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JOURNAL FOR THURSDAY 20TH DECEMBER, 2012
______________________________________________________________________________
SUBJECT: Minimal Linux for running dedecated WolfMUD server
DATE: Thu Dec 20 22:35:53 GMT 2012
As I've been working with resource constrained ARM systems lately it gave me
reason to wonder how much Linux do you actually need running in order to
'play' WolfMUD?
I started with a standard QEMU setup: versatilepb running Debian and 256Mb RAM
allocated. A standard boot looks like:
$ ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 1.0 0.2 2128 724 ? Ss 21:59 0:01 init [2]
root 2 0.0 0.0 0 0 ? S 21:59 0:00 [kthreadd]
root 3 0.4 0.0 0 0 ? S 21:59 0:00 [ksoftirqd/0]
root 4 0.2 0.0 0 0 ? S 21:59 0:00 [kworker/0:0]
root 5 0.0 0.0 0 0 ? S 21:59 0:00 [kworker/u:0]
root 7 0.0 0.0 0 0 ? S< 21:59 0:00 [cpuset]
root 8 0.0 0.0 0 0 ? S< 21:59 0:00 [khelper]
root 9 0.0 0.0 0 0 ? S 21:59 0:00 [kdevtmpfs]
root 10 0.0 0.0 0 0 ? S< 21:59 0:00 [netns]
root 11 0.0 0.0 0 0 ? S 21:59 0:00 [sync_supers]
root 12 0.0 0.0 0 0 ? S 21:59 0:00 [bdi-default]
root 13 0.0 0.0 0 0 ? S< 21:59 0:00 [kintegrityd]
root 14 0.0 0.0 0 0 ? S< 21:59 0:00 [kblockd]
root 15 0.0 0.0 0 0 ? S 21:59 0:00 [khungtaskd]
root 16 0.0 0.0 0 0 ? S 21:59 0:00 [kswapd0]
root 17 0.0 0.0 0 0 ? SN 21:59 0:00 [ksmd]
root 18 0.0 0.0 0 0 ? S 21:59 0:00 [fsnotify_mark]
root 19 0.0 0.0 0 0 ? S< 21:59 0:00 [crypto]
root 22 0.0 0.0 0 0 ? S 21:59 0:00 [kworker/0:1]
root 23 0.3 0.0 0 0 ? S 21:59 0:00 [kworker/0:2]
root 62 0.0 0.0 0 0 ? S 21:59 0:00 [scsi_eh_0]
root 99 0.0 0.0 0 0 ? S 21:59 0:00 [kworker/u:1]
root 114 0.0 0.0 0 0 ? S 21:59 0:00 [jbd2/sda1-8]
root 115 0.0 0.0 0 0 ? S< 21:59 0:00 [ext4-dio-unwrit]
root 191 0.0 0.0 0 0 ? S 21:59 0:00 [flush-8:0]
root 245 0.5 0.4 2784 1048 ? Ss 21:59 0:00 udevd --daemon
root 303 0.0 0.0 0 0 ? S< 21:59 0:00 [kpsmoused]
root 614 0.0 0.2 2780 680 ? S 21:59 0:00 udevd --daemon
root 616 0.0 0.3 2780 784 ? S 21:59 0:00 udevd --daemon
root 1516 0.0 0.7 4892 2004 ? Ss 22:00 0:00 dhclient -1 -v -pf
root 1699 0.5 0.6 27980 1536 ? Sl 22:00 0:00 /usr/sbin/rsyslogd
daemon 1757 0.0 0.1 2112 316 ? Ss 22:01 0:00 /usr/sbin/atd
root 1767 0.1 0.3 3780 796 ? Ss 22:01 0:00 /usr/sbin/cron
root 1865 0.1 0.4 6268 1044 ? Ss 22:01 0:00 /usr/sbin/sshd
root 2074 4.3 1.1 9444 2916 ? Ss 22:01 0:01 sshd: diddymus [pri
101 2085 0.1 0.3 7760 944 ? Ss 22:01 0:00 /usr/sbin/exim4 -bd
root 2113 0.3 0.3 3724 812 tty1 Ss+ 22:01 0:00 /sbin/getty 38400 t
diddymus 2114 0.9 0.7 9444 1824 ? S 22:01 0:00 sshd: diddymus/
diddymus 2115 1.3 0.7 4764 1840 pts/0 Ss 22:01 0:00 -bash
diddymus 2123 0.0 0.4 4436 1124 pts/0 R+ 22:01 0:00 ps aux
$ free -h
total used free shared buffers cached
Mem: 249M 37M 212M 0B 6.4M 18M
-/+ buffers/cache: 12M 237M
Swap: 465M 0B 465M
So, not too bad but what if I ONLY wanted to run WolfMUD? A totally dedicated
server. Well we can replace init with something like /bin/sh. We then end up
with:
# ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 2.8 0.2 1732 512 ? S 22:07 0:01 /bin/sh
root 2 0.0 0.0 0 0 ? S 22:07 0:00 [kthreadd]
root 3 0.0 0.0 0 0 ? S 22:07 0:00 [ksoftirqd/0]
root 4 0.2 0.0 0 0 ? S 22:07 0:00 [kworker/0:0]
root 5 0.0 0.0 0 0 ? S 22:07 0:00 [kworker/u:0]
root 6 0.0 0.0 0 0 ? S 22:07 0:00 [watchdog/0]
root 7 0.0 0.0 0 0 ? S< 22:07 0:00 [cpuset]
root 8 0.0 0.0 0 0 ? S< 22:07 0:00 [khelper]
root 9 0.0 0.0 0 0 ? S 22:07 0:00 [kdevtmpfs]
root 10 0.0 0.0 0 0 ? S< 22:07 0:00 [netns]
root 11 0.0 0.0 0 0 ? S 22:07 0:00 [sync_supers]
root 12 0.0 0.0 0 0 ? S 22:07 0:00 [bdi-default]
root 13 0.0 0.0 0 0 ? S< 22:07 0:00 [kintegrityd]
root 14 0.0 0.0 0 0 ? S< 22:07 0:00 [kblockd]
root 15 0.0 0.0 0 0 ? S 22:08 0:00 [khungtaskd]
root 16 0.0 0.0 0 0 ? S 22:08 0:00 [kswapd0]
root 17 0.0 0.0 0 0 ? SN 22:08 0:00 [ksmd]
root 18 0.0 0.0 0 0 ? S 22:08 0:00 [fsnotify_mark]
root 19 0.0 0.0 0 0 ? S< 22:08 0:00 [crypto]
root 22 0.0 0.0 0 0 ? S 22:08 0:00 [kworker/0:1]
root 23 0.1 0.0 0 0 ? S 22:08 0:00 [kworker/0:2]
root 65 0.0 0.0 0 0 ? S 22:08 0:00 [scsi_eh_0]
root 102 0.0 0.0 0 0 ? S 22:08 0:00 [kworker/u:1]
root 118 0.0 0.0 0 0 ? S 22:08 0:00 [jbd2/sda1-8]
root 119 0.0 0.0 0 0 ? S< 22:08 0:00 [ext4-dio-unwrit]
root 129 0.0 0.0 0 0 ? S 22:08 0:00 [flush-8:0]
root 130 0.0 0.3 2908 996 ? R 22:08 0:00 ps aux
# free -h
total used free shared buffers cached
Mem: 249M 8.7M 241M 0B 1.7M 1.8M
-/+ buffers/cache: 5.2M 244M
Swap: 0B 0B 0B
Interesting... we can also run the WolfMUD server. In fact we could even pass
init=/home/diddymus/WolfMUD/bin/server to the kernel. There is only one
problem - networking is not started yet :(
So I created a small script to load the networking module, start networking
and then start the WolfMUD server:
#!/bin/sh
/sbin/modprobe smc91x
/etc/init.d/networking start
/sbin/ifup eth0
/home/diddymus/WolfMUD/bin/server
Passing this to the kernel using init=/home/diddymus/start I have a dedicated
WolfMUD server with very little overhead, and a darn quick boot to... boot! :)
I'd like to take this further and build a sub-minimal install. Just a bootable
kernel and the minimum of executables and libraries. Having Go compiling
static executables is of great benefit here. At the moment /bin/sh is
symlinked to dash. I'm guessing replacing this with busybox or somthing would
be a good idea as well.
Not bad for about an hour's work poking around ;)
--
Diddymus
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