Re: [gentoo-user] Re: How to find out to what file(...) writes goes on a idle system...

Hi James,

...my board does not use systemd as far as I know...the
whole mimic is original gentoo stage3 stuff and Gentoo
defaults to openrc/udev and not systemd (or am I wrong?)

Cheers
Meino


James <wireless@×××××××××××.com> [14-12-06 21:16]:
>  <meino.cramer <at> gmx.de> writes:
>
>
> > > (1) Then pursue quantifying with tools just what is causing the
> > > writes, strategies for minimization and monitoring as needed.
>
> > > So folks are going down path (1) with you, that is fine.
>
> Prong (1) includes all issues related to systemd. Probably embedded
> experience with systemd is rare, just guessing. Certainly I have none
> of that experience. So post to those iotop responses and remind
> folks you are using systemd on an embedded (gentoo) micro.
>
> root  563  1  0 15:37 ?   00:00:00 /lib/systemd/systemd-udevd --daemon
>
>
>
>
> > > (2) First minimize those write to your non-mechanical memory.
>
> > > I have dozens of tricks to minimize a gentoo system. But it is quite
> > > a bit of work, just so you know. It's not a do this and it great. It
> > > more like, try this, study the result and then alter the strategy.
> > >
> > > hth,
> > > James
> > >
> >
> > Hi,
> >
> > thank you very for all help I received regarding my question.
> >
> > The system is already down to a limit. The by default running
> > processes are:
> >
> > root         1     0  0 15:36 ?        00:00:00 init [3]
> > root         2     0  0 15:36 ?        00:00:00 [kthreadd]
> > root         3     2  0 15:36 ?        00:00:01 [ksoftirqd/0]
> > root         5     2  0 15:36 ?        00:00:00 [kworker/0:0H]
> > root         7     2  0 15:36 ?        00:00:00 [khelper]
> > root         8     2  0 15:36 ?        00:00:00 [kdevtmpfs]
> > root       160     2  0 15:36 ?        00:00:00 [writeback]
> > root       162     2  0 15:36 ?        00:00:00 [crypto]
> > root       164     2  0 15:36 ?        00:00:00 [bioset]
> > root       166     2  0 15:36 ?        00:00:00 [kblockd]
> > root       168     2  0 15:36 ?        00:00:00 [cfg80211]
> > root       169     2  0 15:36 ?        00:00:00 [kworker/0:1]
> > root       280     2  0 15:36 ?        00:00:00 [kswapd0]
> > root       296     2  0 15:36 ?        00:00:00 [fsnotify_mark]
> > root       372     2  0 15:36 ?        00:00:00 [ipv6_addrconf]
> > root       398     2  0 15:36 ?        00:00:00 [deferwq]
> > root       406     2  0 15:36 ?        00:00:12 [mmcqd/0]
> > root       412     2  0 15:36 ?        00:00:00 [kworker/0:2]
> > root       415     2  0 15:36 ?        00:00:00 [jbd2/mmcblk0p2-]
> > root       416     2  0 15:36 ?        00:00:00 [ext4-rsv-conver]
> > root       563     1  0 15:37 ?        00:00:00 /lib/systemd/systemd-udevd
> --daemon
> > root       952     1  0 15:37 ?        00:00:00 /usr/sbin/ifplugd --iface=usb0
> > root      1380     1  0 15:37 ?        00:00:00 /usr/sbin/sshd
> > root      1399     1  0 15:37 tty1     00:00:00 /sbin/agetty 38400 tty1 linux
> > root      1400     1  0 15:37 tty2     00:00:00 /sbin/agetty 38400 tty2 linux
> > root      1401     1  0 15:37 tty3     00:00:00 /sbin/agetty 38400 tty3 linux
> > root      1402     1  0 15:37 tty4     00:00:00 /sbin/agetty 38400 tty4 linux
> > root      1403     1  0 15:37 tty5     00:00:00 /sbin/agetty 38400 tty5 linux
> > root      1404     1  0 15:37 tty6     00:00:00 /sbin/agetty 38400 tty6 linux
> > root      1405     1  0 15:37 ttyS0    00:00:00 /sbin/agetty -L 9600 ttyS0
> vt100
> > root      1406  1380  0 15:37 ?        00:00:02 sshd: root <at> pts/0
> > root      1412  1406  0 15:37 pts/0    00:00:00 screen -R -d
> > root      1414  1412  0 15:37 ?        00:00:01 SCREEN -R -d
> > root      1415  1414  0 15:37 pts/1    00:00:05 -/bin/zsh
> > root      1434     2  0 15:38 ?        00:00:00 [kworker/0:1H]
> > root      1866     2  0 15:43 ?        00:00:00 [kworker/u2:0]
> > root      8556     2  0 16:49 ?        00:00:00 [kworker/u2:2]
>
> I'd research "kworker"
>
> http://askubuntu.com/questions/33640/kworker-what-is-it-and-why-is-it-hogging-so-much-cpu
>
>
> > The count of getty processes may be decreaseable...but the rest is ok,
> > I think.
>
> Those are static and just sitting incase you need a getty, so not a problem
>
> > When I do a ftop I get no process, which have an open file handle for
> > writes...sometimes screen writes to utmp but thats it.
>
> With a traditional (non systemd) approach, init scripts just fire
> up things at boot time and such. With systemd, I have no idea
> what's going on. It's a curious situation and maybe systemd has
> no issue in your excessive writes; pure speculation on my part.
> But an embedded system just sitting idle should use very little
> resource and sit quietly, in my experiences.
>
>
> > I suspect the swapfile I mounted as swapdevice for being guilty.
> > I will deactivate that and we will see then.
>
> good thing to examine.
>
> > When looking at /proc/diskstats: Will I see writes to FIFOs on the
> > disk as writes to the disk???
> > If YES...it would explain it...
>
>
> Also good to look at.
>
> I usually use ext2 or one of the newer files systems, just for solid state
> memory. Here is a good link to get your research your fs options.
>
> http://free-electrons.com/blog/managing-flash-storage-with-linux/
>
> Since you have (2) boards, have you considered installing the second one
> differently (different file system, no systemd  etc etc to compare the
> 2 results?  If you can put different install-varients on different usb/sd/?
> media, then you can just power down and change them out while comparing
> resource utilization; just a thought, but something I do routinely.
>
>
> Also, you need to get a custom/stripped kernel building methodology
> establish so you can try to reduce the kernel size by eliminating things
> you do not use, testing scheduler options and a host of things.
>
> Your entire toolchain needs to be documented and keep track of what
> you change and the results of which test you run, when and such.
>
> Also,  when compiling a kernel for a minimize system I find that using
> (CFLAGS="-Os""  yields faster and small executables) and is an excellent
> way to reduce resource loading on a minimized or embedded system.
>
> It's going to be a long journey, so keep meticulous records of what you
> try, the results and your conclusions for the best path forward.
>
>
> I'm out for a while.
> hth,
> James
>
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