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Re: Disk i/o overloading and cpu monitoring

El Lunes, 27 de Diciembre de 2004 16:37, Pol escribió:
> Hi all,
> I am running deb/unstable with kde 3.3.1 gui on my acer
> travelmate laptop (intel centrino cpu).
> In the last few days, my laptop has become almost unusable
> due to overloading input/output to the disk, that seems
> to be triggered both by desktop applications (e.g.kpackages,
> kaffeine, etc) and terminal applications entered  through
> the konsole terminal emulation, e.g. apt-get, that freezes
> reading the database.
> As I have checked out, enough free swap area seems to be
> available, so no reason of such i/o is evident.

To fire disk i/o activity this is the perfect reason. You have swap area 
available, and the kernel wants to use it. Look what effect has setting
/proc/sys/vm/swappiness. 0 -> almost no swap use, 100 -> everything to swap 
quickly. Remember no swap means no disk cache in memory.

> Furthermore, from the system monitor on the kde panel
> displays one gets that almost 100% cpu is busy due to system
> activity, while 'top' is detecting a very low cpu
> activity - i cannot explain such inconsistent behaviour.
> Here are my questions:
>   - What can be the origin of such high i/o traffic?

May be the loggin system? Sometimes famd goes crazy to the 100% and I have to 
restart it.

>   - Why do the kde panel and 'top' report such different informations?

That is very strange. May be in top you do not calculate the total sum for all 

>   - How can i detect the program (system processes behind
>     the running desktop  application) that is actually performing i/o ?

Sure there is a better way, but, a

lsof -n | grep / | grep -v /proc | grep -v /lib/ | less 

will tell you all open files. May be it gives you a clue.

I have read several times for laptops you should mount fs without atime, 
disable kernel logging, and tune syslog via /etc/syslog.conf

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