Re: How to prevent rtkit from giving firefox higher priority?
On Tue, Jan 16, 2024 at 02:17:05PM +0100, hw wrote:
> On Tue, 2024-01-16 at 08:03 -0500, Greg Wooledge wrote:
> > On Tue, Jan 16, 2024 at 01:43:23PM +0100, hw wrote:
> > > There's only a bunch of links in that directory, apparently all
> > > pointing to files that don't exist. Don't you have that?
> >
> > unicorn:~$ ls -l /run/user/1000/systemd/units
> > total 0
> > lrwxrwxrwx 1 greg greg 32 Jan 4 10:33 invocation:at-spi-dbus-bus.service -> bfec6466520a4586b8c9205c235ccc92
> > [...]
> > I guess that's normal, then. It seems they're using the symlink target
> > as the actual *data*, not a link to another file that contains the data.
> > Why? I have no idea. I seem to recall one of the BSDs doing something
> > like this, but I never fully understood the rationale. Something about
> > atomic operations, maybe?
> >
>
> I consider it as alarming rather than normal when I can't access data
> on my own computer.
You can access it just fine. You just don't *understand* it. (Neither
do I.)
> And I do want to know what this unit file for firefox contains and
> does and how it is being brought about.
If it's a symlink whose name begins with "invocation:" and whose target
is a 32-hex-digit (128-bit) value, like the one shown above, then
you are seeing everything there is to see. I don't know what the 128-bit
number is used for, but that number *is* the data. Of that, I'm certain.
I did a bit of Google searching, and I think this is something called
an "InvocationID".
> > lrwxrwxrwx 1 greg greg 32 Jan 4 10:33 invocation:at-spi-dbus-bus.service -> bfec6466520a4586b8c9205c235ccc92
unicorn:~$ systemctl --user show -p InvocationID at-spi-dbus-bus.service
InvocationID=bfec6466520a4586b8c9205c235ccc92
<https://sleeplessbeastie.eu/2022/07/01/how-to-display-systemd-journal-for-specific-service-since-it-started/>
describes this as "a unique 128-bit ID identifying each runtime cycle
of the unit".
There is also a man page systemd-id128(1) ("man systemd-id128") but it
doesn't describe things in a way I can currently understand. It seems
to reference another page sd-id128(3) which I do not have, but which
I can find online at
<https://manpages.debian.org/bookworm/libsystemd-dev/sd-id128.3.en.html>
... which, OK, that's pretty boring. What I cannot find anywhere is
a basic explanation of *what this ID is used for*.
Maybe it's just a fancy PID? I dunno, it's all very shrouded in mystery.
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