Slow FC4, perhaps swap is to blame

Boris Glawe boris at
Thu Feb 23 19:08:25 UTC 2006

John Degenstein wrote:

>Alright, to begin here are my system specs:
>Athlon 64 3200+
>512 MB PC2100 DDR
>200 GB SATA
>160 GB IDE
>Nvidia GF4 4000 (128MB)

512 MB is ok, but not very much for a 64 Bit Machine. It's not the 
reason for the problem. Also the slower Memory (2100 instead of  3200) 
is not the reason.

>This is a problem I have been trying to fix for several months now,
>and I am pretty sure it is the swap space on this computer has
>something to do with it.  When I first start up the computer it is
>blazing fast, and I have no problem filling 4 workspaces up with
>resource intensive programs.  But as the days and weeks wear on the
>computer gets progressively slower, to the point where simply
>switching between workspaces with only 3 or 4 programs open becomes
>incredibly slow.  The problem also seems to relate to programs that
>use Java, such as azureus and qnext, it seems to me that there is some
>kind of memory leak that builds up in the swap space over time.  Even
>after the swap space has been filled I attempt to clear it by closing
>all open programs, but this has no effect and it is beginning to drive
>me crazy.
>I did manage to find a command which I somehow got to work at least
>several times:
>swapoff -a /dev/logVol00/_something_here

This makes things faster, because you force your machine to use the 
available phyical ram instead of the swap. Your "out of memory " error 
messages are a corollary though if the machine doesn't have any swap space.
Your problem is that some apps eat up all your memory. FC4 should have 
no problems running with 512 MB RAM and no swap.

You have to find the program, which eats up all the memory.

You can use the command top to find that out:
-    run the command 'top'
-    press 'F' (which allows you to choose the sort critieria)
-    Choose RES by pressing 'q'. (RES is the ammount of memory in MByte 
which processes really use.  )
-    press Enter which will bring you back to the process list. The list 
is now sorted by memory usage. See, which process uses all your memory.

I guess, that it's you X Server, which uses all the memory. In this case 
it would help if you simply logged out, which causes the X Server to 
terminate and to release the memory. With the next login your X-Server 
will require only a few MByte RAM.

>This command alleviated my problems immediately, but then I started to
>get errors about running out of memory from new programs I was trying
>to open so I enabled swap again with the command "swapon".  Another
>possible source of my problems is the fact I am running PC2100 DDR
>rather than the minimum that my motherboard supposedly supports,
>PC2700, because of this I had to underclock some of the components on
>my mobo so that the computer would boot.
>So I guess my main question is: is the swap space in Linux messed up,
>or is it simply a problem from Java???
It's the problem of any one process, not necessarily java (though java 
is also a candidate for very high memory usage).

Report us, which application needs such big amounts of memory and we can 
go on in the search for a solution.

greets Boris

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