Since 56b2970 has proven to be a no-go for us, as it breaks existing
links, let's embrace the trailing slash and use absolute links
everywhere for our pages. This way we'll get around browser cleverly
appending the relative link to the current location (since it ends with
a slash), and given our docs/ layout is flat it's not much of a hassle
either.
Converted using this beauty:
$ sed -ri 's/(\[.+\]\()([A-Z_]+\))/\1\/\2/g' *.md
Resolves: #32088 (again) and #32310
This reverts commit 5e8ff010a1.
This broke all the URLs, we can't have that. (And actually, we probably don't
_want_ to make the change either. It's nicer to have all the pages in one
directory, so one doesn't have to figure out to which collection the page
belongs.)
Currently we spawn services by forking a child process, doing a bunch
of work, and then exec'ing the service executable.
There are some advantages to this approach:
- quick: we immediately have access to all the enourmous amount of
state simply by virtue of sharing the memory with the parent
- easy to refactor and add features
- part of the same binary, will never be out of sync
There are however significant drawbacks:
- doing work after fork and before exec is against glibc's supported
case for several APIs we call
- copy-on-write trap: anytime any memory is touched in either parent
or child, a copy of that page will be triggered
- memory footprint of the child process will be memory footprint of
PID1, but using the cgroup memory limits of the unit
The last issue is especially problematic on resource constrained
systems where hard memory caps are enforced and swap is not allowed.
As soon as PID1 is under load, with no page out due to no swap, and a
service with a low MemoryMax= tries to start, hilarity ensues.
Add a new systemd-executor binary, that is able to receive all the
required state via memfd, deserialize it, prepare the appropriate
data structures and call exec_child.
Use posix_spawn which uses CLONE_VM + CLONE_VFORK, to ensure there is
no copy-on-write (same address space will be used, and parent process
will be frozen, until exec).
The sd-executor binary is pinned by FD on startup, so that we can
guarantee there will be no incompatibilities during upgrades.
We used both "qemu" and "QEMU", let's use the lower-case version everywhere
since it's also the name of the binary and the version that people are
most familiar with.
The stuff under test/ is not only for the integeration tests, but also
for various other test-related stuff, so adjust the docs a bit.
I have no idea if this is going to cause rendering problems, and it is fairly
hard to check. So let's just merge this, and if it github markdown processor
doesn't like it, revert.
