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Hello all,
I bought new CPU and motherboard for my PC. I decided to switch to FM2+ in order to use APU unit. So my CPU consists of graphics card Radeon R7 and 4 CPU threads :
model name : AMD A8-7600 Radeon R7, 10 Compute Cores 4C+6G
using motherboard Asrock A88M-G/3.1
UEFI configuration program reports that CPU can scale up to 3800Mhz, Cool&Quiet is enabled, AMD Turbo Boost is enabled, no overlocking was made, all timings and multipliers are set to AUTO.
It's all working under: Linux linux 4.5.0-1-ARCH #1 SMP PREEMPT Tue Mar 15 09:41:03 CET 2016 x86_64 GNU/Linux
My CPU is scaled automatically by kernel on following frequencies:
available frequency steps: 3.10 GHz, 2.80 GHz, 2.40 GHz, 1.90 GHz, 1.40 GHz
BUT in Turbo mode (http://askubuntu.com/questions/459788/h … untu-14-04) I should have possibility to rise it's frequency up to 3,8GHz. I used
cpupower frequency-info
and I got information that:
boost state support:
Supported: yes
Active: no
So I followed google instructions and I changed my kernel boot parameters, adding radeon.bapm=1 to my /etc/default/grub:
GRUB_CMDLINE_LINUX_DEFAULT="quiet radeon.bapm=1"
then I regenerated grub's config file and reinstalled it according to: https://wiki.archlinux.org/index.php/GR … ll_to_disk
Now I can see that boost is actually supported and active:
[root@linux mk]# cpupower frequency-info
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 4.0 us
hardware limits: 1.40 GHz - 3.10 GHz
available frequency steps: 3.10 GHz, 2.80 GHz, 2.40 GHz, 1.90 GHz, 1.40 GHz
available cpufreq governors: ondemand performance
current policy: frequency should be within 1.40 GHz and 3.10 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency: 1.40 GHz (asserted by call to hardware)
boost state support:
Supported: yes
Active: yes <<<<<<<<<<<<<<<<<<<<<<< HERE
Boost States: 3
Total States: 8
Pstate-Pb0: 3800MHz (boost state)
Pstate-Pb1: 3700MHz (boost state)
Pstate-Pb2: 3300MHz (boost state)
Pstate-P0: 3100MHz
Pstate-P1: 2800MHz
Pstate-P2: 2400MHz
Pstate-P3: 1900MHz
Pstate-P4: 1400MHz
However, it doesn't work. I tested it with mprime torture test and frequency reported by cpupower frequency-info never exceeds 3,1Ghz.
I read further and I found information about BIOS limits (http://webcache.googleusercontent.com/s … clnk&gl=pl). Truely, I have such a limit set, as it can be seen in this file:
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
3100000
So I override this with /etc/modprobe.d/ignore_ppc.conf:
options processor ignore_ppc=1
After that it is even worse: I run mprime and cpupower frequency-info shows me the same output, but current CPU frequency never exceeds 2,4GHz.
So my question is: how to enable Turbo Core on AMD CPU under Linux?
I'm using radeon driver (it's important because it is used by kernel to do the magic).
Last edited by mkkot (2016-04-19 16:12:33)
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I tried again today. cpupower frequency-info doesn't show 2,4GHz but 3,1GHz. I must have done something wrong yesterday. However, still no boost...
// edit
I came to the conclusion that CPU needs to have some free power to "boost" frequency, so I tried with less threads stressing the CPU. I tried with 1, 2 and 3 threads but unfortunately 3,1GHz is the ultimate barrier
// edit
Not hoping for much, I wrote to AMD:
Hello,
I bought your CPU AMD A8 7600 (AD7600YBJABOX), my motherboard is Asrock A88M-G/3.1.
I really didn't expect that my CPU clock frequency will be lowered just because I'm using Linux. My CPU is supposed to go up to 3,8GHz with Turbo Core technology but all I get is 3,1GHz because it seems that something is not properly initialized by radeon driver. Yeah, of course, I could use Catalyst driver, but it's so outdated that it wouldn't work anyway.
I would be happy if some Linux driver developer would take a look and say what is wrong with my approach or provide documentation for open source driver team if Linux kernel is broken at this point:
https://bbs.archlinux.org/viewtopic.php?id=211368
//edit
AMD responded my distribution is not supported. Anyway, I found the problem, it was my approach.
I was checking my CPU frequency with cpupower frequency-info:
current CPU frequency: 1.90 GHz (asserted by call to hardware)
And this wasn't the best idea, I should have used:
watch -n 0,5 cpupower monitor
|Mperf
CPU | C0 | Cx | Freq
0| 10,67| 89,33| 3329
1| 99,50| 0,50| 3362
2| 13,56| 86,44| 1821
3| 13,60| 86,40| 1943
As you can see there, I have 3,3GHz, while my CPU is 3,1GHz. Not much of a boost (using mprime) but at least it works.
Last edited by mkkot (2016-04-19 16:11:56)
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