top - 10:18:36 up 2 days, 20:30, 1 user, load average: 0.77, 0.77, 0.50
Tasks: 85 total, 3 running, 82 sleeping, 0 stopped, 0 zombie
Cpu(s): 36.4% us, 13.8% sy, 0.0% ni, 49.8% id, 0.0% wa, 0.0% hi, 0.0% si
Mem: 4151296k total, 4043052k used, 108244k free, 34388k buffers
Swap: 2031608k total, 144k used, 2031464k free, 2913752k cached 想问一下，黑体部分的free表示什么意思？为什么我用2G和4G时的free都是差不多的？