linux性能分析优化之基础指标参数(1) - Process Status | 进程状态

发表于 | 分类于
| 字数统计: 1k

查看方式

top命令

top命令中S那一列。即下图中SHR后面%CPU前面那一列。下图中的sshd进程和systemd进程的S列都处于S状态

1
2
3
4
5
6
7
8
9
10
11
12
13
14
$top

top - 22:49:54 up 2 days, 11:50,  2 users,  load average: 0.00, 0.00, 0.00
Tasks: 142 total,   1 running, 141 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  8043696 total,   174212 free,   105000 used,  7764484 buff/cache
KiB Swap:        0 total,        0 free,        0 used.  7574668 avail Mem

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
15460 ubuntu    20   0   93072   5216   4028 S   0.3  0.1   0:00.04 sshd
    1 root      20   0   37688   5212   3460 S   0.0  0.1   0:03.50 systemd
    .
    .
    .
ps命令

ps命令中STAT那一列。下图中systemd进程为Ss，[kthreadd]为S。

1
2
3
4
5
6
7
8
$ps aux

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0  37688  5212 ?        Ss   Apr24   0:03 /lib/systemd/systemd --system --deserialize 19
root         2  0.0  0.0      0     0 ?        S    Apr24   0:00 [kthreadd]
.
.
.

含义

top文档中的描述
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
3a. DESCRIPTIONS of Fields
      20. S  --  Process Status
          The status of the task which can be one of:

              D = uninterruptible sleep
              R = running
              S = sleeping
              T = stopped by job control signal
              t = stopped by debugger during trace
              Z = zombie


Tasks  shown  as  running should be more properly thought of as ready to run  --
   their task_struct is simply represented on the Linux run-queue.  Even without
a true SMP machine, you may see numerous tasks in this state depending on top's
delay interval and nice value.

A process in a runnable state is either using the CPU or waiting to use the CPU.
A process  in  uninterruptable  state  is  waiting for some I/O access, eg waiting for disk.
ps文档中的描述
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
PROCESS STATE CODES
       Here are the different values that the s, stat and state output specifiers
       (header "STAT" or "S") will display to describe the state of a process:

              D    uninterruptible sleep (usually IO)
              R    running or runnable (on run queue)
              S    interruptible sleep (waiting for an event to complete)
              T    stopped by job control signal
              t    stopped by debugger during the tracing
              W    paging (not valid since the 2.6.xx kernel)
              X    dead (should never be seen)
              Z    defunct ("zombie") process, terminated but not reaped by its parent

      For BSD formats and when the stat keyword is used, additional characters may be displayed:

              <    high-priority (not nice to other users)
              N    low-priority (nice to other users)
              L    has pages locked into memory (for real-time and custom IO)
              s    is a session leader
              l    is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)
              +    is in the foreground process group
资料

In linux, what do all the values in the “top” command mean? - Stack Overflow - answered by CesarB

‘S’ and ‘D’ are two sleep states, where the process is waiting for something to happen. The difference is that ‘S’ can be interrupted by a signal, while ‘D’ cannot (it is usually seen when the process is waiting for the disk).

‘T’ is a state where the process is stopped, usually via SIGSTOP or SIGTSTP. It can also be stopped by a debugger (ptrace). When you see that state, it usually is because you used Ctrl-Z to put a command on the background.

Linux进程状态解析 之 R、S、D、T、Z、X (主要有三个状态) - sdkdlwk的博客 - CSDN博客

Linux Process States - Stack Overflow - answered by zerodeux

S状态

大部分空闲时的进程都处于该状态。

D状态

linux - What is an uninterruptable process? - Stack Overflow - answered by CesarB

Uninterruptable processes are USUALLY waiting for I/O following a page fault.

Consider this:

  • The thread tries to access a page which is not in core (either an executable which is demand-loaded, a page of anonymous memory which has been swapped out, or a mmap()’d file which is demand loaded, which are much the same thing)
  • The kernel is now (trying to) load it in
  • The process can’t continue until the page is available.

The process/task cannot be interrupted in this state, because it can’t handle any signals; if it did, another page fault would happen and it would be back where it was.

When I say “process”, I really mean “task”, which under Linux (2.6) roughly translates to “thread” which may or may not have an individual “thread group” entry in /proc

In some cases, it may be waiting for a long time. A typical example of this would be where the executable or mmap’d file is on a network filesystem where the server has failed. If the I/O eventually succeeds, the task will continue. If it eventually fails, the task will generally get a SIGBUS or something.

D状态，为了保护进程数据与硬件状态一致，可看为是系统对进程和硬件设备的保护机制。正常情况下，D状态持续时间很短，一般可以忽略。如果出现大量D状态，需要关注是否io性能出现问题。

其他参考链接

本文完，作者yoko，尊重劳动人民成果，转载请注明原文出处： https://pengrl.com/p/21094/

0%