Memory usage and processor resources for a specific process

from the documentation :

 Table 1-1: Process specific entries in /proc .............................................................................. File Content clear_refs Clears page referenced bits shown in smaps output cmdline Command line arguments cpu Current and last cpu in which it was executed (2.4)(smp) cwd Link to the current working directory environ Values of environment variables exe Link to the executable of this process fd Directory, which contains all file descriptors maps Memory maps to executables and library files (2.4) mem Memory held by this process root Link to the root directory of this process stat Process status statm Process memory status information status Process status in human readable form wchan Present with CONFIG_KALLSYMS=y: it shows the kernel function symbol the task is blocked in - or "0" if not blocked. pagemap Page table stack Report full stack trace, enable via CONFIG_STACKTRACE smaps a extension based on maps, showing the memory consumption of each mapping and flags associated with it numa_maps an extension based on maps, showing the memory locality and binding policy as well as mem usage (in pages) of each mapping. 

for example, to get “status” information about the process, all you need is to read the /proc/идентификатор-процесса/status file:

 $ cat /proc/self/status Name: cat State: R (running) Tgid: 5452 Pid: 5452 PPid: 743 TracerPid: 0 (2.4) Uid: 501 501 501 501 Gid: 100 100 100 100 FDSize: 256 Groups: 100 14 16 VmPeak: 5004 kB VmSize: 5004 kB VmLck: 0 kB VmHWM: 476 kB VmRSS: 476 kB RssAnon: 352 kB RssFile: 120 kB RssShmem: 4 kB VmData: 156 kB VmStk: 88 kB VmExe: 68 kB VmLib: 1412 kB VmPTE: 20 kb VmSwap: 0 kB HugetlbPages: 0 kB Threads: 1 SigQ: 0/28578 SigPnd: 0000000000000000 ShdPnd: 0000000000000000 SigBlk: 0000000000000000 SigIgn: 0000000000000000 SigCgt: 0000000000000000 CapInh: 00000000fffffeff CapPrm: 0000000000000000 CapEff: 0000000000000000 CapBnd: ffffffffffffffff Seccomp: 0 voluntary_ctxt_switches: 0 nonvoluntary_ctxt_switches: 1 

lines in which designate:

 Table 1-2: Contents of the status files (as of 4.1) .............................................................................. Field Content Name filename of the executable State state (R is running, S is sleeping, D is sleeping in an uninterruptible wait, Z is zombie, T is traced or stopped) Tgid thread group ID Ngid NUMA group ID (0 if none) Pid process id PPid process id of the parent process TracerPid PID of process tracing this process (0 if not) Uid Real, effective, saved set, and file system UIDs Gid Real, effective, saved set, and file system GIDs FDSize number of file descriptor slots currently allocated Groups supplementary group list NStgid descendant namespace thread group ID hierarchy NSpid descendant namespace process ID hierarchy NSpgid descendant namespace process group ID hierarchy NSsid descendant namespace session ID hierarchy VmPeak peak virtual memory size VmSize total program size VmLck locked memory size VmHWM peak resident set size ("high water mark") VmRSS size of memory portions. It contains the three following parts (VmRSS = RssAnon + RssFile + RssShmem) RssAnon size of resident anonymous memory RssFile size of resident file mappings RssShmem size of resident shmem memory (includes SysV shm, mapping of tmpfs and shared anonymous mappings) VmData size of private data segments VmStk size of stack segments VmExe size of text segment VmLib size of shared library code VmPTE size of page table entries VmPMD size of second level page tables VmSwap amount of swap used by anonymous private data (shmem swap usage is not included) HugetlbPages size of hugetlb memory portions Threads number of threads SigQ number of signals queued/max. number for queue SigPnd bitmap of pending signals for the thread ShdPnd bitmap of shared pending signals for the process SigBlk bitmap of blocked signals SigIgn bitmap of ignored signals SigCgt bitmap of caught signals CapInh bitmap of inheritable capabilities CapPrm bitmap of permitted capabilities CapEff bitmap of effective capabilities CapBnd bitmap of capabilities bounding set Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...) Cpus_allowed mask of CPUs on which this process may run Cpus_allowed_list Same as previous, but in "list format" Mems_allowed mask of memory nodes allowed to this process Mems_allowed_list Same as previous, but in "list format" voluntary_ctxt_switches number of voluntary context switches nonvoluntary_ctxt_switches number of non voluntary context switches 

The description of the contents of another relevant file is /proc/идентификатор-процесса/stat :

 Table 1-4: Contents of the stat files (as of 2.6.30-rc7) .............................................................................. Field Content pid process id tcomm filename of the executable state state (R is running, S is sleeping, D is sleeping in an uninterruptible wait, Z is zombie, T is traced or stopped) ppid process id of the parent process pgrp pgrp of the process sid session id tty_nr tty the process uses tty_pgrp pgrp of the tty flags task flags min_flt number of minor faults cmin_flt number of minor faults with child's maj_flt number of major faults cmaj_flt number of major faults with child's utime user mode jiffies stime kernel mode jiffies cutime user mode jiffies with child's cstime kernel mode jiffies with child's priority priority level nice nice level num_threads number of threads it_real_value (obsolete, always 0) start_time time the process started after system boot vsize virtual memory size rss resident set memory size rsslim current limit in bytes on the rss start_code address above which program text can run end_code address below which program text can run start_stack address of the start of the main process stack esp current value of ESP eip current value of EIP pending bitmap of pending signals blocked bitmap of blocked signals sigign bitmap of ignored signals sigcatch bitmap of caught signals 0 (place holder, used to be the wchan address, use /proc/PID/wchan instead) 0 (place holder) 0 (place holder) exit_signal signal to send to parent thread on exit task_cpu which CPU the task is scheduled on rt_priority realtime priority policy scheduling policy (man sched_setscheduler) blkio_ticks time spent waiting for block IO gtime guest time of the task in jiffies cgtime guest time of the task children in jiffies start_data address above which program data+bss is placed end_data address below which program data+bss is placed start_brk address above which program heap can be expanded with brk() arg_start address above which program command line is placed arg_end address below which program command line is placed env_start address above which program environment is placed env_end address below which program environment is placed exit_code the thread's exit_code in the form reported by the waitpid system call 

regarding what kind of information from the /proc pseudo-file system is read by programs like ps , and how it is interpreted, one should refer to the source texts of these specific programs.

additional Information: $ man 5 proc