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There is plenty of free ram, but the kernel prefers to swap unused pages to disk. And later I have to wait for them to be unswapped, the Desktop looses its promptness - annoying.
This is a bug in the -34 and -34.0.1 kernels and possibly 1 or 2 before that. Systems under load swap prematurely. You can install the test kernel from the dev tree which will be in the upcoming 4.4 release. Your issue is fixed in that kernel.
You may also want to set 'vm.swappiness = 10' or so in /etc/sysctl.conf (reread without rebooting with sysctl -p)
The lower the number (0-100) you set for swappiness, the less willing your system will be to swap. No setting it to 0 will not keep your system from swapping at all.
In win2k and winXP there is a registry key property which prevents swapping while there is still RAM.
Do you know whether I can achieve the same in linux?