I have just noticed that I missed to mention one very important thing in my previous post.
File /proc/meminfo contains a very useful field named Committed_AS. This field indicates TOTAL value of committed memory. If all applications would require all memory allocated to them your server would need this amount of memory.
If we look in the example from my previous post we would find following values:
loreto:/tmp # cat /proc/meminfo
MemTotal:Â Â Â Â Â 33274944 kB
Committed_AS:Â 49751960 kB
So my server has 32GB of RAM, but total amount of memory allocated is 48GB. That is 150%! If all this memory would be required at once server would crash pretty bad (or OOM killer would start butchering my Oracle databases to get some memory back!). :-)