Ping'i degistirip milisaniye yerine microsaniye hassasiyetinde
degerler dondurmesini sagladim (tezim icin gerekli). Asagida ornek
cikti var:
-----------------------------------------------------------------
64 bytes from 193.140.250.50: icmp_seq=4976 ttl=60 time=17619 us
64 bytes from 193.140.250.50: icmp_seq=4977 ttl=60 time=37598 us
64 bytes from 193.140.250.50: icmp_seq=4978 ttl=60 time=37901 us
64 bytes from 193.140.250.50: icmp_seq=4979 ttl=60 time=67165 us
64 bytes from 193.140.250.50: icmp_seq=4980 ttl=60 time=54299 us
64 bytes from 193.140.250.50: icmp_seq=4981 ttl=60 time=96715 us
64 bytes from 193.140.250.50: icmp_seq=4982 ttl=60 time=17397 us
64 bytes from 193.140.250.50: icmp_seq=4983 ttl=60 time=17470 us
64 bytes from 193.140.250.50: icmp_seq=4984 ttl=60 time=17197 us
------------------------------------------------------------------
Simdi olay micro saniye mertebesinde olunca eminim bu degerler
sistemdeki CPU yukune bagli olarak degisiyordur. Ama bana
4 microsaniye hassasiyet gerekli.
$unu yapsam diyorum: Linux'taki gereksiz processleri oldurup
sadece benim ping programini calistirsam? Ondan sonra
bir kalibrasyon yapsam. Peki kesin calismak zorunda olan process'ler
var mi? Gocmesin sonra makine?
Benim makinada calisan process listesi (ps aux) soyle (tipik zaten):
----------------------------------------------------------------------------------
USER       PID %CPU %MEM  SIZE   RSS TTY STAT START   TIME COMMAND
bin         83  0.0  0.2   848   304  ?  S  Jan 12   0:00 /usr/sbin/rpc.portmap 
nobody     112  0.0  0.5  1108   648  ?  S  Jan 12   0:00 /usr/sbin/httpd 
nobody     113  0.0  0.5  1108   640  ?  S  Jan 12   0:00 /usr/sbin/httpd 
nobody     114  0.0  0.4  1084   556  ?  S  Jan 12   0:00 /usr/sbin/httpd 
nobody     115  0.0  0.4  1084   552  ?  S  Jan 12   0:00 /usr/sbin/httpd 
nobody     116  0.0  0.5  1108   648  ?  S  Jan 12   0:00 /usr/sbin/httpd 
nobody    7988  0.0  0.4  1084   576  ?  S  Jan 17   0:00 /usr/sbin/httpd 
nobody   12844  0.0  0.4  1084   560  ?  S  Jan 22   0:00 /usr/sbin/httpd 
root         1  0.0  0.2   848   340  ?  S  Jan 12   0:26 init [3] 
root         2  0.0  0.0     0     0  ?  SW Jan 12   0:00 (kflushd)
root         3  0.0  0.0     0     0  ?  SW<Jan 12   0:00 (kswapd)
root         4  0.0  0.0     0     0  ?  SW Jan 12   0:00 (nfsiod)
root         5  0.0  0.0     0     0  ?  SW Jan 12   0:00 (nfsiod)
root         6  0.0  0.0     0     0  ?  SW Jan 12   0:00 (nfsiod)
root         7  0.0  0.0     0     0  ?  SW Jan 12   0:00 (nfsiod)
root        13  0.0  0.1   824   252  ?  S  Jan 12   0:01 /sbin/update 
root        14  0.0  0.2   836   300  ?  S  Jan 12   0:00 /sbin/kerneld 
root        80  0.0  0.3   856   388  ?  S  Jan 12   0:13 /usr/sbin/syslogd 
root        81  0.0  0.4  1104   556  ?  S  Jan 12   0:01 /usr/sbin/klogd 
root        85  0.0  0.2   848   368  ?  S  Jan 12   0:00 /usr/sbin/inetd 
root        87  0.0  0.2   864   316  ?  S  Jan 12   0:00 /usr/sbin/lpd 
root        90  0.0  0.3   880   396  ?  S  Jan 12   0:00 /usr/sbin/rpc.mountd 
root        92  0.0  0.3   916   404  ?  S  Jan 12   0:00 /usr/sbin/rpc.nfsd 
root        94  0.0  0.2   844   324  ?  S  Jan 12   0:00 /usr/sbin/crond -l10 
root       100  0.0  0.5  1268   724  ?  S  Jan 12   0:00 sendmail: 
root       107  0.0  0.2   840   296   3 S  Jan 12   0:00 /sbin/agetty 38400 tty3
root       108  0.0  0.2   840   296   4 S  Jan 12   0:00 /sbin/agetty 38400 tty4  
root       109  0.0  0.2   840   296   5 S  Jan 12   0:00 /sbin/agetty 38400 tty5
root       110  0.0  0.2   840   284   6 S  Jan 12   0:00 /sbin/agetty 38400 tty6
root       111  0.0  0.4  1084   552  ?  S  Jan 12   0:00 /usr/sbin/httpd 
root      2096  0.0  0.4  1172   616   1 S  Jan 13   0:00 -bash 
------------------------------------------------------------------------------------
Bunlarin bircogu oldurulebilir. Fakat bazilarindan supheliyim 
mesela: init [3], (kflushd), (kswapd), /sbin/update, /sbin/kerneld,
/usr/sbin/syslogd, /usr/sbin/crond -l10 ... gibi.
Aslinda bunlarin tam ne oldugunu bilmedigim supheliyim. Linux'ta olmazsa
olmaz process'ler var midir? Varsa nelerdir? 
Umarim acik olmustur. Yardimci olursaniz sevinirim.
Saygi&Sevgi.
Pars Mutaf
Izmir Yuksek Teknoloji Enstitusu
 
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