Linux memory

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  1. get top memory process

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    # +3[CPU]
    ps aux|head -1;ps aux|grep -v PID|sort -rn -k +4|head

  2. free

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    free -m
    free -b -s5
    free -h

                  total       used       free     shared    buffers     cached
    Mem:          7.7G       7.6G       133M       164K       190M       3.1G
    -/+ buffers/cache:       4.2G       3.5G
    Swap:           0B         0B         0B

from the point of view of OS buffers and cached memory is used
available memory size = free + buffers + cached

  1. ps
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    ps aux --sort -rss
    ps aux | grep xxx
  • USER process’ user
  • PID process id
  • %CPU cpu proportion
  • %MEM memory proportion
  • VSZ total VM size in kB
  • RSS resident set size
  • TTY terminal
  • STAT
    • R Running or runnable (on run queue)
    • S Interruptible sleep (waiting for an event to complete)
  • START time the command started
  • TIME run cpu time
  • COMMAND string as arguments
  1. /proc
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    cat /proc/pid/status

    VmPeak:	 5033936 kB
    VmSize:	 5033620 kB
    VmLck:	       0 kB
    VmHWM:	 1151928 kB
    VmRSS:	 1151644 kB
    VmData:	 4875980 kB
    VmStk:	      88 kB
    VmExe:	      36 kB
    VmLib:	  127412 kB
    VmPTE:	    2724 kB
    VmSwap:	       0 kB
    Threads:	72
  • VmSize(KB) task’s virtual address space size (total_vm-reserved_vm)
  • VmLck(KB) been locked physical memory size, can’t exchange to hard drive(locked_vm)
  • VmRSS(KB) resident set size, physical memory. (rss in ps)
  • VmData(KB) program’s data paragraph size (virtual), store initialized data(total_vm-shared_vm-stack_vm)
  • VmStk(KB) task’s stack size in user(stack_vm)
  • VmExe(KB) executable virtual memory size, (exclude lib) (end_code-start_code)
  • VmLib(KB) lib mapping to task memory space size(exec_lib)
  • VmPTE(KB) this process’s page size
  • Threads share this signal’s task number(POSIX multi app, thread group use same signal)
  1. top
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    # [shit+m sort by memory]
    top -p 6506

    top - 11:14:20 up 125 days,  1:47,  1 user,  load average: 0.00, 0.00, 0.00
    Tasks:   1 total,   0 running,   1 sleeping,   0 stopped,   0 zombie
    Cpu(s):  0.2%us,  0.1%sy,  0.0%ni, 99.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
    Mem:   8061396k total,  7925220k used,   136176k free,   194748k buffers
    Swap:        0k total,        0k used,        0k free,  3291676k cached

      PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND  
     3825 root      20   0  164m  41m 1020 S  0.0  0.5 146:54.42 redis-server

Cpu(s): 0.2%us, 0.1%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

  • us user space cup proportion
  • sy system core space cup proportion
  • ni priority changed task cup proportion
  • id idle cpu proportion
  • wa waiting IO cpu proportion
  • hi hard ware cost
  • si soft ware cost
  • st steal time

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

  • PR priority rank
  • NI nice value
  • VIRT virtual memory size
  • RES not be exchanged memory size
  • SHR share meory size