测试程序：
class test
{
public static void main(String[] args)throws Exception{
while(true){
Thread.sleep(1000);
}
}
}
第二部分为下面程序的打印结果：
public class mem {
public static void main(String[] args) throws Exception{
Runtime r = Runtime.getRuntime();
while(true){
System.out.println("free : "+(r.freeMemory()/1024)+"k");
System.out.println("max : "+(r.maxMemory()/1024)+"k");
System.out.println("total: "+(r.totalMemory()/1024)+"k");
Thread.sleep(1000);
}
}
}
下面是使用不同的参数启动后的结果：
1、java test
VIRT RES SHR S %CPU %MEM TIME+ SWAP CODE DATA COMMAND
1211m 10m 6380 S 0.0 0.1 0:00.13 1.2g 68 1.2g java
free : 127847k = 124m
max : 1009792k = 986m
total: 128064k = 125m
2、java -Xmx32m test
VIRT RES SHR S %CPU %MEM TIME+ SWAP CODE DATA COMMAND
216m 9.8m 6384 S 0.0 0.1 0:00.13 206m 68 216m java
free : 4334k = 4m
max : 31616k = 31m
total: 4544k = 4m
3、java -Xms256m -Xmx512m test
VIRT RES SHR S %CPU %MEM TIME+ SWAP CODE DATA COMMAND
697m 10m 6384 S 0.0 0.1 0:00.14 687m 68 697m java
free : 258120k = 252m
max : 504896k = 493m
total: 258560k = 252m
4、java -Xmx1536m test
VIRT RES SHR S %CPU %MEM TIME+ SWAP CODE DATA COMMAND
1726m 9.8m 6384 S 0.0 0.1 0:00.13 1.7g 68 1.7g java
free : 4775k = 4m
max : 1514624k= 1479m
total: 4992k = 4m
5、java -Xms512m -Xmx1024m -Xss128k -Xmn256m -XX:PermSize=16M -XX:MaxPermSize=32M test
VIRT RES SHR S %CPU %MEM TIME+ SWAP CODE DATA COMMAND
1176m 11m 6388 S 0.0 0.1 0:00.14 1.1g 68 1.1g java
free : 487587k = 476m
max : 961216k = 938m
total: 491520k = 480m
Suse系统资源使用情况（相当空闲）：
top - 16:04:54 up 2 days, 7:08, 4 users, load average: 1.02, 1.08, 1.13
Tasks: 111 total, 1 running, 109 sleeping, 1 stopped, 0 zombie
Cpu(s): 0.0% us, 0.0% sy, 0.0% ni, 100.0% id, 0.0% wa, 0.0% hi, 0.0% si
Mem: 8309244k total, 1541816k used, 6767428k free, 343452k buffers
Swap: 2097128k total, 0k used, 2097128k free, 817160k cached
========================================================
在网上查了一些资料，不过至今也无法解决的问题就是（如1中的结果），程序占用内存非常小，可为什么SWAP却有1.1G？
