Hi,

I've just installed BOINC on my Samsung S10 smartphone (the Exynos version) and added the Seti@Home project. Everything works well except that I noticed that only 4 of the 8 CPU cores are used.

Here's the specs of this smartphone:
Octa-core (2x 2.73 GHz Mongoose M4 / 2x 2.31 GHz Cortex-A75 / 4x 1.95 GHz Cortex-A55) - EMEA/LATAM

The hardware monitoring app I have (CPU-Z) shows that only the cores that go up to 1.95 Ghz are used (cores 0,1,2,3) which looking at the specs above should mean that only the Cortex-A55 cores are getting used. Why would that be and is this normal? I've set BOINC to use all 8 cores in the settings.

Thanks in advance!

Most modern smart phones use ARM big.LITTLE cores where the low power slow cores (Little) can be used by apps etc. and the high power fast cores (Big) can be used by Android only. That's done because these fast cores are so power hungry and generate a lot of heat.

So when you set BOINC to run 8 cores, it'll double load each Little core with 2 tasks, actually slowing down calculations. BOINC isn't capable of using the faster cores, although the developers are looking into it to see if they can use them in the future.

For the moment, it's best to set BOINC to use just 4 cores. It'll then load the 4 Little cores. Also wise to use some form of cooling on the device, as running 24/7 will cause the battery to bloat when it's exposed to this increased heat all the time.

I'm running BOINC/Seti on 4 devices, three of which lie in the path of 140mm fans spinning at 5V (half speed) to help aid keeping them cool. Works well.

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Thanks a lot for the in-depth explanation, Jord! I guess I'll put it back to 4 cores as per your recommendation then.

BTW, while running BOINC, I have my phone sitting on top of my PC case which has 3 large fans. These do a pretty good job at cooling the phone by blowing cold air at it. :) The back of the phone actually feels like a cold metal surface to the touch. According to HWmonitor Pro, my battery is currently 17.9*C after 3-4 hours of Seti. Probably the glass back on the S10 helps too. After all, glass is a much better heat conductor than plastic.