I've tried to educate Oracle DBAs on why top is wrong and their memory really isn't being used. It's painful and they often refuse to believe that I know what I'm talking about, and that they should use the free -m command to see what memory is actually available for use.<p>Is there any particular reason why Oracle DBAs are less likely to believe this? Perhaps it's because most of them grew up in legacy UNIX environments rather than Linux.
Looks like their site went down, have a mirror:<p><a href="http://webcache.googleusercontent.com/search?q=cache:http://www.linuxatemyram.com/" rel="nofollow">http://webcache.googleusercontent.com/search?q=cache:http://...</a>
<a href="http://webcache.googleusercontent.com/search?q=cache:http://www.linuxatemyram.com/play.html" rel="nofollow">http://webcache.googleusercontent.com/search?q=cache:http://...</a>
The cache can be cleared via `/proc/sys/vm/drop_caches`.<p><a href="http://linux-mm.org/Drop_Caches" rel="nofollow">http://linux-mm.org/Drop_Caches</a>
I found this page because I was pretty confused about these issues, and still am...<p>Question for the crowd: In this site the example given says that in reality there are 869MB of used RAM. I'm comparing this with my VPS values, and would like to know if this is the sum of some column in top. Is it? It looks like it's pretty close to the sum of the SHR column. Does this make sense? Thanks in advance.
I found a good introduction on unix memory caching in chapter 3 (The Buffer Cache) of 'Design of the UNIX Operating System', <a href="http://www.amazon.com/Design-Operating-System-Prentice-Hall-Software/dp/0132017997" rel="nofollow">http://www.amazon.com/Design-Operating-System-Prentice-Hall-...</a> . At least it was good for me (mathematician by training, programmer by profession)