Confused about virtulization and GPU usage.

MaxBurn

macrumors 65816
Original poster
Nov 25, 2010
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So as described in other threads when running bootcamp you are forced to use the discrete GPU, that's a bit of a down side on battery life I want to try and minimize. I need some gaming but I am trying to figure out if there is a way to better battery life for work related activities in windows.

Three questions:

1. Work activities would be some light/moderate SQL usage with a proprietary tomcat based application and IE work. Do you think this type of thing virtualized just wipes out any savings I would get by turning off the discrete GPU?

2. When using vmware or parallels can I point it to the bootcamp partition and force it to use the intel integrated graphics in an attempt to save power? (I'm thinking this is a NO)

3. Or does it make a difference if the whole windows os is installed in vmware or parallels? I wouldn't be completely opposed to have one for gaming and one for work power saving but only if it makes a real difference.


The machine in question would be a late low end 2011 15" with the quad i7 and 6750M.
 

dusk007

macrumors 68040
Dec 5, 2009
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What keeps you from using gfxCardStatus and simply force the Intel GPU.
Usually there are troubles when you switch the GPU while the VM is running. It doesn't outright crash but it is a lot slower than it should be in my experience.
The only thing one can do is restart the VM and be glad is doesn't take that long with a SSD.

force the Intel always unless you mean to play a game or plug in an external screen.

I am not sure I really understand your questions. In any case you can only force the native OS (OSX) to use whatever GPU you want by means of gfxCardStatus. VMWare Parallels don't give a **** what GPU is running. Apple's drivers suck though and thus a restart of the VM after a switch is usually necessary for full performance at least in my experience. It also doesn't matter if the VM that is running is the bootcamp partition, some Windows Image, Linux, Solaris or whatever.
 

MaxBurn

macrumors 65816
Original poster
Nov 25, 2010
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What keeps you from using gfxCardStatus and simply force the Intel GPU.
I wasn't sure that this would apply to the VM, especially when pointing to a bootcamp partition that only can use the discrete GPU.

If it does that's cool, I will give that a try.
 

snaky69

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Mar 14, 2008
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I wasn't sure that this would apply to the VM, especially when pointing to a bootcamp partition that only can use the discrete GPU.

If it does that's cool, I will give that a try.
The boot camp partition gets virtualized, just like any regular old virtualizing, so no, the discrete GPU isn't being used like booting into bootcamp would, they are two very different things.
 

MaxBurn

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Nov 25, 2010
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Thanks, that really sounds like the best of both worlds then.
 

snaky69

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Mar 14, 2008
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Thanks, that really sounds like the best of both worlds then.
You'll see an impact on battery life still, virtualizing is RAM hungry and can be CPU hungry at times. You'd have to compare for yourself, but both methods will have a big effect on your battery life.
 

MaxBurn

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Original poster
Nov 25, 2010
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You'll see an impact on battery life still, virtualizing is RAM hungry and can be CPU hungry at times. You'd have to compare for yourself, but both methods will have a big effect on your battery life.
I get this but I am hoping that if I can lock the 6750M off I will still be ahead in power savings verses bootcamp and being forced to have the 6750M running all the time. Maybe it will be a small savings or none at all, will see.

Would be ideal if we could switch the 6750M off in bootcamp, even if it required a reboot to switch it, oh well.
 

dusk007

macrumors 68040
Dec 5, 2009
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Depends on the workload. The overhead of virtualization can eat up all the savings from the Intel GPU quite quickly by causing higher CPU load.
 

XandeR803

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Jul 25, 2008
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The boot camp partition gets virtualized, just like any regular old virtualizing, so no, the discrete GPU isn't being used like booting into bootcamp would, they are two very different things.
I'm not sure how vmware fusions works but for parallels there is an option to use either the integrated graphics or discrete graphics. I use excel 2010 in parallels off my bootcamp partition a lot and the battery life is not too much of a hit (can still get 4-5 hours of work). This is in an early 2011 2.3.
 

snaky69

macrumors 603
Mar 14, 2008
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I'm not sure how vmware fusions works but for parallels there is an option to use either the integrated graphics or discrete graphics. I use excel 2010 in parallels off my bootcamp partition a lot and the battery life is not too much of a hit (can still get 4-5 hours of work). This is in an early 2011 2.3.
I don't own a MBP with two graphics cards(yet), so I can't really say whether or not this works in either program.
 

bill-p

macrumors 68000
Jul 23, 2011
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I get this but I am hoping that if I can lock the 6750M off I will still be ahead in power savings verses bootcamp and being forced to have the 6750M running all the time. Maybe it will be a small savings or none at all, will see.

Would be ideal if we could switch the 6750M off in bootcamp, even if it required a reboot to switch it, oh well.
Or alternatively, I think you can try to undervolt the 6750M while under Windows so that while you don't game, it wouldn't suck as much battery.

As mentioned, the tradeoff of virtualization is that CPU usage is still high enough, so it pretty much cancels out the power saving achieved with just the integrated GPU. If you have low RAM, it'll also grind your HDD non-stop.
 

MaxBurn

macrumors 65816
Original poster
Nov 25, 2010
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I'm not sure how vmware fusions works but for parallels there is an option to use either the integrated graphics or discrete graphics. I use excel 2010 in parallels off my bootcamp partition a lot and the battery life is not too much of a hit (can still get 4-5 hours of work). This is in an early 2011 2.3.
Thanks, 4-5 hours is no problem at all. The anandtech review with their bootcamp battery time is what I was worried about. Looking at the chart and seeing it cut down by half is very concerning but I guess they are reporting that much as well.

Or alternatively, I think you can try to undervolt the 6750M while under Windows so that while you don't game, it wouldn't suck as much battery.

As mentioned, the tradeoff of virtualization is that CPU usage is still high enough, so it pretty much cancels out the power saving achieved with just the integrated GPU. If you have low RAM, it'll also grind your HDD non-stop.
As an overclocker in the PC world for many years I can just say I have had enough with the whole situation and I don't want to deal with it. Just interested in running things in spec.

On the other side of your comment I will be starting out with 4gb but quickly upgrading to 8gb and a SSD for the lion/bootcamp volumes.
 
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