[Samsung Galaxy A20 ROMs, Kernels, Recoveries, & Ot] jajk:
There are so many questions asked over and over again about how to configure the kernel for a desired outcome..... max performance, best battery holdup, fix freezing etc.

I will post this for those who did not attend school just for the bus ride or playtime. All dumb questions ignored so if I don't respond, you asked a dumb question or made a dumb comment.

We have a choice of 1 custom kernel (Eureka) that can be comprehensively tweaked thanks to many of the settings being moved into the DTB partition. Currently, there are 20 versions of the DTB image that can be selected on kernel installation - 10 enforcing and 10 permissive with 10 different mixes of cpu and gpu frequencies to suit most needs. The default sets everything to maximum and is the cause of the majority of freezing / crashing on an A205 phone that has a lower quality SoC than the other A series compatible phones. Most will end up using DTB2 to fix instability but even this might not be enough. You then have to consider a lower frequency DTB which lessens the attractiveness of using this custom kernel. Why not make your own flavor of DTB that can more accurately reflect what you can run on your specific SoC? Here's how:

Open up the Eureka Kenel zip file in whatever zip extractor you use.

Extract DTB2.img from the zip file (either permissive or enforcing version depending on what your chosen ROM needs)

Now open DTB2.img using a hex editor

Now look at the following which is a list of addresses (in hex), what the value at this address is defining and a list of possible settings. Frequencies are in MHz and the hex code to set it is the frequency in kHz example: 343MHz is 343000kHz, 053BD8 is hex for 343000.

GPU:

5CA5 GPU max freq

5CB5 GPU boost freq

5CC7 GPU boost %load

Possible freqs (MHz):

343 053BD8

450 06DDD0

545 0850E8

676 0A50A0

845 0CE4C8

1001 0F4628

1100 10C8E0

1200 124F80

1300 13D620

CPU smalls:

71B1 CPU min freq

71C1 CPU min freq

71D1 CPU max freq

71E1 CPU max freq

71F1 CPU boost freq

Possible freqs (MHz):

208 032C80

343 053BD8

449 06D9E8

546 0854D0

676 0A50A0

757 0B8D08

839 0CCD58

902 0DC370

1014 0F78F0

1144 1174C0

1248 130B00

1352 14A140

1482 169D10

1586 183350

1690 19C990

1794 1B5030

CPU bigs:

73B9 CPU min freq

73C9 CPU min freq

73D9 CPU max freq

73E9 CPU max freq

73F9 CPU boost freq

Possible freqs (MHz):

208 032C80

312 04C2C0

520 07EF40

728 0B1BC0

936 0E4840

1144 1174C0

1352 14A140

1560 17CDC0

1664 196400

1768 1AFA40

1872 1C9080

1976 1E26C0

2080 1FBD00

2184 215340

2288 22E980

First thing: The default min freq of 208MHz does not save any more battery than setting this to 343MHz (for small cpus) and 312MHz for bigs.

Next thing: The A205 more than likely will become unstable at anything above 2080MHz for the big cpus but can probably cope with 1794MHz on the small cpus. Each SoC is slightly different so you must test what your phone can handle, not what someone else's phone can do!

Next: It is highly unlikely that your A205 will be stable with the GPU maxxing out at 1300MHz. You will not be aware of this until the gpu governor actually cranks the gpu up to that frequency i.e. you can remain oblivious to it for some time and incorrectly assume something else is causing freezes / crashes / glitching.

Next: There are many more settings in the DTB relating to boost frequencies on various input conditions i.e. screen touches, keyboard clicks, mouse clicks etc. Most of these are set to peak at 1144MHz which seems quite reasonable so I have not sought to specifically identify and edit these.

Edit: So here are the input boost frequencies: (address, name, function, freqs)

I assume the first addresses in each block are for BIGS and the 2nd lot are for SMALLS. It seems to work well to set all the BIG freqs to 936 and all the SMALLS to 839 since there is an abundance of upward boosting from other sources such as the Governor and Exynos specific drivers.

50B1 key1 IKEY 1144

5181 key2 ITOUCHKEY 1144

5255 5259 525D 5285 5289 528D key3 ITOUCH 1144 1144 936 839 839 839

5369 536D 5391 5395key4 IMULTITOUCH 1144 936 839 839

545D 5461 5485 5489 key5 IKEYBOARD 1144 936 839 839

554D 5551 5575 5579 key6 IMOUSE 1144 936 839 839

5641 5669 key7 IMOUSE WHEEL 1144 839

5735 5739 575D 5761 key8 IPEN HOVER 1144 936 839 839

5821 5825 5849 584D key9 IPEN 1560 936 839 839

58E5 key10 IKEY_TWO 1872

Recommendations:

Min Freqs:

Set GPU to 343MHz, small CPUs to 343MHz and big CPUs to 312MHz. This is the maximum power saving you will get and offer minimal lag as the frequencies scale up to meet demand.

Set the GPU max freq to 845MHz while you are establishing what is stable for the CPUs.

Set GPU boost to 545 or 676MHz (depending on your compromise between battery and performance)

Set GPU boost load trigger level from the stock 75% down to 50~60%. Again depending on your compromise between battery and performance. Lowering this setting has a significant impact on reducing perceived lag so the stock setting was probably far to high.

Set big CPU max freq down to 2080MHz. This solves most crashing that is due to the cpu being overclocked too far.

Set small CPU max freq to 1794MHz unless your SoC proves to be unstable at this.

Set the CPU boost freqs to something quite low (around 700~900MHz). There are other boosts that override this basic CPU boost freq so you will almost never see it.

Note: If you want maximum battery savings, setting the max freqs lower seems like a logical thing to do but it is not! If you halve the cpu freqs, you double the amount of time they must remain on but you do not halve the power consumption so you end up consuming more power....

Make the changes and save the DTB.img file and flash it in recovery to DTB partition and reboot.

Install hKtweaks_v2.2.2 or your favorite kernel tweaker that can deal with Exynos SoCs (not many can)

Take a look at the cpu and gpu settings to confirm that your edited DTB file is producing the expected results i.e. min and max freqs agree with what you set.

You are done!

Err..... only kidding there is more to do.

Now back to the issue of the GPU max freq. In hKtweaks you can override the settings inherited from the DTB (within the limits set by the DTB). The max GPU freq is also associated with a core voltage. Lowering the voltages will make the GPU run cooler (use less power) but also it will not overclock as far as if the voltage is higher. Here is the dangerous bit - you can increase the voltage to make it overclock higher but cause it to overheat quicker which will make it throttle back to a lower freq. There is also an error in the DTB: Look at the settings for throttling the frequency back at certain temps. Set GPU LEVEL 3 Throttling Freq to 343MHz to fix the error.

Have a play with the GPU settings in hKtweaks without setting Apply on boot so if you set something that crashes the phone, it will revert to normal on a reboot. When you are positive you have the best GPU settings. then set Apply on boot.

Now you are done!

Err..... not quite, there is more.