Android CPU usage by DJi Pilot, Ultimate Flight and Ltchi app comparison...

n6vmo · Aug 22, 2015

I have DJi Pilot V1.2.0, Ultimate Flight V3.21 and Litchi V1.7.6 installed on my Samsung Galaxy Tab 4.

GooglePlay services has always been downgraded in order for the tablet to perform better.

While monitoring the tablet CPU usage with the Cool Tool app and my P3A sitting inside on the bench, I observed the following CPU usage while switching between each app. The P3 remained powered continuously throughout the test. I exited each app and started each app in the order below.
No mission profiles were run, only sitting idle with the camera view.

DJi Pilot - 33 - 45%

Ultimate Flight 90 - 98%

Litchi - 95 - 98%

I would have hoped the developer apps would be equal to or have less CPU usage than DJi's Android apps.
But, twice as much...wow! What are these two developer apps doing to require twice the CPU horsepower?

Sloppy coding just to get something to market?

FredzMaxxUAV · Aug 22, 2015

What Android version and Google play services version?

n6vmo · Aug 22, 2015

Fredz said:
What Android version and Google play services version?

Using Android 4.4.2 and Google Play Services 6.5.99

Trumple · Aug 22, 2015

CPU usage doesn't mean much. Your device is a quad core. It could simply be the case that the DJI app is not utilizing multi-threading as much as it could, and is therefore not utilizing your CPU effectively. The 3rd party apps might then be using multi-threading to maximize usage and make the app run better. Is there less lag in the 3rd party apps? Can you notice a difference in performance?

Also that's quite an old Android version, and if I know Samsung there'll be a lot of bloatware running in the background.

Trumple · Aug 22, 2015

Also consider that the hotter the phone gets, the more it underclocks itself in an attempt to cool down. That is why you see the live feed start to judder before your phone overheats on a hot day. You tested the other two apps last, after the phone had heated up. This effectively "lowers the CPU power available" for the latter tests. Think of it as a sprinter getting tired after the first few sprints then expecting him to sprint some more, then exclaiming that he got slower in the later sprints. A fair test would be to allow the phone to cool between tests.

n6vmo · Aug 22, 2015

Trumple said:
CPU usage doesn't mean much. Your device is a quad core. It could simply be the case that the DJI app is not utilizing multi-threading as much as it could, and is therefore not utilizing your CPU effectively. The 3rd party apps might then be using multi-threading to maximize usage and make the app run better. Is there less lag in the 3rd party apps? Can you notice a difference in performance?

Also that's quite an old Android version, and if I know Samsung there'll be a lot of bloatware running in the background.

Good points. I use 'All in One' app to turn off all unnecessary services and place the tablet in 'Airplane' mode just to squeeze out every bit of performance.

With a temp 64degs inside on the bench, I retested in reverse order, no change in results.

I still notice an increase in lag/stutter using the UF and Litchi. While the DJi Pilot at 40% is noticeably smoother. The video streaming setting is 4Mbps in all three apps and using a clear channel 24.

Trumple · Aug 22, 2015

n6vmo said:
Good points. I use 'All in One' app to turn off all unnecessary services and place the tablet in 'Airplane' mode just to squeeze out every bit of performance.

With a temp 64degs inside on the bench, I retested in reverse order, no change in results.

I still notice an increase in lag/stutter using the UF and Litchi. While the DJi Pilot at 40% is noticeably smoother. The video streaming setting is 4Mbps in all three apps and using a clear channel 24.

If the DJI app is running smoother and with less CPU utilization in that scenario, then you've found a winner

Only thing I can think of is that Litichi is in alpha

n6vmo · Aug 22, 2015

I will be flying Litchi for the first time in about an hour. Got a couple of small Orbit and Waypoint missions I want to try.

bimmy · Aug 22, 2015

My experience is just the way around . on my Samsung Galaxy s6 edge the DJI go app stutters alot and while flying on the second battery it keeps freezing. Litchi never experienced any lag or stutter. And u.f. i did not test it alot so I can not say for 100% yet.

DaGunn · Aug 22, 2015

If you don't kill all apps in memory before running the next app you are handicapping every app that is run after the 1st. Repeat the test multiple times but running apps in different sequences. Then average the results.