[UPDATE] Get to know and Control big.LITTLE

[mdrjr]

Obligatory reading:

Code: Select all

Q: What's a cluster
A: The Exynos 5410 SoC has two CPU Clusters:
    - One CPU cluster has 4 ARMv7-a Cortex-A7 cores running at a max frequency of 1.2Ghz, those 4-cores share a 256Kbyte L2 cache
    - One CPU cluster has 4 ARMv7-a Cortex-A15 cores running at a max frequency of 1.6Ghz(1.8Ghz Overclock), those 4-cores share a 2Mbyte L2 cache

1. Identify what CPU Cluster you are using.

Its very simple..

grep "CPU part" /proc/cpuinfo

if CPU part is 0xc07 them you are on the Little cores.. the A7's
if CPU part is 0xc0f them you are on the big cores.. the A15's

Hope it clarify for people asking on what cores they are



2. Read big.LITTLE status

Another easy thing to do!

cat /dev/bL_status

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        0 1 2 3 L2 CCI
[A15]   0 0 0 0  0
[A7]    0 0 0 1  1

You'll what cores of the 4-cores of each cluster is alive and where l2 is 1 its the alive cluster


3. Control big.LITTLE

Modes are:

Code: Select all

00 - disables the cluster switching
01 - LITTLE only (only a7 cores)
11 - enables big.LITTLE cluster migration

BIG NOTE: BEFORE Switching between big and LITTLE manually, PLEASE disable cluster switching otherwise your board will lock and requires a reboot.

BIG NOTE2: Make sure that you are on ondemand governor!!!!!!!!!!
echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor


control method..

echo value > /dev/b.L_operator
example: echo 00 > /dev/b.L_operator


Small note: There's an extra mode.. 10 - big only, however its ignored by code, so, if you want purely A15 cores, switch to performance governor!



4. Benchmark Tests

My Setup:

Processor: ARMv7 rev 2 @ 1.80GHz (4 Cores), Motherboard: ODROIDXU, Memory: 2048MB, Disk: 40GB DSA2CT040G3 + 128GB Ext Hard Disk + 2GB uSD
OS: Ubuntu 13.10, Kernel: 3.4.5 (armv7l), Compiler: GCC 4.8, File-System: ext4, Screen Resolution: 1280x800

Ubuntu 13.10 with an UNMODIFIED kernel from the built in kernels

Phoronix Test Suite C-Ray 1.1 (Lower is better)

- A7 Only

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C-Ray 1.1:
    pts/c-ray-1.1.0
    Test 1 of 1
    Estimated Trial Run Count:    3
    Estimated Time To Completion: 14 Minutes
        Started Run 1 @ 06:18:03
        Started Run 2 @ 06:24:26
        Started Run 3 @ 06:30:47  [Std. Dev: 0.47%]

    Test Results:
        380.059
        377.929
        376.511

    Average: 378.17 Seconds

- A15 only

Code: Select all

C-Ray 1.1:
    pts/c-ray-1.1.0
    Test 1 of 1
    Estimated Trial Run Count:    3
    Estimated Time To Completion: 17 Minutes
        Started Run 1 @ 06:42:02
        Started Run 2 @ 06:44:14
        Started Run 3 @ 06:46:22  [Std. Dev: 1.95%]

    Test Results:
        128.708
        125.254
        123.953

    Average: 125.97 Seconds

7-Zip Compression 9.20.1 (higher is better)

- A7 only

Code: Select all

7-Zip Compression 9.20.1:
    pts/compress-7zip-1.6.0
    Test 1 of 1
    Estimated Trial Run Count:    3
    Estimated Time To Completion: 4 Minutes
        Started Run 1 @ 07:07:47
        Started Run 2 @ 07:11:36
        Started Run 3 @ 07:15:24  [Std. Dev: 1.91%]

    Test Results:
        862
        866
        836

    Average: 855 MIPS

- A15 only

Code: Select all

7-Zip Compression 9.20.1:
    pts/compress-7zip-1.6.0
    Test 1 of 1
    Estimated Trial Run Count:    3
    Estimated Time To Completion: 4 Minutes
        Started Run 1 @ 06:59:13
        Started Run 2 @ 07:00:22
        Started Run 3 @ 07:01:32  [Std. Dev: 0.69%]

    Test Results:
        3119
        3162
        3145

    Average: 3142 MIPS

[janrinze]

Thanks! that is really nice to know.

[sert00]

wow!great to see this!Now the only thing missing is xu..tracking say it had to be arrived on 25..but nothing.hpe fedex will bring it here tomorrow!it's 20 days i'm without it,and excited to try this thing soon with the lcd kit i ordered too!
Question-also before,with performance governor,only a15 wrked..or it's something added nw in commits you inserted?I'd plan to use only big clusters..

[mdrjr]

wow!great to see this!Now the only thing missing is xu..tracking say it had to be arrived on 25..but nothing.hpe fedex will bring it here tomorrow!it's 20 days i'm without it,and excited to try this thing soon with the lcd kit i ordered too!
Question-also before,with performance governor,only a15 wrked..or it's something added nw in commits you inserted?I'd plan to use only big clusters..

Its the standard behave of the performance governor
It will move directly to the A15's

[sert00]

ok,thanks!

[d-extremex]

newbie question.

to set to use purely A15 cores,

is this correct

echo 00 > /dev/b.L_operator
echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo 10 > /dev/b.L_operator

and how to keep the setting after a reboot

cheers

[sert00]

do a init.d script..

[mdrjr]

newbie question.

to set to use purely A15 cores,

is this correct

echo 00 > /dev/b.L_operator
echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo 10 > /dev/b.L_operator

and how to keep the setting after a reboot

cheers

That's not a noob question. Its a lazy person who didn't read the text question..
echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

only this line is enough..

[Goerlitzer]

Just see that the terminal program "nmon" (sudo apt-get install nmon) shows if you press "r" every two (or one if you press "-") second which cpu is used. It's a great simple tool to see what's going on on your machine (cpu, sd-/eMMC-cards, network etc.) without stressing the cpu.

[memeka]

From git odroidxu-next:

ARM: EXYNOS: add Exynos Dual Cluster Support …
Add EDCS(Exynos Dual Cluster Support) for Samsung Exynos5410 SoC.
This enables all 8 cores, 4 x A7 and 4 x A15 run at the same time.

Is this working?

[mdrjr]

From git odroidxu-next:

ARM: EXYNOS: add Exynos Dual Cluster Support …
Add EDCS(Exynos Dual Cluster Support) for Samsung Exynos5410 SoC.
This enables all 8 cores, 4 x A7 and 4 x A15 run at the same time.

Is this working?

No and this is not the place to post this.

[memeka]

just a small note:

the L2 is on (1) for the A7 cluster even if A15 is being used.

EDIT: I think this is why I constantly see A7 using 0.01-0.02W of power even though I am running on A15 (which use on idle more than 0.1W)

[usee]

I am running performance tests with Java on a multithreaded application.
With default settings in debian the board does not deliver all performance but it changes frequency and switches cores on and off.
When I apply echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
then the board uses all A15 cores at 1600 GHz.
Shall the board deliver 1800 GHz if I do the following:
echo 1800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq?
Is it safe to the above?

[usee]

Thanks @memeka, it is so one must first type 'sudo su' prior one can echo performance governor.

And it is not possible to set scaling_cur_freq, instead it shows what frequency the board is now using.
I overclocked the board to 1.8 GHz by setting the min to same value with max as follows:
#cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
Then the board gives the best performance so far in my test. I inspect the used frequency as follows:
#cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
1800000

I think that this is the max that I will test. The board behaves so that, when it is under load and gets
hot it is swithes cores on and off while keeping the frequency. For instance
#cat /dev/bL_status
0 1 2 3 L2 CCI
[A15] 1 1 0 1 1
[A7] 0 0 0 0 0

So, I set the min frequency now back to original value.
Thanks, for the information that is given under this topic!

[roosemberth]

Is it possible to get to 2GHz with an excelent cooling system?, which are the barriers? just Thermal Throttling? or there are more limitators?

[memeka]

Thanks @memeka, it is so one must first type 'sudo su' prior one can echo performance governor.

And it is not possible to set scaling_cur_freq, instead it shows what frequency the board is now using.
I overclocked the board to 1.8 GHz by setting the min to same value with max as follows:
#cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
Then the board gives the best performance so far in my test. I inspect the used frequency as follows:
#cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
1800000

I think that this is the max that I will test. The board behaves so that, when it is under load and gets
hot it is swithes cores on and off while keeping the frequency. For instance
#cat /dev/bL_status
0 1 2 3 L2 CCI
[A15] 1 1 0 1 1
[A7] 0 0 0 0 0

So, I set the min frequency now back to original value.
Thanks, for the information that is given under this topic!

"sudo su" ? that's funny
you can just do "su" and enter root password
or you can enter "sudo bash" and enter user password.

Code: Select all

root@elhokar ~ # echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
root@elhokar ~ # cat /dev/bL_status
        0 1 2 3 L2 CCI
[A15]   1 1 0 1  1
[A7]    0 0 0 0  1

You can see here I don't have "0 0 0 0 0" for A7, the L2 cache is still on.

[usee]

Please, just don't mind how I was writing about sudo and su. I am using different distros and in them behaviour
may vary. I am using Fedora at the moment. In the internet there is enough discussion on sudo and su.

Anyway, the performance tuning is a rich topic. I just need to know enough of it so that I can inspect that different distros
have same parameters. So, I rather leave explanations to be written by such people who know how the frequency management is designed to work and how it is aimed to be tuned. Thanks.

[lizardmech]

Is it possible to get to 2GHz with an excelent cooling system?, which are the barriers? just Thermal Throttling? or there are more limitators?

It appears to have the same voltage as 1.8ghz in the kernel files I found, I can't work out how to set it to 2ghz though, trying to set 2ghz through the kernel or /cpuo/cpufreq/ was ignored. I was able to make a custom kernel that used 1.8ghz on all governors without any issues.

[grsingla]

Hi,

Thanks everyone. I have a odroid XU+E and do the same thing.
I want to run an application only on A7 core and then only on A15 core and compare their performance.
I am not aware of the toolchain as to which software to be used, which language and how to interface it with the board.
Which OS should i use for it?
Can you please guide me through it?

[odroid]

It appears to have the same voltage as 1.8ghz in the kernel files I found, I can't work out how to set it to 2ghz though, trying to set 2ghz through the kernel or /cpuo/cpufreq/ was ignored. I was able to make a custom kernel that used 1.8ghz on all governors without any issues.

Did you guys run XU at 1.8Ghz?
According to our various tests, it was really unstable at 1.8Ghz.

[odroid]

Hi,

Thanks everyone. I have a odroid XU+E and do the same thing.
I want to run an application only on A7 core and then only on A15 core and compare their performance.
I am not aware of the toolchain as to which software to be used, which language and how to interface it with the board.
Which OS should i use for it?
Can you please guide me through it?

Please make your own thread for asking.

BTW, you can use any OS image with the latest Kernel update.

[grsingla]

Hi,

Thanks for helping on how to operate big cores and little cores separately.
I wanted to know are we able to operate the cores within a cluster separately or it supports cluster wise migration only.
Also can we only use IKS or global task scheduling (GTS) is also supported.
And we can operate all the 8 cores at the same time right?

[mdrjr]

GTS isn't possible on Exynos 5410.

Just cluster migration works.

[grsingla]

Hi,

Thanks and all the 8 cores can be operated at the same time other than being operated separately right?

[mdrjr]

Hi,

Thanks and all the 8 cores can be operated at the same time other than being operated separately right?

Nope, it can't.

[grsingla]

Hi,

I have android 4.2.2 on odroid XU+E.
after i write command
cat /dev/bL_status
it gives me an error permission denied.
Can you tell me how to get rid of this error.

[mdrjr]

Hi,

I have android 4.2.2 on odroid XU+E.
after i write command
cat /dev/bL_status
it gives me an error permission denied.
Can you tell me how to get rid of this error.

Run it as root? type su before

[grsingla]

Hi,
Thanks..wen i run only A15 the freq is constant 1600Mhz..does stopping cpu migration and manually controlling the migration using governor turns off the DVFS.

[mdrjr]

Yes.. that's right

[grsingla]

thanks..wen i run A15 freq is 1600Mhz but wen i migrate to A7 manually i was expecting it to show 1200Mhz but still it was showing 1600Mhz.
Can you help me with this?

[sert00]

Why don't you open a 3ad where you ask for help,like odroid and mdrjr already sad you?
and why ask via PM to me,to mdrjr etc..when you already asked the same thing in 2 different 3ads?don't go off-topic everywhere,open a 3ad

[lizardmech]

It appears to have the same voltage as 1.8ghz in the kernel files I found, I can't work out how to set it to 2ghz though, trying to set 2ghz through the kernel or /cpuo/cpufreq/ was ignored. I was able to make a custom kernel that used 1.8ghz on all governors without any issues.

Did you guys run XU at 1.8Ghz?
According to our various tests, it was really unstable at 1.8Ghz.

I never have any trouble at 1.8ghz, I use it as my everyday desktop PC and get weeks of uptime. Maybe exynos5 SoCs vary a lot between production weeks?

[dessa]

What ubuntu version are you running? Something custom?
I'm getting Permission denied with root , 13.10 but got apt-get upgrade earlier.

root@odroid:/home/odroid# echo 1800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
bash: /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq: Permission denied


[quote="mdrjr"]Obligatory reading:

Code: Select all

Q: What's a cluster
A: The Exynos 5410 SoC has two CPU Clusters:
    - One CPU cluster has 4 ARMv7-a Cortex-A7 cores running at a max frequency of 1.2Ghz, those 4-cores share a 256Kbyte L2 cache
    - One CPU cluster has 4 ARMv7-a Cortex-A15 cores running at a max frequency of 1.6Ghz(1.8Ghz Overclock), those 4-cores share a 2Mbyte L2 cache

[mdrjr]

scaling_cur_freq is readonly!
scaling_max_freq and scaling_min_freq are rw

[dessa]

Of course! Thanks.
Back to 13.10 then. 12.04 allowed to set max, but was keeping it at 1.6

root@odroid-desktop:/home/odroid# echo 1800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
root@odroid-desktop:/home/odroid# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
1600000

[mdrjr]

1.8Ghz only works on ondemand.

[dessa]

Still no love
root@odroid:/sys/devices/system/cpu/cpu0/cpufreq# echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
root@odroid:/sys/devices/system/cpu/cpu0/cpufreq# echo 1800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
root@odroid:/sys/devices/system/cpu/cpu0/cpufreq# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
1600000
root@odroid:/sys/devices/system/cpu/cpu0/cpufreq# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
ondemand
root@odroid:/sys/devices/system/cpu/cpu0/cpufreq#

[dessa]

Both 13.10 and 12.04 did not set max at 1.8, and stuck at 1.6GHz in either ondemand or performance mode.
Is there known version number was capable of running at 1.8GHz ?
Thanks!

[memeka]

if you compile your own kernel you can set up frequency there at up to 2GHz.

[roosemberth]

You should look up for a more efficient cooling solution, Thermal Thottling will cause the processor frequency to drop (until it reaches ~82°C) when it reaches 90°C~95°C, this is software triggered (See HOT_NORMAL_TEMP and HOT_CRITICAL_TEMP in drivers/thermal/exynos_thermal.c). If it gets abode 100°C, It'll drop the freq to 200MHz (AFAIK), and @123°C Hardware-Triggered will power it off if reached.

I was thinking in a water cooling, but the Idea of a leakage freaks me out, I might take the risk through...

Best Regards!

[dessa]

@memeka, I thought this thread was implying stock Ubuntu can be overclocked. Any pointers on where to look for 2GHz unlock for recompile highly appriciated
@roosemberth , thank, just benchmarking now to see how it will stack against Snap Dragon at similar frequency.

[mdrjr]

Gimme a couple of days and I'll check that for you.. not at home ATM

[odroid]

When we tested the over-clocking with 10 XU boards, only 2 boards can run at 1.8Ghz.
Other 8 boards' maximum frequency was only 1.7 or 1.6Ghz.

So 2.0 Ghz over-clocking seems to be almost impossible or extremely rare case.

[memeka]

oh I'm sorry I was talking about the U2

[Bohemund]

Hello,

I get a "bash: /dev/b.L_operator: Permission denied
" on all commands if i execute them with sudo - whats my mistake ?

newbie question.

to set to use purely A15 cores,

is this correct

echo 00 > /dev/b.L_operator
echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo 10 > /dev/b.L_operator

and how to keep the setting after a reboot

cheers

[mdrjr]

You sure that you are running as root ?

[dessa]

mdrjr,
Any luck checking "overclockable" kernel version/availability? I've tried recompile to 3.4.76 - it is still locked to 1.6Ghz. Not quite shire which part unlocks it .
It seems to be checking in multiple places in code so not very obvious. There some legacy Inkernel code as well.

Looks like 3.8, 3.11. 3.12 kernels are not XU compatible yet, no luck booting with it.

Gimme a couple of days and I'll check that for you.. not at home ATM

[roosemberth]

I've seen on github the cpu-freq code: https://github.com/hardkernel/linux/blo ... -cpufreq.c But I can't find where the implementation is...

I was told to check in governors and related, but, I hadn't take a look yet

Best Regards!

[dessa]

I think those are for inkernel old stuff?
Seem that new is here, and some other files in the folder, really spread out accross the files
https://github.com/hardkernel/linux/blo ... ynos5410.c

[mdrjr]

Nope, those instructions still work for XU.. I've just tested.

@roosemberth,

driver/cpufreq/*exynos*.c