[svlug] Need a good authoritative article.

Florin Andrei florin at andrei.myip.org
Thu Apr 3 13:49:37 PST 2008


James Sparenberg wrote:
> 
>    I fully understand why when I type free on a linux server at best no matter 
> how large the RAM total is, It shows only a few meg free.   I get this part.  
> However I've got a number of computer experts with degree's in Finance (long 
> story) who can't understand why a box with 8G of ram has only 14M free, or a 
> box with 48G of ram and a minimal install only has 172M free.  (obviously I 
> don't know how to configure Linux, and they can't offer any help on what I've 
> done wrong).

Well, why don't you throw a large value in /proc/sys/vm/min_free_kbytes, 
large enough to kill the disk cache, but not too large as to cause 
problems with the applications.
Then bring the "experts" in for a demonstration, show them how crappy 
the performance is, then, in your best Clint Eastwood impersonation, 
proclaim:

#####################################
I know what you're thinking. "Did he install six gigs of RAM or only 
five?" Well, to tell you the truth, in all this excitement I kind of 
lost track myself. But being as this is Linux, the most powerful OS in 
the world, and would blow your head clean off, you've got to ask 
yourself a question: Do I understand what the disk cache is? Well, do 
ya, punk?
#####################################

>    Since I don't have my Finance degree, I've learned it's impossible for me 
> to understand how memory usage works.  So what I'm looking for is a good 
> paper on this topic, probably one that will go so far over the "experts" head 
> that they won't be able to admit it, that covers this topic.

Seems like the walls might be a less tough crowd.

>   Any suggestions as to papers/websites etc that I can point my experts too?

Maybe some links at the bottom of this page could help:

http://www.westnet.com/~gsmith/content/linux-pdflush.htm

-- 
Florin Andrei

http://florin.myip.org/




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