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On Sat, May 3, 2014 at 10:16 AM, Chris Stankevitz wrote:
> Hello,
>
> I have a small system:
>
> - 6GB drive
>
> - ext4 partition mounted readonly
>
> - swap partition that is not listed in fstab and not enabled. (I will
> swapon it every few weeks or so if I need it for a large compile job)
>
> - 2 GB RAM
>
> When the system boots it processing video from a USB camera. The
> program dynamically allocates and releases memory while it runs, but
> stores no data in memory or on disk (read-only). The memory usage
> does not grow over time.
>
> When things are going well, top looks like so:
>
> ===
>
> Tasks: 68 total, 1 running, 67 sleeping, 0 stopped, 0 zombie
> %Cpu0 : 88.3 us, 11.7 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 0.0 si,
> 0.0 st
> %Cpu1 : 25.5 us, 2.3 sy, 0.0 ni, 72.1 id, 0.0 wa, 0.0 hi, 0.0 si,
> 0.0 st
> %Cpu2 : 6.0 us, 0.7 sy, 0.0 ni, 93.3 id, 0.0 wa, 0.0 hi, 0.0 si,
> 0.0 st
> %Cpu3 : 25.7 us, 2.3 sy, 0.0 ni, 72.0 id, 0.0 wa, 0.0 hi, 0.0 si,
> 0.0 st
> KiB Mem: 1861644 total, 161648 used, 166 free, 6948 buffers
> KiB Swap:0 total,0 used,0 free,57728 cached
>
> PID USER PR NIVIRTRESSHR S %CPU %MEM TIME+ COMMAND
> 2129 root 20 0 1774440 81712 25388 S 160.0 4.4 25:55.46 obt
> 705 root 20 0 0 0 0 S 1.0 0.0 0:07.87 kswapd0
> 2049 ueyed 20 0 620472 14092 13652 S 1.0 0.8 0:09.34
> ueyeusbd
>
>
>
>
>
> Q1: Why does the kswapd0 process from time to time take up 100% CPU?
>
> Q2: Why does top show "cached swap" eventhough I do not have swap mounted?
>
> Q3: Is there anything I can do to prevent kswapd0 from using CPU on my
> system? e.g. disable SWAP in the kernel config
>
> I suspect the answer to Q1 is:
>
> a) kernel is not configured properly for my hardware
> or
> b) there is some bad side effect to my readonly root fs
>
> Thank you,
>
> Chris
>
>
