[Sony Xperia XZ2 Guides, News, & Discussion] Haldi4803:
Powerdrain & Thermal Throttling

Okay... here we go... Wallcharger + Snapdragon Profiler...

First i've charged my phone fully to check Idle drain. Around 0.3W check.

About GPU testing:

You see the Idle 1.2W Powerdrain at the beginning? That's because Snapdragon Profiler is connected via ADB over WiFi. Quite a lot compared to the 0.3W Idle...

The first few Peaks until 12 Minutes are a failure because i've accidently started the sublevel Benchmarks^^

The first real Peak to 5.4W is a CarChase OnScreen.

The 1.7G on Clocks/Second is a reading error, normal Max is 710Mhz.

You can see the Temperature reaching 66°C and throttling starts, GPU going to 600Mhz, also Big Cores limiting to 2.17ghz.

The 2nd Peak is CarChase OffScreen.

You can see the big cores dropping in Frequency pretty early. GPU maxed out at 710mhz, until the phone reaches 68°C. GPU throttles heavily, and Big cores are going Offline putting the Load on small cores.

Which caused a drop in Powerusage from 5W to 3.7W

The last Peak is Manhatten OffScreen.

When Throttling starts at 68°C GPU drops from 710mhz to 600mhz and task migration from big to small cores.

The Powerdrain is reduced from 4.4W to 3.9W

About CPU testing:

Well.... that didn't work as well as expected... In the Powermonitor graph you can see i've used CPU Load Generator started with 1 Thread, and added 1 more after 1 Minute, until i had 4 threads.

Admittely the phone was already 45°C when i started this test... therefore i've already had throttling before i even started.... But well.... i've expected more...

The same peaks that are visible in the Powermonitor graph are also clearly visible in the temperature graph on Snapdragon Profiler.

So even if the phone is throttling, it allows Burstpower/increased thermal limit for new tasks, to reduce lag. Pretty neat.

Edit: Here we go... on a cold device:

As always, until Minute 1.2 is pure IDLE, from 2-2.7 is whit ADB over WiFi and Snapdragon Profiler connected.

At Minute 3 you see the start of the first Task. Using around 3.3W

At 4.2 you see the 2nd Task starting, generating 4.4W load

At 5.2 the 3rd Task starts, using up to 6.3W but shortly after (timestamp 225s in the graph below) the phone reaches 68°C and starts throttling. Load drops to 5W. because the continous Load of 5W is not sustaineable the phone throttles down to 4.1W (timestamp 245s)

Tt 6.2 Minutes the 4th Task is started, which generates 5.2W, this causes the phone to get almost 68°C again (timestamp 275s) and drops powerdrain to 3.3W, the phone cools down to about 60°C (timestamp 295s) and stop throttling, therefore peaking to 6.1W and rising to 68°C again in 10 seconds. Trying to limit powerdrain to 5.2W for the next 5 seconds fails, and task migration kicks in turning core7 offline and pushing load onto little cores. Limiting Big cores to 2.4ghz and using 3.9W

(timestamp 0s equals 2 Minutes on the other graph)

Edit2:

So what does that mean for Performance?

I've used the App CPU Throttling Test to create a workload and also Display it's performance. Here you can see 3 threads at work. Full Performance 125.9GIPS

The 2 Minute run does not throttle, Snapdragon Profiler proofs that :)

Using the app with 7 Threads causes throttling twice. But again, all cores are shown at full frequency.

Using Snapdragon Profiler we can see the phone throttling at 64°C (timestamp 447s) and later on at 60°C (timestamp 490s)

The performance drops from 125.9Gips to 104.9Gips. Nothing in Snapdragon profiler would indicate that.... CPU frequency stays the same and Load is also equal.