[Q] XU4 Mali GPU frequency scaling (DVFS)

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dongkwan
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[Q] XU4 Mali GPU frequency scaling (DVFS)

Unread post by dongkwan » Thu Aug 08, 2019 2:27 pm

[Q] XU4 Mali GPU frequency scaling (DVFS)
Hi.
I'm working on XU4 and N2.
Actually, N2 v4.9 does not give any GPU frequency at /sys/devices/platform/ffe40000.bifrost
Anyway, I can see the frequency with XU4 v4.14 at /sys/devices/platform/11800000.mali/devfreq/devfreq0/cur_freq
In initial, As the GPU governor is performance, the frequency is 6000000000.
Then, after having changed the governor performance to simple_ondemand, the frequency changed 1770000000.
When I execute any program, e.g, OpenCL, or glmark2, the frequency should increase, isn't it?
However, the frequency remained 1770000000. What should I do?

+
I experimented thermal influence to frequency. I increase the temperature above 100'C with the performance GPU governor.
Then, the frequency remained 6000000000, too.
Has XU4 DVFS function? Then what temperature is limit?

joy
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Re: [Q] XU4 Mali GPU frequency scaling (DVFS)

Unread post by joy » Tue Aug 13, 2019 9:33 am

dongkwan wrote:
Thu Aug 08, 2019 2:27 pm
[Q] XU4 Mali GPU frequency scaling (DVFS)
+
I experimented thermal influence to frequency. I increase the temperature above 100'C with the performance GPU governor.
Then, the frequency remained 6000000000, too.
Has XU4 DVFS function? Then what temperature is limit?
XU4 has DVFS function for CPU and GPU, (Exynos5422 has temperature sensors to measure CPU and GPU part.)
and you can check temperature trip points under the node /sys/class/thermal/thermal_zone4 that is assigned to GPU.

But so far I have no idea which part defines and controls its thermal rule and governor logic. :(

dongkwan
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Re: [Q] XU4 Mali GPU frequency scaling (DVFS)

Unread post by dongkwan » Wed Aug 14, 2019 1:21 pm

Actually, At kernel version 3.10, the frequency changed related to the GPU usage with 'Booster' GPU governor.
However, At kernel version 4.9 or 4.14, the frequency fixed at 177000000 with 'Simple_ondemand' GPU governor.

In addition, as the thermal increases above 90'C, the DVFS works with throttle at v3.10
However, at v 4.14, the frequency continuously fixed. As the thermal increases above 105'c, the sensor just show fixed temperature 100'c

joy
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Re: [Q] XU4 Mali GPU frequency scaling (DVFS)

Unread post by joy » Sun Aug 18, 2019 11:16 am

dongkwan wrote:
Wed Aug 14, 2019 1:21 pm
Actually, At kernel version 3.10, the frequency changed related to the GPU usage with 'Booster' GPU governor.
However, At kernel version 4.9 or 4.14, the frequency fixed at 177000000 with 'Simple_ondemand' GPU governor.

In addition, as the thermal increases above 90'C, the DVFS works with throttle at v3.10
However, at v 4.14, the frequency continuously fixed. As the thermal increases above 105'c, the sensor just show fixed temperature 100'c
@dongkwan,
Oh, I see.
Thank you for sharing the detailed information.

I will try to reproduce the issue
and check it on kernel 3.10 and 4.14.
I think other users need this, too.

dongkwan
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Re: [Q] XU4 Mali GPU frequency scaling (DVFS)

Unread post by dongkwan » Fri Nov 01, 2019 8:06 pm

I apologized about this topic.
I executed a hard work of OpenCL at XU4 4.14, again.
Then the DVFS(simple_ondemand) is working well.
I'm really sorry.

I will check the throttle above 100C. Maybe, I did a wrong experiment...
These users thanked the author dongkwan for the post (total 2):
odroid (Sat Nov 02, 2019 9:55 am) • joy (Mon Nov 11, 2019 10:01 am)

joy
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Re: [Q] XU4 Mali GPU frequency scaling (DVFS)

Unread post by joy » Mon Nov 11, 2019 10:11 am

@dongkwan,
Also I didn't keep following this thread and verifying its operation and show you my test result once I've checked once it works, so I'm sorry, too.

Thank you for sharing your test status and confirming its operation on XU4 4.14 kernel.
This information is very helpful for other users. ;)

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