High load on GK802 idle - CPU is 0%, load is 4.0-5.0

[Žydrūnas Urbonas]

Hi,

I have just rolled out Xubuntu 12.04 (from here: http://jas-hacks.blogspot.com/2013/05/imx6-gk802-xubuntu-1204.html).
Made dual-boot, so Xubuntu remains on external card. Boots fine

But I noticed high load immediately after boot while system is idle and nothing goes on:

root@gk802:~# top
top - 01:54:45 up 54 min,  2 users,  load average: 4.99, 4.88, 4.65
Tasks:  89 total,   1 running,  88 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.2%us,  0.4%sy,  0.0%ni, 99.5%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:    831724k total,   132324k used,   699400k free,    15244k buffers
Swap:        0k total,        0k used,        0k free,    71912k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 3058 root      20   0  2144  948  704 R    1  0.1   0:00.06 top
    1 root      20   0  3120 1680  980 S    0  0.2   0:01.51 init
    2 root      20   0     0    0    0 S    0  0.0   0:00.00 kthreadd
    3 root      20   0     0    0    0 S    0  0.0   0:00.88 ksoftirqd/0
    5 root      20   0     0    0    0 S    0  0.0   0:00.19 kworker/u:0
    6 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/0
    7 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/1
    9 root      20   0     0    0    0 S    0  0.0   0:00.00 ksoftirqd/1
   10 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/2
   11 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/2:0
   12 root      20   0     0    0    0 S    0  0.0   0:00.00 ksoftirqd/2
   13 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/3
   14 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/3:0  
   15 root      20   0     0    0    0 S    0  0.0   0:00.00 ksoftirqd/3
   16 root       0 -20     0    0    0 S    0  0.0   0:00.00 khelper
   17 root      20   0     0    0    0 S    0  0.0   0:00.00 kworker/u:1
  302 root      20   0     0    0    0 S    0  0.0   0:00.01 sync_supers
  304 root      20   0     0    0    0 S    0  0.0   0:00.00 bdi-default
  306 root       0 -20     0    0    0 S    0  0.0   0:00.00 kblockd
  337 root       0 -20     0    0    0 S    0  0.0   0:00.00 ata_sff
  348 root      20   0     0    0    0 S    0  0.0   0:00.00 khubd
  365 root     -50   0     0    0    0 D    0  0.0   0:00.00 ipu1_task
  366 root     -50   0     0    0    0 D    0  0.0   0:00.00 ipu1_task
  367 root     -50   0     0    0    0 D    0  0.0   0:00.00 ipu2_task
  368 root     -50   0     0    0    0 D    0  0.0   0:00.00 ipu2_task
  378 root       0 -20     0    0    0 S    0  0.0   0:00.00 l2cap
  382 root       0 -20     0    0    0 S    0  0.0   0:00.00 cfg80211
  469 root       0 -20     0    0    0 S    0  0.0   0:00.00 rpciod
  476 root      -2   0     0    0    0 S    0  0.0   0:00.00 usb_wakeup thre
  478 root       0 -20     0    0    0 S    0  0.0   0:00.00 otg_switch
  482 root      -2   0     0    0    0 S    0  0.0   0:00.00 usb_wakeup thre
  492 root      20   0     0    0    0 S    0  0.0   0:00.00 kswapd0
  493 root      25   5     0    0    0 S    0  0.0   0:00.00 ksmd
  555 root      20   0     0    0    0 S    0  0.0   0:00.00 fsnotify_mark
  569 root       0 -20     0    0    0 S    0  0.0   0:00.00 nfsiod
  575 root       0 -20     0    0    0 S    0  0.0   0:00.00 crypto
 1149 root      20   0     0    0    0 S    0  0.0   0:00.00 kapmd

I also checked the photo at Jas Hacks blog and I can clearly see the same load values in the screenshot (1 minute average load is 5.79): http://3.bp.blogspot.com/-gJVie7ig5nc/UR6qHDhxUnI/AAAAAAAAAJI/-X5PqPdweAs/s1600/CIMG0215.JPG

So the question is: is it some kind of known issue or just invalid load being reported?
If it's an issue - is there a solution?

Thanks!

[Dmitriy B.]

  365 root     -50   0     0    0    0 D    0  0.0   0:00.00 ipu1_task
  366 root     -50   0     0    0    0 D    0  0.0   0:00.00 ipu1_task
  367 root     -50   0     0    0    0 D    0  0.0   0:00.00 ipu2_task
  368 root     -50   0     0    0    0 D    0  0.0   0:00.00 ipu2_task

You have ipuX_tasks in D state all the time, it is a known bug that was fixed by https://github.com/imx6-dongle/linux-imx/commit/b8a4b014ead3840271b00948b4970051b13e4ff2 and recently officially by freescale http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/commit/?h=imx_3.0.35_4.1.0&id=4dcd0c3746c0125b6f78145f75352b32c05b4674

This bug is harmless and only adds 4 to LA value.

Most probably Jas has his own version of kernel based on official freescale sources without adding these patches. Comment at his blog posts or create an github issue here: https://github.com/mtx512/linux-imx/tree/imx_3.0.35_4.1.0

[tosiara]

Hi Dmitriy,

If I now rebuild the kernel using those instructions from wiki:

git clone https://github.com/imx6-dongle/linux-imx.git
cd linux-imx
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- imx6_gk802_defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -j4 uImage
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -j4 modules

Will it contain the mentioned fix?

Thanks

[Dmitriy B.]

Yes, but you will have fairly old kernel (since Jas didnt push his changes to the main repository). Better solution would be ask Jas where to find the latest kernel that he uses, apply any of the two mentioned patches (they do the same) and rebuild.

2013/12/19 tosiara <tos...@gmail.com>

[tosiara]

Hi,

I have re-compiled the kernel from https://github.com/imx6-dongle/linux-imx.git and confirm - that seems to correct the load values:

top - 01:05:37 up 5 min,  2 users,  load average: 1.00, 0.64, 0.30
Tasks:  90 total,   1 running,  89 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us,  0.4%sy,  0.0%ni, 99.6%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:    831724k total,    85712k used,   746012k free,    11428k buffers
Swap:        0k total,        0k used,        0k free,    36928k cached

But still pretty strange there is even 1.0 load when the system is idle...

Would you recommend to recompile some most up-to-date and stable kernel for GK802?

Thanks/Спасибо

[Dmitriy B.]

But still pretty strange there is even 1.0 load when the system is idle...

Check process list for any processes, especially, kernel ones, that got stuck in D or R modes for too long, these are most common reasons for wrong LA values.

Would you recommend to recompile some most up-to-date and stable kernel for GK802?

As I said - best way would be just contact Jas as he is sort of main guy for GK802 development right now and notify him about these two patches. I've added him to Cc: list of this message.