In the below 2.6.18 Linux Kernel (Red Hat) server, there is a lot of free memory, but I see some swap is used. I always thought of swap as an overflow when memory has been depleted. Why would it swap with about 7GB (50%) free memory? Swappiness is 60 (default).
Meminfo output:
MemTotal: 16436132 kB
MemFree: 7507008 kB
Buffers: 534804 kB
Cached: 2642652 kB
SwapCached: 39084 kB
Active: 6001828 kB
Inactive: 2532028 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 16436132 kB
LowFree: 7507008 kB
SwapTotal: 2097144 kB
SwapFree: 1990096 kB
Dirty: 236 kB
Writeback: 0 kB
AnonPages: 5353644 kB
Mapped: 45764 kB
Slab: 330660 kB
PageTables: 34020 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 10315208 kB
Committed_AS: 14836360 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 264660 kB
VmallocChunk: 34359472735 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
Hugepagesize: 2048 kB