【资料整理】对linux内存的理解

$ free -m
total       used       free     shared    buffers     cached
Mem:         32127      24572       7555          0        478      16258
-/+ buffers/cache:       7835      24292
Swap:        20479         97      20382

注意第2行：
实际被程序占用的内存：
-buffers/cache=7835
(used-buffers-cached)  24572-478-16258=7836

实际可用内存总数：
+buffers/cache=24292
(free+buffers+cached)  7555+478+16258=24291

$ free -m
total       used       free     shared    buffers     cached
Mem:         64186        619      63567          0         16         93
-/+ buffers/cache:        509      63677
Swap:        32159          0      32159

实际被程序占用的内存：
-buffers/cache=509

(used-buffers-cached)  619-16-93=510

实际可用内存总数：
+buffers/cache=63677

(free+buffers+cached)  63567+16+93=63676