Hm, I wasn't following the kernel ml on this, but from the systemd's document it follows that there has to be _exactly one_ writer to this filesystem and this is a restriction forced by the kernel. systemd's decision is that it will be PID 1, not some other process. On non-systemd systems that can be some other root process, not necessarily PID 1, but only one.
-- Кирилл Елагин On Wed, Jun 4, 2014 at 11:53 AM, Michael Raskin <[email protected]> wrote: > >too bad :-) Thanks for the find! > > By the way, note that PID-1-only cgroups management is a systemd > decision, as far as I understand from the kernel mailing list posts, the > interface will still be a filesystem, and apparently it is OK to > implement cgroup management by multiple root processes (i.e. not > a migration to a single open socket). > > > > >On Wed, Jun 4, 2014 at 8:14 AM, Kirill Elagin <[email protected]> > wrote: > > > >> http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/ > >> > >> http://cgit.freedesktop.org/systemd/systemd/tree/src/core/main.c#n1469 > >> > >> > >> -- > >> Кирилл Елагин > >> > >> > >> On Wed, Jun 4, 2014 at 1:21 AM, Wout Mertens <[email protected]> > >> wrote: > >> > >>> On Tue, Jun 3, 2014 at 8:30 PM, Kirill Elagin <[email protected]> > >>> wrote: > >>> > >>>> Obviously systemd would then have to not do things that udev etc are > >>>>> already doing... Just running services, opening sockets, handling > cgroups... > >>>>> > >>>> > >>>> I doubt systemd can do this. > >>>> First of all, with the new kernel cgroups interface only PID 1 can > >>>> manage cgroups (on the kernel level). > >>>> Then, to properly handle services (i.e. processes) systemd has to be > PID > >>>> 1, right? Because otherwise it won't be able to track dead processes > and > >>>> all this stuff. > >>>> > >>> > >>> Are you sure about PID 1? I can't find that in > >>> https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt > >>> > >>> I'm thinking systemd can run in user-mode, even if it's running as > root. > >>> It's automatically turned on when it's not PID 1, I need to try it. > >>> > >>> Wout. > >>> > >> > >> > > > >--047d7b414174e5bf6404fafd5f90 > >Content-Type: text/html; charset=UTF-8 > >Content-Transfer-Encoding: 8bit > >X-MIME-Autoconverted: from quoted-printable to 8bit by 401a0bf1 id > mimedecode.py > > > ><div dir="ltr">too bad :-) Thanks for the find!</div><div > class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Jun 4, 2014 at > 8:14 AM, Kirill Elagin <span dir="ltr"><<a href="mailto: > [email protected]" target="_blank">[email protected]</a>></span> > wrote:<br> > ><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px > #ccc solid;padding-left:1ex"><div dir="ltr"><a href=" > http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/"; > target="_blank"> > http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/ > </a><br> > ><br><a href=" > http://cgit.freedesktop.org/systemd/systemd/tree/src/core/main.c#n1469"; > target="_blank"> > http://cgit.freedesktop.org/systemd/systemd/tree/src/core/main.c#n1469 > </a><br> > > > ></div><div class="gmail_extra"><br clear="all"><div><div > dir="ltr"><div><br></div>--<br>Кирилл Елагин</div></div><div><div > class="h5"> > ><br><br><div class="gmail_quote">On Wed, Jun 4, 2014 at 1:21 AM, Wout > Mertens <span dir="ltr"><<a href="mailto:[email protected]"; > target="_blank">[email protected]</a>></span> > wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 > .8ex;border-left:1px #ccc solid;padding-left:1ex"> > > > > > ><div dir="ltr"><div><div><div class="gmail_extra"><div > class="gmail_quote">On Tue, Jun 3, 2014 at 8:30 PM, Kirill Elagin <span > dir="ltr"><<a href="mailto:[email protected]"; target="_blank"> > [email protected]</a>></span> wrote:<br> > > > > > > > ><blockquote class="gmail_quote" style="margin:0px 0px 0px > 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div > dir="ltr"><div class="gmail_extra"><div><div class="gmail_quote"> > > > > > > > ><blockquote class="gmail_quote" style="margin:0px 0px 0px > 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div > dir="ltr"><div class="gmail_extra"><div class="gmail_quote"> > > > > > > > > > > > ><div class="gmail_extra">Obviously systemd would then have to not do > things that udev etc are already doing... Just running services, opening > sockets, handling > cgroups...</div></div></div></div></blockquote></div><br></div> > > > > > > > >I doubt systemd can do this.<br> > > > >First of all, with the new kernel cgroups interface only PID 1 can manage > cgroups (on the kernel level).<br>Then, to properly handle services (i.e. > processes) systemd has to be PID 1, right? Because otherwise it won't > be able to track dead processes and all this stuff.<br> > > > > > > > > > > > ></div></div> > ></blockquote></div><br></div></div></div><div class="gmail_extra">Are you > sure about PID 1? I can't find that in <a href=" > https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt"; > target="_blank"> > https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt</a></div> > > > > > > > ><div class="gmail_extra"><br></div><div class="gmail_extra">I'm > thinking systemd can run in user-mode, even if it's running as root. > It's automatically turned on when it's not PID 1, I need to try > it.</div> > > > > > ><span><font color="#888888"> > ><div class="gmail_extra"><br></div><div > class="gmail_extra">Wout.</div></font></span></div> > ></blockquote></div><br></div></div></div> > ></blockquote></div><br></div> > > > >--047d7b414174e5bf6404fafd5f90-- > > > >--===============1597797028== > >Content-Transfer-Encoding: 7bit > >Content-Disposition: inline > >MIME-Version: 1.0 > >Content-Type: text/plain; charset="utf-8" > >X-MIME-Autoconverted: from us-ascii to utf-8 by 401a0bf1 id mimedecode.py > > > >_______________________________________________ > >nix-dev mailing list > >[email protected] > >http://lists.science.uu.nl/mailman/listinfo/nix-dev > > > >--===============1597797028==-- > > > >
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