在服务器中48GB的内存，当我跑步时top，我看到不到 500 MB免费（1%），而当我对 % 列求和时已使用内存每个过程大约30％。
由于只有2.7％的交换内存被使用后，我可以安全地运行更多进程，以从系统中回收已分配但未使用的内存吗？
（我想确定一下，因为我不是唯一使用该服务器的人）
$ top
top - 13:49:07 up 100 days, 5:56, 2 users, load average: 19.17, 19.27, 19.31
Tasks: 712 total, 4 running, 708 sleeping, 0 stopped, 0 zombie
Cpu(s): 39.8%us, 0.1%sy, 0.0%ni, 60.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 65978420k total, 65511044k used, 467376k free, 2123640k buffers
Swap: 32767976k total, 885828k used, 31882148k free, 44048824k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2790 user1 25 0 4336m 3.9g 9992 R 100.0 6.2 171:14.27 python26
2785 user1 25 0 4257m 3.8g 9992 R 100.0 6.1 171:23.51 python26
2803 user1 25 0 4058m 3.6g 9992 R 100.0 5.8 171:05.19 python26
22269 root 18 0 1378m 348m 51m S 100.1 0.5 858:21.01 MATLAB
19745 root 18 0 1369m 344m 51m S 99.7 0.5 849:19.47 MATLAB
22901 root 18 0 1353m 339m 49m S 99.7 0.5 838:21.33 MATLAB
22511 root 18 0 1348m 322m 49m S 100.1 0.5 849:47.15 MATLAB
19517 root 18 0 1262m 318m 51m S 99.7 0.5 853:36.01 MATLAB
19295 root 18 0 1283m 314m 51m S 100.1 0.5 867:38.72 MATLAB
23042 root 18 0 1274m 306m 51m S 99.7 0.5 827:33.94 MATLAB
10289 root 18 0 1141m 305m 4764 S 0.3 0.5 2514:51 java
20767 root 18 0 1265m 303m 51m S 99.7 0.5 797:40.98 MATLAB
20382 root 18 0 1268m 302m 51m S 100.1 0.5 809:05.64 MATLAB
21956 root 18 0 1261m 298m 51m S 100.1 0.5 867:56.52 MATLAB
22743 root 18 0 1268m 287m 51m S 100.1 0.4 837:39.99 MATLAB
20180 root 18 0 1253m 280m 51m S 100.1 0.4 826:00.43 MATLAB
23526 root 18 0 1243m 271m 51m S 100.1 0.4 810:12.43 MATLAB
24176 root 18 0 1205m 240m 51m S 100.1 0.4 787:07.32 MATLAB
19060 root 19 0 1179m 233m 51m S 100.1 0.4 883:03.83 MATLAB
12401 root 20 0 16.3g 218m 4256 S 0.0 0.3 176:20.91 java
23825 root 18 0 1144m 205m 51m S 100.1 0.3 798:55.61 MATLAB
10210 root 34 19 381m 142m 1436 S 0.0 0.2 1:24.52 yum-updatesd
20569 root 19 0 16.3g 89m 16m S 5.3 0.1 648:46.29 java
23937 root 18 0 16.4g 85m 16m S 0.0 0.1 934:03.86 java
20438 root 19 0 16.3g 84m 16m S 0.0 0.1 638:23.89 java
20487 root 19 0 16.4g 82m 16m S 0.0 0.1 644:32.01 java
11877 root 17 0 16.4g 50m 5692 S 0.0 0.1 1491:55 java
10223 root 19 0 16.4g 50m 5180 S 0.0 0.1 1239:56 java