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Is there still a performance warning when using scaled resolutions?

MBHockey

macrumors 68040
Original poster
Oct 4, 2003
3,958
197
New York
Hey all,

Not a developer, but i'm curious if there is still the message that is present in Yosemite about performance decreases when using scaled resolutions.

See the attached picture. This is from a 2015 15" rMBP on Yosemite. It's definitely true -- the iris pro struggles with normal system animations at scaled resolutions. The dGPU does not, but it'd be great to know if these were working better with iGPUs in Capitan.
 

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swestu

macrumors newbie
Jun 11, 2015
3
0
Yes, it's still there. I'm running El Capitan on a Mid 2014 13" rMBP with (only) the Intel Iris.
Screen Shot 306.png
 
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neutrak

macrumors newbie
Oct 16, 2014
24
5
This really isn't the miracle update that people will have you believe. Yes it's a lot better but highest scaled resolution will still affect performance.
 
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MBHockey

macrumors 68040
Original poster
Oct 4, 2003
3,958
197
New York
This really isn't the miracle update that people will have you believe. Yes it's a lot better but highest scaled resolution will still affect performance.

Are you running the beta? Can you comment on performance at scaled resolutions?
 
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Traverse

Contributor
Mar 11, 2013
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There will always be a performance hit because the system has to do much more calculating.

2880/1440 = 2
2880/1680 = 1.714285714
2880/1920 = 1.5

There is a lot more calculating and estimation overhead that will affect performance. Software can make this more efficient, but ultimately more powerful hardware will make it so that the overhead difference is negligible. My 2013 15" rMBP has always ran better at 1920 than 1680 presumably because it is a cleaner calculation ratio.
 
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kwokaaron

macrumors 6502a
Sep 20, 2013
540
172
London, UK
There will always be a performance hit because the system has to do much more calculating.

2880/1440 = 2
2880/1680 = 1.714285714
2880/1920 = 1.5

There is a lot more calculating and estimation overhead that will affect performance. Software can make this more efficient, but ultimately more powerful hardware will make it so that the overhead difference is negligible. My 2013 15" rMBP has always ran better at 1920 than 1680 presumably because it is a cleaner calculation ratio.
Huh... never really thought about why 1920 would perform better than 1680. Still though, like everyone has said, just because it may run more optimally/better doesn't change the fact that procedure-wise it still isn't as efficient as the "Default" resolution. In addition to a performance hit your battery life might also be impacted, which is why I kept it on the default resolution.
 
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bobbie424242

macrumors regular
May 16, 2015
226
258
I'm also curious in scaled performance with the 2014 15" rMBP with integrated graphics. In Yosemite, the Iris Pro really struggle in scaled modes (the ones where performance warning is displayed in Settings), while it is perfectly fine unscaled.
 
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MBHockey

macrumors 68040
Original poster
Oct 4, 2003
3,958
197
New York
Huh... never really thought about why 1920 would perform better than 1680. Still though, like everyone has said, just because it may run more optimally/better doesn't change the fact that procedure-wise it still isn't as efficient as the "Default" resolution. In addition to a performance hit your battery life might also be impacted, which is why I kept it on the default resolution.

Interesting. 1680 seems to run better on my 15" rMBP (2015, AMD gpu) than 1920. maybe i'm just seeing things.
 
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kwokaaron

macrumors 6502a
Sep 20, 2013
540
172
London, UK
From swestu's screenshot I see there's a new "Ambient light compensation" option. Does anyone know what that does?
 
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bobbie424242

macrumors regular
May 16, 2015
226
258
Can someone report if performance is increased using the Iris Pro of a rMBP, using scaled resolution on an external 4K monitor, at resolutions not an integer multiple of the monitor native resolution (eg 1296p or 1440p @ HiDpi) ? On Yosemite, such resolutions are noticeably more jerky (scrolling, animations, ...) than either 1080p HiDpi or 2160p (on a Dell P2415Q monitor whose native resolution is 3840x2160), the latter one being of course unusuable (unreadable text)
 
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xmichaelp

macrumors 68000
Jul 10, 2012
1,815
626
There will always be a performance hit because the system has to do much more calculating.

2880/1440 = 2
2880/1680 = 1.714285714
2880/1920 = 1.5

There is a lot more calculating and estimation overhead that will affect performance. Software can make this more efficient, but ultimately more powerful hardware will make it so that the overhead difference is negligible. My 2013 15" rMBP has always ran better at 1920 than 1680 presumably because it is a cleaner calculation ratio.

That's not how it works... The high you go in scaled resolution the more pixels you're pushing.

At 1920x1200 you're pushing 3840x2400, at 1440x900 you're only pushing 2880x1440
 
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kwokaaron

macrumors 6502a
Sep 20, 2013
540
172
London, UK
That's not how it works... The high you go in scaled resolution the more pixels you're pushing.

At 1920x1200 you're pushing 3840x2400, at 1440x900 you're only pushing 2880x1440
You're right actually. Totally forgot about this. However, if apps aren't updated (which most are), I think they're simply "pixel-doubled", which should use these scaling factors.
 
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Traverse

Contributor
Mar 11, 2013
6,992
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Here
That's not how it works... The high you go in scaled resolution the more pixels you're pushing.

At 1920x1200 you're pushing 3840x2400, at 1440x900 you're only pushing 2880x1440

It may just be a miscommunication of words, but the graphics chip only has to "push" 2880x1800 pixels. The system renders them at 3840x2400 and then down samples to 1920x1200 which isn't a clean downsample so there is some loss of quality and more stress on the GPU.
 
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swestu

macrumors newbie
Jun 11, 2015
3
0
From swestu's screenshot I see there's a new "Ambient light compensation" option. Does anyone know what that does?

I've read it's supposed to do the same as f.lux, but I haven't seen it doing stuff yet. ^^
 
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