Memory Issue

top command


# top
up  1:09, 3 user,  load average: 0.36, 0.12, 0.11
Tasks:   228 total,   1 running, 227 sleeping,   0 stopped,   0 zombie
Cpu(s):  3.7% us,  1.9 sy,  1.2 ni, 91.8 id,  1.3 wa,  0.0 hi,  0.1 si,  0.0 st
Memory(MB):  32092 total,   321 free,   31483 used,   287 buff/cache
Swap(MB):   1024 total,  0.0 free,   1024 used.      200 avail Mem

//All processes Running on System
pid   user    pr(priority)  ni(nice) virt  res  shr(SharedMem) State  %cpu %mem   time    command
7801  root    20               0    59.6g  26.5g   3224        R       15   84.2  4:36.47  sssd
Show output Sorted by Processes that uses CPU most.
up: System up time, Logged in users, CPU load Average(1/5/15 min)[SIMILAR to uptime command]
CPU(s): us(CPU used by User processes), sy(System processes)
Memory(KB): Utilization Status. 2029876=Total system mem. [SIMILAR to free command]
VIRT(Virtual Memory): RAM(RES)+SWAP(Paged out to disk)+Shared_libs
High VIRT is not problem, process reserved lot of address space for itself.
RES(Resident Memory): sssd using 26.5GB Out of 32GB of RAM

htop command


# htop //Similar to top with more colourful, more graphic interface which gives you more control of display scrolling
# ps    //Reports snapshot of current processes.        //ps -aux    a:Displays all processes on a terminal.  u: Show user-name,  x; Lists all process(Including background processes)
    user  pid  %cpu %mem  vsz     rss  tty  state   start-time      command
    root    1    0.0       0.1    19404  832  ?     Ss   Mar02 0:01   /sbin/init
    root    2    78.0       0.0       0         0    ?     S    Mar02 0:00   [abc]
    root    3    0.0       0.0       0         0    ?     S    Mar02 0:00   [migration/0]
    States of process:  D(uninterruptible sleep),  R(Running), S(Interruptible sleep),  T(stopped by job control signal),  t(stopped by debugger during the tracing), X(dead), Z(defunct/Zombie process, terminated but not reaped by its parent)

df command


# df -h        //Disk Free, Shows local and network file system
Filesystem   Size     Used    Avail    Use%  Mounted on
/dev/map/root 11G    3.8G     6.0G     39%    /          // root file system mounted on "/" has only 6.0G available
devtmpfs     2.0G       0     2.0G      0%    /dev
tmpfs        2.0G       0     2.0G      0%    /dev/shm
tmpfs        2.0G    1.6M     2.0G      1%    /run
tmpfs        2.0G       0     2.0G      0%    /tmp
file system Description
/dev/sdd Real physical block device(Hard Disk). Mounted on root filesystem (/)
tmpfs temporary file system that resides on volatile memory(RAM). Data is lost when system reboots. Includes /run etc
tmpfs temporary file system that resides on volatile memory(RAM). Data is lost when system reboots. Includes /run etc
shm (shared memory) tmpfs mounts for shared memory only.

atop output

Commands:
Open existing file using `atop -r file_name`
  Press M for memory view, C for CPU view
  s for scheduling activity
  t for next sample taken after 10 min 


atop
MEM | tot 32G | free 860.4M | cache 6.3G    // 6.3G still left to be used
SWP | tot 1G | free 590M | swcac 16.3M

Press C
PID       VGROW       RGROW       CPU       CMD
xx         45.0G      17.8G       30%       npraxy

Press M
PID       VDATA       VSIZE       RSIZE    VGROW   RGROW     SWAPZ    MEM    CMD
xx         44.3G      45.0G       17.8G    45.05G  17.8G     92.4M    57%   npraxy
VSIZE(Virtual Size): total amount of virtual memory currently reserved by the process.
VDATA: size of private process memory (heap and data sections) that is not shared and is part of the virtual address space
SWAPZ: size of the swap space currently used by a process
VGROW (Virtual Memory Growth): amount by which a process’s virtual memory size (VSIZE) has increased ("grown") during the monitoring interval.
RGROW: Increase ("growth") in the resident memory of process. How much additional RAM process has used since last monitoring time
RSIZE (Resident Size):Total resident memory used by a process, Resident memory is the portion of a process's memory that is actually held in physical RAM
PSIZE(Physical Size): physical memory size occupied by the process
swcac(Swap Cache): Cache which is holding the pages.