Re: cat /dev/hdb > /dev/null DoS

[Denis Vlasenko]

On Friday 09 April 2004 03:10, Sven Köhler wrote:
> > i guess you have DMA enabled on /dev/hdb. I would expect, that the
> > system is at least 50% idle
>
> i did
>    dd if=/dev/hda of=/dev/null bs=1M
> and noticed, that top shows 0% idle, but 95% wa - what ever that means.
>
> Since i've got DMA turned on, i would expect the CPU to be 95% idle,
> instead 95% wa? what does "wa" stand for?

top version? Mine is 2.0.18, looks like this:

 09:47:25  up 1 day, 17:07,  2 users,  load average: 0.42, 0.27, 0.24
116 processes: 114 sleeping, 2 running, 0 zombie, 0 stopped
CPU states:   4.2% user  52.1% system   0.0% nice  43.6% iowait   0.0% idle
Mem:   122736k av,  121088k used,    1648k free,       0k shrd,   22968k buff
        76324k active,              21000k inactive
Swap:   76792k av,   67004k used,    9788k free                   25748k cached

  PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME CPU COMMAND
15022 root      18   0  2280 1460  1200 R    38.6  1.1   0:05   0 dd
-- 
vda
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