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Comparing the A14 Bionic to a 15-inch MacBook Pro's 6 core CPU is meaningless, and here's why

Started by Redaktion, January 18, 2020, 16:30:08

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S.Yu

Quote from: Helium007 on January 20, 2020, 22:52:10
Quote from: S.Yu on January 20, 2020, 17:26:36
Quote from: Solandri on January 19, 2020, 21:20:54
With the 3000 mAh battery found in typical phones, @ 3.7 Volts, a power draw of 2 Watts would completely deplete it in 5.5 hours.  5 Watts would deplete it in 2.2 hours.  8 Watts would deplete it in 1.4 hours.  So I'd say the 2 Watt figure is pretty accurate.
No, instead it would make the 5W figure fairly accurate, for example Mate30P, NBC's numbers, 4500mAh, 3.65hrs load, that's about a sustained load of 4.56W. Only sustained load measures the heat dissipation between room temperature and the temperature allowed for the SoC.

Well how do they measure that? Thats not SoC LOAD but total POWER input I guess. This is probably total power input and even if it would be total power dissipation (which you cannot measure easily), it would be dissipation of ALL components.  For example RAM and PMIC chips are dissipating quite big amount of power. Only way how to get some sort of approximate SoC dissipation values could be cutting all SoC power lines and connecting them to bench supply...

So I am still standing with walues about 2 or 2,5W peak.

Sorry but my job is embedded electronics design and manufacturing, so I really would like to hear some reasonable infomation about this
"Typical smartphone can dissipate about 2 Watts of energy" is what you said, so I naturally assumed a total, only assuming that the SoC alone would be the component with the largest increase in power draw under load and if something notably throttles under load it would be the SoC itself.
If what you meant was actually "Typical smartphone can dissipate about 2 Watts of energy from the SoC only" then I don't have much against that, but Anandtech regularly gives power numbers that should be from the SoC alone(a read of power figures from the chip itself, for what it's worth), and those regularly surpass 3W on Spec2006 workloads, and on page 8 of the comments you'd see that the author noted that the Apples ran at near peak clock speeds for the duration of the test.
https://www.anandtech.com/show/15207/the-snapdragon-865-performance-preview-setting-the-stage-for-flagship-android-2020/2

Helium007

OK, my bad for forgetting "2 W from the SoC only" word.

It still doesnt make a big change of my point there. This actually can reach for 3W peak (for some time) in good thermal scenarios, like usual 25C ambient temperature and phone cooled to this temp.

Anyway if you look to Anandtech comparisons, you can still see that there is 20 up to 50% power gap in benchmark in peak/sustained load. So his is actually supporting my talks that phone "thermal solution" is really not designed for sustained load and is very under-dimensioned because of design and price. In laptops you will never see such drastical performance change.

And final thing - I have at work devkit with NXP IMX8 4x1,5 GHz 28nm SoC that can disspate 4W (here I can tell exact number beceause datasheet is not under NDA and states this). I applied custom heatsink about 15x15cm with fan guess what? I always get consistent benchmark numbers, no matter how long I run it. This wasnt same with factory heatsink it came with.

One thing that would be interesting to see thermal limits on these SoCs, because almost all have datasheets under NDA. I wonder how they set up thermal die limits. Because no one cares about long live of phone, they could set it very high to bump absolute raw power...

S.Yu

Quote from: Helium007 on January 21, 2020, 19:15:05
OK, my bad for forgetting "2 W from the SoC only" word.

It still doesnt make a big change of my point there. This actually can reach for 3W peak (for some time) in good thermal scenarios, like usual 25C ambient temperature and phone cooled to this temp.

Anyway if you look to Anandtech comparisons, you can still see that there is 20 up to 50% power gap in benchmark in peak/sustained load. So his is actually supporting my talks that phone "thermal solution" is really not designed for sustained load and is very under-dimensioned because of design and price. In laptops you will never see such drastical performance change.

And final thing - I have at work devkit with NXP IMX8 4x1,5 GHz 28nm SoC that can disspate 4W (here I can tell exact number beceause datasheet is not under NDA and states this). I applied custom heatsink about 15x15cm with fan guess what? I always get consistent benchmark numbers, no matter how long I run it. This wasnt same with factory heatsink it came with.

One thing that would be interesting to see thermal limits on these SoCs, because almost all have datasheets under NDA. I wonder how they set up thermal die limits. Because no one cares about long live of phone, they could set it very high to bump absolute raw power...
Within the scope of running Spec, IIRC that test lasts for over an hour, so the figures quoted is close to stable numbers of a sustained load, there were efficiency numbers derived after all, and in another article there was a hot/cold comparison of efficiency, hot is the default numbers quoted at Anandtech and cold is the peak achievable before throttling, A13's cold was...I think >7W, hot is what you read from the link.

Reza

A reason for Comparing arm vs x86 is that Apple M1 x86 Performance is Really More Efficient than Regular x86 CPUs (in the same Class)
Key to Success in Computing World is More Efficient Transistors against More Wats and Cores

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