系统的系统
OS：archlinux
JDK：OpenJDK（IcedTea 2.4.3）（ArchLinux build 7.u45_2.4.3-1-x86_64）
我的java选项：
-Xms128m -Xmx512M -Xss1M -XX:MaxPermSize=50m
-XX:MaxDirectMemorySize=10M
-XX:ReservedCodeCacheSize=64m
-Dfile.encoding=UTF-8 -XX:NativeMemoryTracking=detai
Linux顶级命令显示，它使用6.8G * 19.5％= 1.326GB
Natvie内存跟踪显示它使用713MB
因此。哪一个是实际的物理内存使用量，如果它使用1.3GB内存， 额外的600 + MB物理内存在哪里去了？
最高输出
top - 09:20:37 up 48 min, 2 users, load average: 0.31, 0.33, 0.36
Tasks: 161 total, 1 running, 159 sleeping, 0 stopped, 1 zombie
%Cpu(s): 0.7 us, 0.3 sy, 0.0 ni, 99.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0
KiB Mem: 7091684 total, 4338428 used, 2753256 free, 117044 buffers
KiB Swap: 8388604 total, 0 used, 8388604 free, 1399904 cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5666 jilen 20 0 3553516 1.317g 22652 S 0.3 19.5 2:27.72 java
本机内存跟踪输出（jcmd VM.native_memory detail）
Native Memory Tracking:
Total: reserved=731125KB, committed=681117KB
- Java Heap (reserved=575488KB, committed=574976KB)
(mmap: reserved=575488KB, committed=574976KB)
- Class (reserved=6388KB, committed=6388KB)
(classes #6443)
(malloc=6388KB, #16725)
- Thread (reserved=27986KB, committed=27986KB)
(thread #27)
(stack: reserved=27756KB, committed=27756KB)
(malloc=82KB, #114)
(arena=148KB, #54)
- Code (reserved=70523KB, committed=21059KB)
(malloc=3963KB, #6149)
(mmap: reserved=66560KB, committed=17096KB)
- GC (reserved=26964KB, committed=26964KB)
(malloc=5900KB, #158)
(mmap: reserved=21064KB, committed=21064KB)
- Compiler (reserved=176KB, committed=176KB)
(malloc=78KB, #238)
(arena=98KB, #2)
- Internal (reserved=5463KB, committed=5431KB)
(malloc=5431KB, #1492)
(mmap: reserved=32KB, committed=0KB)
- Symbol (reserved=10668KB, committed=10668KB)
(malloc=9765KB, #77949)
(arena=903KB, #1)
- Memory Tracking (reserved=5616KB, committed=5616KB)
(malloc=5616KB, #120)
- Pooled Free Chunks (reserved=1854KB, committed=1854KB)
(malloc=1854KB)
Virtual memory map:
[0x00000000dce00000 - 0x0000000100000000] reserved 575488KB for Java Heap
from [JVM_handle_linux_signal+0x173dbd]
[0x00000000dce00000 - 0x00000000fff80000] committed 574976KB from [JVM_handle_linux_signal+0x650ab]
[0x00007f53801c7000 - 0x00007f53802c8000] reserved 1028KB for Thread Stack
from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53801c7000 - 0x00007f53802c8000] committed 1028KB from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f5381daf000 - 0x00007f5381eb0000] reserved 1028KB for Thread Stack
from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f5381daf000 - 0x00007f5381eb0000] committed 1028KB from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53821f0000 - 0x00007f53824f3000] reserved 3084KB for Thread Stack
from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53821f0000 - 0x00007f53824f3000] committed 3084KB from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f5382d49000 - 0x00007f5382e4a000] reserved 1028KB for Thread Stack
from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f5382d49000 - 0x00007f5382e4a000] committed 1028KB from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f538302a000 - 0x00007f538342e000] reserved 4112KB for Thread Stack
from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f538302a000 - 0x00007f538342e000] committed 4112KB from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53b47c7000 - 0x00007f53b4aca000] reserved 3084KB for Thread Stack
from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53b47c7000 - 0x00007f53b4aca000] committed 3084KB from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53b4db7000 - 0x00007f53b4eb8000] reserved 1028KB for Thread Stack
from [JVM_handle_linux_signal+0x127be9]
[0x00007f53b4db7000 - 0x00007f53b4eb8000] committed 1028KB from [JVM_handle_linux_signal+0x127be9]
[0x00007f53b4eb8000 - 0x00007f53b52bc000] reserved 4112KB for Thread Stack
from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53b4eb8000 - 0x00007f53b52bc000] committed 4112KB from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53b5894000 - 0x00007f53b5a96000] reserved 2056KB for Thread Stack
from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53b5894000 - 0x00007f53b5a96000] committed 2056KB from [JVM_handle_linux_signal+0x12f2ec]
[0x00007f53b5a96000 - 0x00007f53b5b97000] reserved 1028KB for Thread Stack
from [JVM_handle_linux_signal+0x17c90d]
[0x00007f53b5a96000 - 0x00007f53b5b97000] committed 1028KB from [JVM_handle_linux_signal+0x17c90d]
[0x00007f53b5b97000 - 0x00007f53b5c98000] reserved 1028KB for Thread Stack
from [JVM_FindSignal+0x118f1b]
[0x00007f53b5b97000 - 0x00007f53b5c98000] committed 1028KB from [JVM_FindSignal+0x118f1b]
[0x00007f53b6e70000 - 0x00007f53b8000000] reserved 17984KB for GC
from [JVM_handle_linux_signal+0x172529]
[0x00007f53b6e70000 - 0x00007f53b8000000] committed 17984KB from [JVM_handle_linux_signal+0x650ab]
[0x00007f53c4000000 - 0x00007f53c8000000] reserved 65536KB for Code
from [JVM_handle_linux_signal+0x1741a5]
[0x00007f53c4000000 - 0x00007f53c5070000] committed 16832KB from [JVM_handle_linux_signal+0x1746f4]
[0x00007f53cc0e4000 - 0x00007f53cc1fd000] reserved 1124KB for GC
from [JVM_handle_linux_signal+0x172529]
[0x00007f53cc0e4000 - 0x00007f53cc1fd000] committed 1124KB from [JVM_handle_linux_signal+0x650ab]
[0x00007f53cc1fd000 - 0x00007f53cc601000] reserved 4112KB for Thread Stack
from [AsyncGetCallTrace+0x3949c]
[0x00007f53cc1fd000 - 0x00007f53cc601000] committed 4112KB from [AsyncGetCallTrace+0x3949c]
[0x00007f53cc601000 - 0x00007f53cc71b000] reserved 1128KB for GC
from [JVM_handle_linux_signal+0x172529]
[0x00007f53cc601000 - 0x00007f53cc71b000] committed 1128KB from [dlerror+0x3aad37]
[0x00007f53cc71b000 - 0x00007f53cc81b000] reserved 1024KB for Code
from [JVM_handle_linux_signal+0x172289]
[0x00007f53cc71b000 - 0x00007f53cc75d000] committed 264KB from [JVM_handle_linux_signal+0x1746f4]
[0x00007f53cf497000 - 0x00007f53cf4a2000] reserved 44KB for GC
from [JVM_handle_linux_signal+0x172529]
[0x00007f53cf497000 - 0x00007f53cf54d000] committed 728KB from [JVM_handle_linux_signal+0x650ab]
[0x00007f53cf4a2000 - 0x00007f53cf54d000] reserved 684KB for GC
from [JVM_handle_linux_signal+0x172289]
[0x00007f53cf54d000 - 0x00007f53cf64e000] reserved 1028KB for Thread Stack
from [JVM_handle_linux_signal+0x12c997]
[0x00007f53cf54d000 - 0x00007f53cf64e000] committed 1028KB from [JVM_handle_linux_signal+0x12c997]
[0x00007f53cf656000 - 0x00007f53cf66f000] reserved 100KB for GC
from [JVM_handle_linux_signal+0x172289]
[0x00007f53cf656000 - 0x00007f53cf66f000] committed 100KB from [JVM_handle_linux_signal+0x650ab]
[0x00007f53cf66f000 - 0x00007f53cf677000] reserved 32KB for Internal
from [JVM_handle_linux_signal+0x3c924]
Details:
[0x00007f53ce330855] JVM_handle_linux_signal+0xee085
(malloc=6627KB #77628)
[0x00007f53ce291061] JVM_handle_linux_signal+0x4e891
(malloc=5120KB #5)
[0x00007f53ce293021] JVM_handle_linux_signal+0x50851
(malloc=5120KB #5)
[0x00007f53ce2a19b5] JVM_handle_linux_signal+0x5f1e5
(malloc=5120KB #5)
[0x00007f53ce1c8c64] JVM_FindSignal+0x1188f4
(malloc=4040KB #1)
[0x00007f53cde99851] dlerror+0x409851
(malloc=3903KB #5678)
[0x00007f53cdd2dcb3] dlerror+0x29dcb3
(malloc=2643KB #148)
[0x00007f53cdff5b86] AsyncGetCallTrace+0x6dc46
(malloc=2512KB #314)
[0x00007f53ce1c0b17] JVM_FindSignal+0x1107a7
(malloc=1274KB #106)
[0x00007f53ce291149] JVM_handle_linux_signal+0x4e979
(malloc=640KB #5)
[0x00007f53ce233375] JVM_FindSignal+0x183005
(malloc=524KB #419)
[0x00007f53ce38c670] JVM_handle_linux_signal+0x149ea0
(malloc=469KB #1)
[0x00007f53cde87c53] dlerror+0x3f7c53
(malloc=408KB #16085)
[0x00007f53cdd2d142] dlerror+0x29d142
(malloc=360KB #1)
[0x00007f53cdff5186] AsyncGetCallTrace+0x6d246
(malloc=310KB #25)
[0x00007f53ce38c581] JVM_handle_linux_signal+0x149db1
(malloc=156KB #1)
[0x00007f53cdd38523] dlerror+0x2a8523
(malloc=127KB #681)
[0x00007f53ce1c5acb] JVM_FindSignal+0x11575b
(malloc=96KB #2)
[0x00007f53ce1c807e] JVM_FindSignal+0x117d0e
(malloc=96KB #1)
[0x00007f53ce38e0e4] JVM_handle_linux_signal+0x14b914
(malloc=80KB #5)
[0x00007f53ce368abd] JVM_handle_linux_signal+0x1262ed
(malloc=71KB #25)
[0x00007f53ce1b4c27] JVM_FindSignal+0x1048b7
(malloc=64KB #16)
[0x00007f53ce1b4c97] JVM_FindSignal+0x104927
(malloc=64KB #16)
[0x00007f53ce25c867] JVM_handle_linux_signal+0x1a097
(malloc=55KB #116)
[0x00007f53ce1c0584] JVM_FindSignal+0x110214
(malloc=51KB #1)
[0x00007f53ce1c5a15] JVM_FindSignal+0x1156a5
(malloc=48KB #1)
[0x00007f53cdea0fc3] dlerror+0x410fc3
(malloc=37KB #464)
[0x00007f53cdf169bd] dlerror+0x4869bd
(malloc=36KB #13)
[0x00007f53ce3b2aa7] JVM_handle_linux_signal+0x1702d7
(malloc=24KB #13)
[0x00007f53cdff6496] AsyncGetCallTrace+0x6e556
(malloc=20KB #4)
[0x00007f53cdeb2ff3] dlerror+0x422ff3
(malloc=17KB #180)
[0x00007f53ce27ba1b] JVM_handle_linux_signal+0x3924b
(malloc=15KB #255)
[0x00007f53ce368b9d] JVM_handle_linux_signal+0x1263cd
(malloc=10KB #1)
[0x00007f53ce367fdb] JVM_handle_linux_signal+0x12580b
(malloc=8KB #47)
[0x00007f53cdff2df5] AsyncGetCallTrace+0x6aeb5
(malloc=8KB #11)
[0x00007f53cdf5d7d4] dlerror+0x4cd7d4
(malloc=8KB #1)
[0x00007f53ce289bc4] JVM_handle_linux_signal+0x473f4
(malloc=8KB #1)
[0x00007f53ce2059d6] JVM_FindSignal+0x155666
(malloc=7KB #62)
[0x00007f53ce27bb04] JVM_handle_linux_signal+0x39334
(malloc=7KB #251)
[0x00007f53ce242453] fork1+0x52b3
(malloc=6KB #28)
[0x00007f53ce024918] AsyncGetCallTrace+0x9c9d8
(malloc=5KB #18)
[0x00007f53cdd2d333] dlerror+0x29d333
(malloc=2KB #57)
[0x00007f53ce36a598] JVM_handle_linux_signal+0x127dc8
(malloc=2KB #1)
[0x00007f53ce2d6e24] JVM_handle_linux_signal+0x94654
(malloc=2KB #1)
[0x00007f53ce290d96] JVM_handle_linux_signal+0x4e5c6
(malloc=2KB #5)
[0x00007f53ce2a1536] JVM_handle_linux_signal+0x5ed66
(malloc=2KB #5)
[0x00007f53ce25a49b] JVM_handle_linux_signal+0x17ccb
(malloc=2KB #7)
[0x00007f53cde881eb] dlerror+0x3f81eb
(malloc=1KB #15)
[0x00007f53ce171720] JVM_FindSignal+0xc13b0
(malloc=1KB #74)
[0x00007f53cdf5ef54] dlerror+0x4cef54
(malloc=1KB #1)
[0x00007f53cde8a8aa] dlerror+0x3fa8aa
(malloc=1KB #59)
[0x00007f53ce3b658d] JVM_handle_linux_signal+0x173dbd
(mmap: reserved=575488KB, committed=574976KB)
[0x00007f53ce3b6975] JVM_handle_linux_signal+0x1741a5
(mmap: reserved=65536KB, committed=16832KB)
[0x00007f53ce3b4cf9] JVM_handle_linux_signal+0x172529
(mmap: reserved=20280KB, committed=20280KB)
[0x00007f53ce371abc] JVM_handle_linux_signal+0x12f2ec
(mmap: reserved=19532KB, committed=19532KB)
[0x00007f53cdfc13dc] AsyncGetCallTrace+0x3949c
(mmap: reserved=4112KB, committed=4112KB)
[0x00007f53ce3b4a59] JVM_handle_linux_signal+0x172289
(mmap: reserved=1808KB, committed=1048KB)
[0x00007f53ce1c928b] JVM_FindSignal+0x118f1b
(mmap: reserved=1028KB, committed=1028KB)
[0x00007f53ce36a3b9] JVM_handle_linux_signal+0x127be9
(mmap: reserved=1028KB, committed=1028KB)
[0x00007f53ce36f167] JVM_handle_linux_signal+0x12c997
(mmap: reserved=1028KB, committed=1028KB)
[0x00007f53ce3bf0dd] JVM_handle_linux_signal+0x17c90d
(mmap: reserved=1028KB, committed=1028KB)
[0x00007f53ce27f0f4] JVM_handle_linux_signal+0x3c924
(mmap: reserved=32KB, committed=0KB)
答案 0 :(得分：3)
RES或％MEM值是物理内存的实际使用情况。
由于您的系统根本没有内存压力，因此不会尝试恢复物理内存。这是因为这样的努力是一个失败的主张。如果内存不会很快被用于其他目的，那么浪费它就会使其免费。如果内存很快用于其他目的，那么使其自由的努力比浪费的更糟糕，它必须被撤消才能再次使用内存。当需要存储器时，现代操作系统直接将存储器从一个用户转移到另一个用户而不必使该存储器空闲。只有在没有其他选择时，内存才会被释放。
因此，基本上，物理内存暂时被浪费，直到系统可以找到更好的用途。如果您在耗费物理内存的计算机上运行其他任务，您将看到RES和％MEM值随着物理内存转换为另一种用途而下降。