[CentOS] CentOS server running java - won't let go of swap

Les Mikesell lesmikesell at gmail.com
Sun Mar 7 19:41:24 UTC 2010

Sean Carolan wrote:
>> I think Xms/x is java's heap space for program object storage.  It doesn't take
>> into account the space needed for the JVM itself.  Top should show you the
>> actual memory usage - along with any other programs that might be using a lot.
> One of our java developers indicated that the heap space plus permgen
> should approximate the total memory required by the JVM.  HP's system
> management homepage that eats up nearly 500MB by itself.

I'm pretty sure that's not true.  Permgen is just part of the heap space and 
none of that accounts for the executing part of the JVM.  In any case, you 
probably want to allow some free memory to be used for filesystem cache.

> Are there any tools that let you look inside  the swap disk or file
> and see exactly what is being placed there?

In top, hit 'f', then 'p' to add a column to show swap usage by process.

   Les Mikesell
    lesmikesell at gmail.com

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