Discussion Terrible cpu schedule for a14

amosliu137

Junior Member
Jul 12, 2020
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I acknowledge that A14 is very fast. However, in the real application which really need performance such as high demanding game, A14 is terrible. Usually in just 1-2 minutes of game, the FPS will suddenly decrease below 10.
What I observed is performance cpu core will close for 20 seconds when iPhone is in the fair thermal state. Moreover, I used the third app to measure the efficient core at just 600 MHz. In this case, it is totally unplayable.
You can find the similar results for benchmark, in 3dmark sling shot, it is below 10fps at 1:20. When you run Aztec high offscreen test after onscreen in gfx, the frametimes is over 250 ms in the middle.
The ridiculous point is behavior of cpu is normal when the thermal state is serious.
 

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amrnuke

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Apr 24, 2019
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This is a culmination of two of the problems I've noticed before:

1) My iPhone 11 Pro gets really hot, really easily in a relatively slim plastic case.
2) Apple have increased power consumption 30-40% for a 15-20% gain in speed.

While I can't help but wonder if your issue is specific to your device or hardware/software setup, I know for certain that Apple are pushing the envelope and at some point, it has to bend. This might be the point in time it does.

Certainly, if this is the type of behavior you get at this level of IPC + clocks, it makes Nuvia's claims all that much more unbelievable.
 

coercitiv

Diamond Member
Jan 24, 2014
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Apple are targeting "bursty" phone workloads. Nuvia are targeting servers. Their power management policies are going to look very different.
Normally I would agree, yet Nuvia insisted on comparing their product to Apple and Qualcomm cores too.
 

IntelUser2000

Elite Member
Oct 14, 2003
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Normally I would agree, yet Nuvia insisted on comparing their product to Apple and Qualcomm cores too.

They are also comparing to cores that will be 18 months old by that time, if not full 2 years.

For example, Tigerlake's curve is going to look similar to the A12X curves. A14 gets nearly 1600 points, so that gets threateningly close to Nuvia's numbers. Just a 10% improvement then they'll be on the low end of Nuvia's claims. Even Alderlake is going to get close if it improves another 20%.

It's competition is not going to be A13 and Icelake as they claimed but A15, Alder Lake, and Zen 4.
1603883640438.png


Many new, nice sounding technologies have failed because the boring, existing technologies have improved to the point that there was no market for the new tech anymore.
 
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DrMrLordX

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Apr 27, 2000
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I've heard of iPhone users complaining that mere video conferencing applications can make their phones overheat and crash. Not surprised that a game could do the same. A14 should be much more impressive in different form factors with better cooling and different power policies.
 
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coercitiv

Diamond Member
Jan 24, 2014
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They are also comparing to cores that will be 18 months old by that time, if not full 2 years.

Many new, nice sounding technologies have failed because the boring, existing technologies have improved to the point that there was no market for the new tech anymore.
They acknowledge this at the end:
We realize the companies we have measured against in these tests are not standing still and will have new products in the market over the next 18 months. That said, we believe that even with significant performance gains (20%+) with new CPU architectures, we will continue to hold a clear position of leadership in performance-per-watt.
That being said, I do agree with you: they seem optimistic about their ability to execute and pessimistic about the competition.
 
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amrnuke

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Apr 24, 2019
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I've heard of iPhone users complaining that mere video conferencing applications can make their phones overheat and crash. Not surprised that a game could do the same. A14 should be much more impressive in different form factors with better cooling and different power policies.
A13 overheats and battery life drops massively with any type of zoom, doxy.me, web meeting, etc. I haven't had it crash yet but it's annoying running around on 25% battery life because you just had a 45 minute meeting.
 

Hitman928

Diamond Member
Apr 15, 2012
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They acknowledge this at the end:

That being said, I do agree with you: they seem optimistic about their ability to execute and pessimistic about the competition.

The possibly even bigger variable is when Nuvia will actually have silicon ready to sell. That 18 month comment was taken by Ryan to mean they'll have silicon ready in about 18 months from their presentation but then Nuvia contacted Ryan and told him that he misinterpreted that statement. So, if it turns out to be longer than 18 months, you may not be looking at Nuvia going up against the next gen competition, but they may have to go up against the generation after that.
 

coercitiv

Diamond Member
Jan 24, 2014
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So, if it turns out to be longer than 18 months, you may not be looking at Nuvia going up against the next gen competition, but they may have to go up against the generation after that.
Yup, even with the somewhat underwhelming results Apple has with A14 (relative to their own "gold" standard and assuming these early reports of burst power usage are true), there's still a very good chance Apple will offer similar results in 12 months, let alone in 18-24.
 

amosliu137

Junior Member
Jul 12, 2020
22
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61
This is very common in iPhone 12.
This is a culmination of two of the problems I've noticed before:

1) My iPhone 11 Pro gets really hot, really easily in a relatively slim plastic case.
2) Apple have increased power consumption 30-40% for a 15-20% gain in speed.

While I can't help but wonder if your issue is specific to your device or hardware/software setup, I know for certain that Apple are pushing the envelope and at some point, it has to bend. This might be the point in time it does.

Certainly, if this is the type of behavior you get at this level of IPC + clocks, it makes Nuvia's claims all that much more unbelievable.
in that case, it is just 4 efficient core at 600mhz.
 

amrnuke

Golden Member
Apr 24, 2019
1,181
1,772
136
Yup, even with the somewhat underwhelming results Apple has with A14 (relative to their own "gold" standard and assuming these early reports of burst power usage are true), there's still a very good chance Apple will offer similar results in 12 months, let alone in 18-24.
That's a fair point. Their leveraging of TSMC's node advances, small die size (88 mm2) helping cost and yields, and clock speed ramping almost assures we'll see 15-20% improvements as long as TSMC continues to work it hard. The only issue will remain heat and at some point they'll need to ramp down clocks and re-engineer the core more heavily to ameliorate heat density and heat dissipation issues. I can't imagine the heat/thermal throttling issues caused by packing 20% more transistors than A14 on the same size die and ramping up to 3.1 GHz... might not be a huge issue since the whole phone is a heatsink... but people throw thermal insulation over the top of it. I wonder if the day is coming when we'll see people buying aluminum-embedded cases with thermal paste over the part of the phone with the CPU lol...
 

name99

Senior member
Sep 11, 2010
404
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I acknowledge that A14 is very fast. However, in the real application which really need performance such as high demanding game, A14 is terrible. Usually in just 1-2 minutes of game, the FPS will suddenly decrease below 10.
What I observed is performance cpu core will close for 20 seconds when iPhone is in the fair thermal state. Moreover, I used the third app to measure the efficient core at just 600 MHz. In this case, it is totally unplayable.
You can find the similar results for benchmark, in 3dmark sling shot, it is below 10fps at 1:20. When you run Aztec high offscreen test after onscreen in gfx, the frametimes is over 250 ms in the middle.
The ridiculous point is behavior of cpu is normal when the thermal state is serious.

This seems like a scheduler/power management bug more than a hardware fault.
What I mean is that any sort of optimal design will not fall off a cliff like that, will it? Surely as you start to see you're approaching a problem you'll throttle gradually, not all at once.

Do you see more sensible behavior on say A13 or A12?
 

amosliu137

Junior Member
Jul 12, 2020
22
38
61
This seems like a scheduler/power management bug more than a hardware fault.
What I mean is that any sort of optimal design will not fall off a cliff like that, will it? Surely as you start to see you're approaching a problem you'll throttle gradually, not all at once.

Do you see more sensible behavior on say A13 or A12?
you are right. A12 or A13 behave normal.
 
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