gettimeofday() revisited

Cees de Groot cg at cdegroot.com
Sun May 12 09:20:26 UTC 2002


If anyone still things that calling gettimeofday() multiple thousand times per 
second is a good idea, here is some top output:

 11:18am  up 6 days, 10:57,  1 user,  load average: 0.05, 0.12, 0.39
263 processes: 252 sleeping, 1 running, 10 zombie, 0 stopped
CPU states:  8.7% user, 25.9% system,  0.0% nice, 65.3% idle
Mem:  1029384K av, 1018216K used,   11168K free,       0K shrd,  117660K buff
Swap: 1056124K av,   57280K used,  998844K free                  803368K cached

  PID USER     PRI  NI  SIZE  RSS SHARE STAT  LIB %CPU %MEM   TIME COMMAND
27058 uml0003   17   0  1108 1108  1100 S    1092 25.2  0.1 356:56 linux-vrt-3
18004 uml0003   13   0 29620  28M 29612 S     27M 21.5  2.8 363:31 linux-vrt-3

process 18004 is a Squeak VM inside a user-mode Linux virtual linux machine. 
Process 27058 is the kernel thread that handles all the system calls. A system 
call in user-mode Linux is a context switch, and the result of all the 
gettimeofdays() is that the processor runs hot doing context switches... :-(

So there goes my idea of installing Swiki servers inside user-mode Linux 
virtual machines :-(
-- 
Cees de Groot               http://www.cdegroot.com     <cg at cdegroot.com>
GnuPG 1024D/E0989E8B 0016 F679 F38D 5946 4ECD  1986 F303 937F E098 9E8B





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