the most powerful iMac in a portable form. Add the 24inch monitor and for a few hundred dollars more you have a complete desktop system and the portable. I think that is an awesome setup.

 

[Padraig]

Kind of a bummer, but not a huge surprise. I agree with everyone about the logout, it's oh so very un-apple.

Especially when you consider the new sony laptops can switch cards with a flick of a switch.

 

[Baron58]

What needs to be fixed is the log out. No reason for that

Really?? So you're a hardware-driver programmer? Please enlighten us as to WTF *you* are smarter than then engineers who actually worked on it? You seem to be so enlightened, you could go start your own computer company in your garage, name it after some fruit, and show Apple, Inc. how it *ought* to be done.

 

[steve-p]

The $99 adapter for 30" displays will be less of an issue when the 30" display gains DisplayPort connections.

Not if you've already got your 30" display it won't. To add insult to injury, the adapter says something like 'ships in 4-6 weeks' on the UK store. So they now require users to buy an expensive adapter AND fail to make it even available at launch, excellent work.

 

[fastbite]

Looks like those macbook pros are very disappointing. The only things going for them are design and, if you care, their new production methods.

There is no innovation at all. The only reason one would have to update is the new trackpad and an under utilized graphics card.

More and more I am tempted to switch to a PC. I like the OS X a lot better than windows, and I am used to some applications on the Mac. But having to use their overpriced pieces of older technology is truly irritating.

There's an incredible hardware world out there, maybe not always as stylish, but certainly faster, smaller, or bigger, with any options you like. Integrated 3G connectivity, card slots for cameras, any connector you want (not like the 2 underpowered USB ports on most macbooks)...

It's sad. I've been waiting for this event but now I don't know what I will buy next month. For the first time in years.

Good luck switching to a PC... A new world of worries and magic crap awaits you.

 

[RPX353]

Apple's Pansy Engineers!

All right you PANSIES! Quit your "log-out" whining and listen up. I'm tired of hearing about "I have to log-out" issue about the graphic processors. I think you ALL have it WRONG anyways! Let me elaborate.... Who the heck runs their graphic sessions in "battery conservation mode"!? I DONT! I don't know about you, but when I start my intense graphic sessions, I'm jacked into the wall. WOW on battery power? Call of Duty on battery? 3GB Photoshop rendering on battery? NO!- I use AC POWER!!! Anyone with any experience knows, you plug-in to the wall to do serious work. Your battery doesn't last but 20mins anyways, so who are they kidding? Apple has taken this whole "conservation" thing a little too far now, and now is robbing us of a possible "SLI" configuration because of their sissy engineers. Allow me....

Apple needs to empower its laptop users with some real power options. When I feel like being a pansy, I use my integrated graphics chip in battery conservation mode. BUT, when I feel like getting down and dirty, let me plug in, REBOOT, and pull as much power from the wall as possible! HOO-RAHHH! Now I'm running blazing fast with BOTH processors enabled simultaneously. Now doesn't that make more sense, and it's APPLE SMART!

STEVE, quit your sissying around and get some engineers with some real balls in there. -RPX353

 

[NRoach]

so much misinformation and speculation ...

It is unlikely that the current implementation of Nvidia's dual-GPU setup on the Macbook Pro will ever support concurrent use of both GPUs. Here's why:

Nvidia's "Hybrid SLI" is really two technologies:

1) HybridPower
HybridPower unleashes graphics performance when needed and switches to quiet, low-power quiet operation for everyday computing. Dial up performance for demanding 3D games and applications; downshift to the mGPU to reduce noise and extended battery life for everyday computing tasks like browsing the Web, word processing, or watching High Definition videos.

2) GeForce Boost
GeForce Boost turbocharges the performance of NVIDIA discrete GPUs when combined with NVIDIA motherboard GPUs. Plug any NVIDIA Hybrid SLI-enabled GPU into any NVIDIA Hybrid SLI-enabled motherboard to enjoy additive performance and more for your money.

The Macbook Pro uses number 1. What this does is switch between the integrated graphics and the discrete GPU when the operating system demands it. Right now, that's only on login/logout. In the future, this could potentially be more flexible.

The reason for this is that the Quartz Compositor (the software that allows GPU accelerated graphics) runs as a child of the loginwindow process. Although it could be uncoupled, right now the compositor is set up when the loginwindow creates an instance for a user at login time. This is pretty low-level functionality and so if that behavior changes, it's most likely to do so in Snow Leopard.

Technology number 2 is GeForce Boost. This is only available when the discrete graphic chip is a 9200, 9300, or 9500 chip. It is NOT available, mac or windows, for the 9600 and higher series. The most likely reason for this the nature of SLI. SLI means Scan Line Interleaving. With 2 GPUs, one GPU draws the odd number rows of pixels and the other draws the even rows. This generally works best when both of your GPUs are about the same speed. Otherwise, the faster GPU is just waiting for the slower one to finish drawing. This is why only the slower discrete GPUs are supported for GeForce Boost. It's because the 9200 series is in the same speed range as the on-board 9400.

It's likely that the discrete GPU in the MacBook Pro is faster on its own than a 9200 would be interleaved with the 9400. Essentially, GeForce Boost uses the following formula:

[Slowest GPU] x2 = peak performance

If the discrete GPU is 2x the speed of the slowest GPU (9400 integrated) then you get no gains from GeForce Boost. It's possible that you could do SLI in a [3 to 2] or [2 to 1] ratio but I'm not aware of any SLI systems on any platform that currently are capable of apportioning SLI rendering based on relative GPU speed. It always requires a matched or near-matched GPU pair.

Finally, you get a benefit from using just the discrete GPU by itself and turning off the 9400. Because the 9400 uses main memory instead of dedicated DDR, when it's active you have the GPU traffic going over the main memory bus. When you disable the 9400 in favor of the separate GPU, you free up some memory bandwidth (even if the RAM's still allocated to the GPU the bus traffic isn't active) and thus the CPU has more resources available. In a gaming or rendering situation, this is probably preferable to a GeForce Boost scenario if you main GPU is fast enough.

Another thing to consider is that Apple is way behind the Windows market in implementing GPU features. For instance, on my MacBook Pro, my CPU load is much higher playing an H.264 video in OSX than it is in Windows. Why? Most modern GPUs offer hardware acceleration of video playback. OSX Leopard currently does not use this functionality to its full extent and still renders the movie in software (but does do window display and compositing in hardware).

Hopefully this helps explain the MBP GPU setup a bit more.