Posted on 2007-01-30 11:19
acooly 閱讀(613)
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腳本語言
Linux中使用free可以查看系統內存使用狀態, 默認單位為k
blue_stone@blueice:~$ free
???????????? total?????? used?????? free???? shared??? buffers???? cached
Mem:?????? 2075320??? 1879172???? 196148????????? 0???? 533484???? 952588
-/+ buffers/cache:???? 393100??? 1682220
Swap:????? 2008084????????? 0??? 2008084
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Mem
行顯示了從系統角度看來內存使用的情況, total是系統可用的內存大小, 數量上等于系統物理內存減去內核保留的內存.
buffers和cached是系統用做緩沖的內存. buffers與某個塊設備關聯, 包含了文件系統元數據, 并且跟蹤了塊的變化.
cache只包含了文件本身.
-/+ buffers/cache行則從用戶角度顯示內存信息, 可用內存從數量上等于mem行used列值減去buffers和cached內存的大小. 因為buffers和cached是操作系統為加快系統運行而設置的, 當用戶需要時, 可以只接為用戶使用.
top和vmstat也顯示了系統內存的信息, 和free的顯示結果類似.
這些命令都是從/proc/meminfo中讀取內存信息.
blue_stone@blueice:~$ cat /proc/meminfo
MemTotal:????? 2075320 kB
MemFree:???????? 25016 kB
Buffers:??????? 763564 kB
Cached:???????? 879860 kB
SwapCached:????????? 0 kB
Active:??????? 1056968 kB
Inactive:?????? 843136 kB
HighTotal:????? 917440 kB
HighFree:??????? 13892 kB
LowTotal:????? 1157880 kB
LowFree:???????? 11124 kB
SwapTotal:???? 2008084 kB
SwapFree:????? 2008084 kB
Dirty:??????????? 4708 kB
Writeback:?????????? 0 kB
Mapped:???????? 707152 kB
Slab:?????????? 102728 kB
CommitLimit:?? 3045744 kB
Committed_AS:?? 691808 kB
PageTables:?????? 2936 kB
VmallocTotal:?? 114680 kB
VmallocUsed:???? 14800 kB
VmallocChunk:??? 98800 kB
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關于/proc/meminfo中各行的含意, 在內核源代碼的Documentation/filesystems/proc.txt文件中有敘述
系統的真實內存大小可以用dmesg |grep [mM][eE][mM]看到
blue_stone@blueice:~$ dmesg |grep [mM][eE][mM]
895MB HIGHMEM available.
1152MB LOWMEM available.
? HighMem zone: 229360 pages, LIFO batch:31
Memory: 2073292k/2097088k available (1493k kernel code, 21648k reserved, 546k data, 196k init, 917440k highmem)
Freeing initrd memory: 1079k freed
? MEM window: f8000000-f80fffff
highmem bounce pool size: 64 pages
Freeing unused kernel memory: 196k freed
ehci_hcd 0000:00:10.4: irq 177, io mem 0xf8121000
/dev/vmnet: hub 0 does not exist, allocating memory.
[fglrx] Maximum main memory to use for locked dma buffers: 1898 MBytes.
/dev/vmnet: hub 3 does not exist, allocating memory.
/dev/vmnet: hub 1 does not exist, allocating memory.
/dev/vmnet: hub 2 does not exist, allocating memory.
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進程使用的內存可以用top, ps來查看top中有3個列 VIRT? RES? SHR, 標示了進程使用的內存情況, VIRT標識這個進程可以使用的內存總大小, 包括這個進程真實使用的內存, 映射過的文件,? 和別的進程共享的內存等.
RES標識這個這個進程真實占用內存的大小.
SHR標識可以和別的進程共享的內存和庫大小.
/proc/pid/status顯示一個進程的詳細狀態, 下面是一個示例:
blue_stone@blueice:~$ cat /proc/5346/status
Name:?? bash
State:? S (sleeping)
SleepAVG:?????? 98%
Tgid:?? 5346
Pid:??? 5346
PPid:?? 5343
TracerPid:????? 0
Uid:??? 1000??? 1000??? 1000??? 1000
Gid:??? 104???? 104???? 104???? 104
FDSize: 256
Groups: 6 24 29 44 104 113 1000 1001
VmPeak:???? 6528 kB
VmSize:???? 6528 kB
VmLck:???????? 0 kB
VmHWM:????? 1976 kB
VmRSS:????? 1976 kB
VmData:????? 752 kB
VmStk:??????? 84 kB
VmExe:?????? 644 kB
VmLib:????? 1788 kB
VmPTE:??????? 16 kB
Threads:??????? 1
SigQ:?? 0/4294967295
SigPnd: 0000000000000000
ShdPnd: 0000000000000000
SigBlk: 0000000000000000
SigIgn: 0000000000384004
SigCgt: 000000004b813efb
CapInh: 0000000000000000
CapPrm: 0000000000000000
CapEff: 0000000000000000
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VmSize即為該進程內存總大小, 和top輸出中的VIRT一致.
轉至:http://www.cublog.cn/u/7667/showart_172007.html