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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