Re: file born 30 seconds after its creation on ext4 - bug?

From	Vincent Lefevre <vincent@vinc17.net>
Newsgroups	linux.debian.user
Subject	Re: file born 30 seconds after its creation on ext4 - bug?
Date	2022-04-27 04:50 +0200
Message-ID	<EgFUB-bs7c-1@gated-at.bofh.it> (permalink)
References	<EgtJL-bkEH-11@gated-at.bofh.it> <Egxkm-bmT9-3@gated-at.bofh.it> <Egxu1-bmWn-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 2022-04-26 12:47:53 -0500, Nicholas Geovanis wrote:
> On Tue, Apr 26, 2022 at 12:37 PM Nicholas Geovanis <nickgeovanis@gmail.com>
> wrote:
> 
> > On Tue, Apr 26, 2022 at 8:45 AM Vincent Lefevre <vincent@vinc17.net>
> > wrote:
> >
> >> On an ext4 filesystem, I got a file born 30 seconds after its
> >> actual creation. Is this a bug?
> >>
> >
> > Only experimentation can really back me up on this, but consider the
> > following:
> >
> > Every time you use the "|" operator or the ";" separator on a command-line,
> > new processes are being spawned. Which wait to be dispatched on a core.
> > But you are not serializing the dispatch of those processes, and
> > especially with
> > 16 fast cores, you can't predict their order of execution.
> >
> 
> A couple more observations:
> (1) It looks like you're trying to observe behavior in the very same
> filesystem in which
> the running executable is loaded from and its log files are being
> written-to. That's
> alot of variables in motion at once.
> 
> (2) Yes, the "|" is in a sense serializing I/O in "lt|head". But the
> filesystem is syncing
> buffered and disk-based content separately from that.

There are no parallel writes to the file, i.e. everything is
serialized from this point of view.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)

Thread

file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-26 15:50 +0200
  Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-26 19:10 +0200
    Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 04:40 +0200
      Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-27 09:10 +0200
        Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 10:30 +0200
          Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-27 11:40 +0200
            Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 15:20 +0200
              Re: file born 30 seconds after its creation on ext4 - bug? Greg Wooledge <greg@wooledge.org> - 2022-04-27 15:30 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 16:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Stefan Monnier <monnier@iro.umontreal.ca> - 2022-04-28 04:50 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Greg Wooledge <greg@wooledge.org> - 2022-04-28 05:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? duh <fill_in_the_blanks@email.com> - 2022-04-29 16:20 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Marc Auslander <marcausl@gmail.com> - 2022-04-29 20:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? "sp007@caiway.net" <sp007@caiway.net> - 2022-04-29 22:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-04-30 07:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-30 10:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-04-30 14:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-05-02 01:20 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-05-02 07:30 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Curt <curty@free.fr> - 2022-04-30 14:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-04-30 15:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-30 15:20 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-05-02 01:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Greg Wooledge <greg@wooledge.org> - 2022-05-02 01:40 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? David Wright <deblis@lionunicorn.co.uk> - 2022-05-02 17:10 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? <tomas@tuxteam.de> - 2022-05-02 18:20 +0200
                Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-28 10:40 +0200
            Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-28 11:40 +0200
  Re: file born 30 seconds after its creation on ext4 - bug? Nicholas Geovanis <nickgeovanis@gmail.com> - 2022-04-26 19:40 +0200
    Re: file born 30 seconds after its creation on ext4 - bug? Nicholas Geovanis <nickgeovanis@gmail.com> - 2022-04-26 19:50 +0200
      Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 04:50 +0200
  Re: file born 30 seconds after its creation on ext4 - bug? Stefan Monnier <monnier@iro.umontreal.ca> - 2022-04-26 20:20 +0200
    Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-27 05:10 +0200
  Re: file born 30 seconds after its creation on ext4 - bug? "Thomas Schmitt" <scdbackup@gmx.net> - 2022-04-28 11:30 +0200
    Re: file born 30 seconds after its creation on ext4 - bug? Vincent Lefevre <vincent@vinc17.net> - 2022-04-28 12:20 +0200

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