[sf-lug] sf-lug Digest, Vol 31, Issue 20

[Asheesh Laroia]

On Mon, 9 Jun 2008, Rick Moen wrote:

> Yesterday, I wrote:
>
>> Particularly on a RAM-constrained machine:
>>
>> o  You need to know _why_ you're running each process (i.e., know what
>>    happens if you kill it, and know why that would be A Bad Thing).
>
> I really should have elaborated on the above, and will do so now:
>
> Let's say (and this particular example happens _a great deal_ on low-RAM
> systems you've just installed Debian onto someone's 64MB RAM P200 laptop,
> and the output of "ps auxw | more" (the process table) includes a line
> for process "portmap", something like this:
>
> daemon   11064  0.0  0.1   1664   456 ?        Ss   May22   0:00 /sbin/portmap
>
> The laptop's running OK, and you're thinking:  I don't know much about
> "portmap", and don't know if it's a needed process or not.  How do I tell?
>
> Good question.  The way you tell is:  Kill it ("killall portmap", run as
> the root user), make sure the process is indeed gone, and see if
> anything is no longer working that you care about.

A recovering Solaris sysadmin I know (migrating to Linuxland) tried this 
trick for kjournald.

(This is the "kernel thread" that handles journaling to an ext3 
filesystem.)

It was using up lots of CPU time and doing LOTS of disk I/O!

When it failed to die from a kill, he kill -9'd it.  Hilarity ensued.

(I found out about it when he emailed a bunch of Linux-using students to 
ask what was up.)

-- Asheesh.

P.S. Attentive readers will note that I am not contradicting Rick, simply 
providing a case where his advice does not apply to a *different 
situation* (this was not a teensy laptop).

-- 
The wonderful thing about a dancing bear is not how well he dances,
but that he dances at all.