Linux like dmesg in Freebsd

In my previous post, I was talking about the "dmesg -c" equivalent in FreeBSD. Simply it was a sysctl command. So, I decided to simply change FreeBSD dmesg command and make it act like in as Linux. All you have to do is download my patch and apply it as shown below.I was tested the patch on FreeBSD 9 btw.

mybsd# pwd
/usr/src/sbin/dmesg
mybsd# patch < dmesg.patch 
Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|--- dmesg.c.org        2012-01-03 19:04:44.000000000 +0200
|+++ dmesg.c    2012-02-28 11:36:22.000000000 +0200
--------------------------
Patching file dmesg.c using Plan A...
Hunk #1 succeeded at 81.
Hunk #2 succeeded at 194.
Hunk #3 succeeded at 204.
done
mybsd# make 
Warning: Object directory not changed from original /usr/src/sbin/dmesg
cc -O2 -pipe  -std=gnu99 -fstack-protector -Wsystem-headers -Werror -Wall -Wno-format-y2k -W -Wno-unused-parameter -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow -Wunused-parameter -Wcast-align -Wchar-subscripts -Winline -Wnested-externs -Wredundant-decls -Wold-style-definition -Wno-pointer-sign -c dmesg.c
cc -O2 -pipe  -std=gnu99 -fstack-protector -Wsystem-headers -Werror -Wall -Wno-format-y2k -W -Wno-unused-parameter -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow -Wunused-parameter -Wcast-align -Wchar-subscripts -Winline -Wnested-externs -Wredundant-decls -Wold-style-definition -Wno-pointer-sign  -o dmesg dmesg.o -lkvm

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Clearing FreeBSD Kernel Message Buffer

As you can clear kernel message buffer on Linux with dmesg command " dmesg -c ", it's a little bit different on a BSD system.It's done by sysctl as following

# sysctl kern.msgbuf_clear=1

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Boosting Radware Defense Pro's performance ;)

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Detailed network interface statistics on Linux

Here is a helpful command for getting interface statistics on your linux box. It's called ip. It's bundled with iproute package. You can see information about dropped, collisions,crc,transmit and other info about your network interface.

root@helga:~# ip -s -s link show eth0
2: eth0:  mtu 1500 qdi
WN qlen 1000
  link/ether 00:24:8c:d5:6a:a7 brd ff:ff:ff:ff:ff:ff
  RX: bytes  packets  errors  dropped overrun mcast
  1633058095 16933162 0       0       0       0    
  RX errors: length  crc     frame   fifo    missed
             0        0       0       0       0    
  TX: bytes  packets  errors  dropped carrier collsns
  1994496524 5588574  0       0       0       0    
  TX errors: aborted fifo    window  heartbeat
             0        0       0       0    

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I/O usage per process on Linux

Linux kernel 2.6.20 and later supports per process I/O accounting. You can access every process/thread's I/O read/write values by using /proc filesystem. You can check if your kernel has built with I/O account by just simply checking /proc/self/io file. If it exists then you have I/O accounting built-in.

$ cat /proc/self/io
rchar: 3809
wchar: 0
syscr: 10
syscw: 0
read_bytes: 0
write_bytes: 0
cancelled_write_bytes: 0

Field Descriptions:

rchar  - bytes read
wchar  - byres written
syscr  - number of read syscalls
syscw  - number of write syscalls
read_bytes  - number of bytes caused by this process to  read
            from underlying storage
write_bytes - number of bytes caused by this process to written from
            underlying storage

As you know, ever process is presented by it's pid number under /proc directory. You can access any process's I/O accounting values by just looking /proc/#pid/io file. There is a utility called iotop which collects these values and shows you in like top utility. You see your processes I/O activity with iotop utility.

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problem compiling Mysql 5.1 with sphinx engine support

Mysql's full-text search engine is not very powerful and support comes only with Myisam engine. Sphinx is a full-text search engine replacement for Mysql and Postgresql. Also, It's possible to use Sphinx full-text search engine with both Myisam and InnoDB engines. You can read detailed information about mysql compilation with sphinx on Sphinx site.

I have faced with following error message, while compiling Mysql with innodb and sphinx engine support ( ./configure --prefix=/data/mysql3/ --with-plugins=sphinx,innobase). I used the innodb (base) which bundled with Mysql. You can also compile innodb plugin which has additional features. For example, on the fly compression, speed improvements.

configure: error: unknown plugin: sphinx

The trick was to run autorun.sh command in Mysql's source tree before running configure with sphinx engine support. This script will create a new configure script which knows how to compile sphinx engine.

# ./BUILD/autorun.sh

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nethogs network utility

Nethogs is a small but very useful utility, if you like to see your machine's bandwidth usage per processes. Here is a simple screenshot from my linuxbox.

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