Machine not freeing Cached Memory?

From: Paul Sargent (Paul.Sargent@3dlabs.com)
Date: Fri Apr 26 2002 - 06:34:59 EST


Hi There,

I'm having some VM problems. I wonder if anybody can help.

I've got a box here that currently reports....

holly:~/linux-2.4.14# free -tm
             total used free shared buffers cached
Mem: 3021 1041 1980 0 4 885
-/+ buffers/cache: 151 2870
Swap: 3905 126 3779
Total: 6927 1167 5759
             
As you can see, it's a 3G physical RAM box. Currently it's sitting there
with 885MB of Memory labeled as Cache, but if I run a process which requires
lots of memory, then the system seems to prefer swapping, rather than
freeing up the cache memory. For example...

             total used free shared buffers cached
Mem: 3021 3019 2 0 1 845
-/+ buffers/cache: 2172 849
Swap: 3905 488 3417
Total: 6927 3508 3419
             
Yes, some 40MB of cache gets freed, but it's mainly (300MB) of swap that
gets used. This tends to slow down processes before they need to because the
machine is thrashing (and I mean really hammering) swap.

Anyone got any ideas?

Kernel is 2.4.14, and it's a debian woody installation.

Is a later version of 2.4 likly to help me here?

Cheers

Paul

-- 
Paul Sargent
mailto: Paul.Sargent@3Dlabs.com
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