Re: [gentoo-user] Cannot shutdown or reboot because of logind disconnection

[Michael]

On Saturday, 17 September 2022 12:11:56 BST tastytea wrote:
> On 2022-09-17 17:37+0800 johnstrass  <johnstrass@×××.com> wrote:
> > At 2022-09-17 14:15:51, "Walter Dnes" <waltdnes@××××××××.org> wrote:
> > >On Sat, Sep 17, 2022 at 10:40:53AM +0800, johnstrass wrote
> > >
> > >> Compiling gcc uses alot of memory, sometimes only less then 10MB
> > >> left free ( I am doing this on a small yeeloong netbook with only
> > >> 1GB memory).
> > >>
> > >  Ouch, I'm surprised it compiles at all.  The Gentoo install
> > >
> > > handbook
> > >
> > >https://wiki.gentoo.org/wiki/Handbook:AMD64/Full/Installation#MAKEOPTS
> > >has a dire warning about memory usage...
> >
> > Yep, I've got the gcc-12.2.0 natively compiled on this netbook using
> > gcc-11.3.0, after 5+ days + a crash + 5more days.
> >
> > I set up a large swap and I've also set up the ccache which may
> > speedup a little after the crash.
> >
> > >>  Warning
> > >>
> > >> Using a large number of jobs can significantly impact memory
> > >> consumption. A good recommendation is to have at least 2 GiB of RAM
> > >> for every job specified (so, e.g. -j6 requires at least 12 GiB). To
> > >> avoid running out of memory, lower the number of jobs to fit the
> > >> available memory.
> > >>
> > >  You simply don't have enough ram.  You might reduce the pain and
> > >
> > > the
> > >
> > >swapping by trying something like the following in make.conf
> > >(assuming you haven't already done it)
> > >
> > >
> > >MAKEOPTS="-j1"
> >
> > I will try next time. Thanks.
> >
> > >> If this happens, what is the best way to reboot or shutdown?
> > >>
> > >  Try ye olde {CTRL}{ALT}{DEL}
> >
> > I remember that I did try "CTRL+ALT+DEL" in such situations before,
> > and most times it did not work but for one or two times it worked
> > occasionally. I will try it again next time.
>
> You could also use “Magic SysRQ”s[1] to reboot the system forcefully
> but somewhat controlled. The traditional sequence is:
>  r e i s u b    (raising elephants is so utterly boring)[2]
>
> [1] <https://wiki.gentoo.org/wiki/Magic_SysRQ>
> [2]
> <https://www.kernel.org/doc/html/latest/admin-guide/sysrq.html#what-are-the
> -command-keys>

Using MAKEOPTS="-j1" will help and a bigger swap will stop it crashing with 
OOM, but a more sensible solution is to compile and build big packages like 
gcc on a faster PC as binaries, then transfer and emerge on the slow PC with 
--usepkg, or --usepkgonly options.  More info:

https://wiki.gentoo.org/wiki/Binary_package_guide