1. Forum
  2. FidoNet
  3. ALT.OS.LINUX.MAGEIA

  • [OT] PIDs.

    From Doug Laidlaw@2:250/1 to All on Thu Jul 7 15:18:32 2022
    Just Curious:
    When I started with Linux (when the whole kernel would still fit on a
    3.5 inch floppy), there was only one series of PIDs; now there seem to
    be several, running concurrently. Early in the session. PID numbers are greater than they used to be.

    Is there a reason for this?

    Doug.

    --- MBSE BBS v1.0.8 (Linux-x86_64)
    * Origin: Aioe.org NNTP Server (2:250/1@fidonet)
  • From David W. Hodgins@2:250/1 to All on Thu Jul 7 22:00:39 2022
    On Thu, 07 Jul 2022 10:18:32 -0400, Doug Laidlaw <[email protected]> wrote:

    Just Curious:
    When I started with Linux (when the whole kernel would still fit on a
    3.5 inch floppy), there was only one series of PIDs; now there seem to
    be several, running concurrently. Early in the session. PID numbers are greater than they used to be.

    Is there a reason for this?

    1. Multi threaded programming for better utilization for multiple cores with each thread being given it's own pid.
    2. Making programs better at continuing to work even if some parts crash by using multiple processes.

    Run htop as root. Change it to sort by pid. Press K to toggle the showing of kernel threads on (press K again to toggle it off). Each thread is assigned a pid. In the case of the kernel on my system, the last kernel pid is 562. Not all of the threads are still running, so there are gaps in the numbers.

    Similarly use H to toggle user thread displays on or off.

    Some programs use multiple processes so that one failing doesn't stop the whole program (eg. firefox). One tab crashing doesn't kill the entire browser.

    Regards, Dave Hodgins

    --- MBSE BBS v1.0.8 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Bobbie Sellers@2:250/1 to All on Thu Jul 7 23:07:29 2022
    On 7/7/22 07:18, Doug Laidlaw wrote:
    Just Curious:
    When I started with Linux (when the whole kernel would still fit on a
    3.5 inch floppy), there was only one series of PIDs; now there seem to
    be several, running concurrently.  Early in the session. PID numbers are greater than they used to be.

    Is there a reason for this?

    Doug.

    The kernel is full of drivers for various hardwares, new features for the more complex functions required for day to day
    computing. That the kernel is full of drivers is a problem for
    me but the alternative would make Linux less able to compete. The
    HURD kernel is not viable yet.

    I suggest you look up Kernel News using DuckDuckGo.


    bliss - brought to you by the power and ease of PCLinuxOS,
    the Perfect Computer Linux Operating System(for me),
    A Rolling Release, Rocking kernel 5.18.9!
    and a minor case of hypergraphia.

    --
    bliss dash SF 4 ever at dslextreme dot com



    --- MBSE BBS v1.0.8 (Linux-x86_64)
    * Origin: dis-organization (2:250/1@fidonet)
  • From Aragorn@2:250/1 to All on Thu Jul 7 23:57:40 2022
    On 07.07.2022 at 17:00, David W. Hodgins scribbled:

    On Thu, 07 Jul 2022 10:18:32 -0400, Doug Laidlaw
    <[email protected]> wrote:

    Just Curious:
    When I started with Linux (when the whole kernel would still fit on
    a 3.5 inch floppy), there was only one series of PIDs; now there
    seem to be several, running concurrently. Early in the session.
    PID numbers are greater than they used to be.

    Is there a reason for this?

    1. Multi threaded programming for better utilization for multiple
    cores with each thread being given it's own pid. [...]

    More precisely, GNU/Linux uses the native POSIX thread model, in which
    threads appear as individual processes, each with their own PID.

    Back in the days Doug is talking about, Linux threads were not
    enumerated with PIDs yet, because the native POSIX thread model had not
    yet been adopted into the kernel and into glibc. The default was a
    different threading model with threads having the PID of the parent
    process, and the switch to native POSIX threads happened gradually and distribution-dependent, around 2004-2005.

    --
    With respect,
    = Aragorn =


    --- MBSE BBS v1.0.8 (Linux-x86_64)
    * Origin: A noiseless patient Strider (2:250/1@fidonet)
  • From Bit Twister@2:250/1 to All on Fri Jul 8 00:08:35 2022
    On Fri, 8 Jul 2022 00:18:32 +1000, Doug Laidlaw wrote:
    Just Curious:
    When I started with Linux (when the whole kernel would still fit on a
    3.5 inch floppy), there was only one series of PIDs; now there seem to
    be several, running concurrently. Early in the session. PID numbers are greater than they used to be.

    Is there a reason for this?

    Every program/process gets a new pid. System keeps track of last pid used,
    My system goes through all pids in about 24 hours. It is up 24/7.

    As you can see current pid is kinda high at the time of this reply.
    # ps aux | grep -Eie kernel
    root 1547313 0.0 0.0 9128 772 pts/7 S+ 17:54 0:00 grep -Eie kernel

    --- MBSE BBS v1.0.8 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)