Display various information of memory
●Information about memory
To get information about memory, refer to the /proc/meminfo file.
This file is used as the memory information displayed by the top, free, and vmstat commands.
| root@Lion:~# cat /proc/meminfo MemTotal: 3977756 kB MemFree: 468544 kB MemAvailable: 1805372 kB Buffers: 85952 kB Cached: 1443148 kB SwapCached: 0 kB Active: 2671120 kB Inactive: 579952 kB Active(anon): 1766784 kB Inactive(anon): 17020 kB Active(file): 904336 kB Inactive(file): 562932 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 0 kB Writeback: 0 kB AnonPages: 1717284 kB Mapped: 78440 kB Shmem: 61812 kB Slab: 189912 kB SReclaimable: 144328 kB SUnreclaim: 45584 kB KernelStack: 2496 kB PageTables: 7136 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 1988876 kB Committed_AS: 2286236 kB VmallocTotal: 34359738367 kB VmallocUsed: 0 kB VmallocChunk: 0 kB Percpu: 1920 kB HardwareCorrupted: 0 kB AnonHugePages: 1603584 kB ShmemHugePages: 0 kB ShmemPmdMapped: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 0 kB DirectMap4k: 133124 kB DirectMap2M: 3997696 kB |
●Check memory usage.
To check the memory usage, use the free command.
When executed without options or with the -k option, the display will be in kilobytes; when executed with the -d option, it will be in bytes; and when executed with the -m option, it will be in megabytes.
| root@Lion:~# free total used free shared buffers cached Mem: 1035140 544736 490404 0 47868 401036 -/+ buffers/cache: 95832 939308 Swap: 2097144 0 209714 |
Items displayed by the free command
total：Total memory capacity
used：Memory capacity in use
free：free memory space
shared：shared memory capacity
buffers：Disk buffer space used by the kernel
cached：Cache memory capacity
●Update and display memory usage at regular intervals.
If you need to monitor memory usage continuously, such as when you run a process that consumes a large amount of memory, you can update the memory usage status at regular intervals and display it.
To do this, add the option "-s" to the free command and specify the update time as an argument.
| root@Lion:~# free -s5 total used free shared buffers cached Mem: 1035140 385080 650060 0 24856 286260 -/+ buffers/cache: 73964 961176 Swap: 2097144 0 2097144 ↓Five seconds elapsed. total used free shared buffers cached Mem: 1035140 385080 650060 0 24856 286268 -/+ buffers/cache: 73956 961184 Swap: 2097144 0 2097144 ↓Five seconds elapsed. total used free shared buffers cachedMem: 1035140 385080 650060 0 24864 286260 -/+ buffers/cache: 73956 961184 Swap: 2097144 0 2097144 |