Why use swap when there is RAM free?

[Vincent Arnoux]

Hi,
Currently, my RAM is used up to 43%, but I still have 5% of my swap
space used. What doesn't linux send the data in swap back to RAM?

top - 15:05:47 up 1 day,  1:44,  1 user,  load average: 0.99, 0.64, 0.48
Tasks: 144 total,   2 running, 142 sleeping,   0 stopped,   0 zombie
Cpu(s): 43.7%us, 38.8%sy,  0.0%ni, 17.4%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   1017396k total,   729396k used,   288000k free,    37636k buffers
Swap:  2000052k total,   109840k used,  1890212k free,   246376k cached



Vincent