The current use of literal + replaceable is pretty ugly as it usually
ends up with cgroup_disable= rendered in quotes, which looks really
weird, and this doesn't conform with others of a similar type (for
example, the earlier `DefaultDependencies=no` discussion in the same
file.
The new systemd analyze code dependend on routines provided by
libseccomp even if HAVE_SECCOMP is false. This expands the code disabled
in analyze-security to make sure we don't depend on seccomp.
The table cell reusing code is supposed to be an internal memory
optimization, and not more. This means behaviour should be the same as
if we wouldn't reuse cells.
This adds a per-cell option for uppercasing displayed strings.
Implicitly turn this on for the header row. The fact that we format the
table header in uppercase is a formatting thing after all, hence should
be applied by the formatter, i.e. the table display code.
Moreover, this provides us with the benefit that we can more nicely
reuse the specified table headers as JSON field names, like we already
do: json field names are usually not uppercase.
Since .timespan and .timestamp are unionized on top of each other this
doesn't actually matter, but it is still more correct to address it
under it's correct name.
We want it for global variables, which LLVM supports and GCC currently
does not (GCC does support it for functions, but we care about global
variables here).
Why is this relevant? When asan is used global variables are padded with
hotzones before and after. But we can't have that for the registration
variables we place in special ELF sections: we want them tightly packed
so that we can iterate through them.
Note that for gcc this isn't an issue, as it will pack stuff in
non-standard sections anyway, even if asan is used.
Some controllers (like the CPU controller) have a performance cost that
is non-trivial on certain workloads. While this can be mitigated and
improved to an extent, there will for some controllers always be some
overheads associated with the benefits gained from the controller.
Inside Facebook, the fix applied has been to disable the CPU controller
forcibly with `cgroup_disable=cpu` on the kernel command line.
This presents a problem: to disable or reenable the controller, a reboot
is required, but this is quite cumbersome and slow to do for many
thousands of machines, especially machines where disabling/enabling a
stateful service on a machine is a matter of several minutes.
Currently systemd provides some configuration knobs for these in the
form of `[Default]CPUAccounting`, `[Default]MemoryAccounting`, and the
like. The limitation of these is that Default*Accounting is overrideable
by individual services, of which any one could decide to reenable a
controller within the hierarchy at any point just by using a controller
feature implicitly (eg. `CPUWeight`), even if the use of that CPU
feature could just be opportunistic. Since many services are provided by
the distribution, or by upstream teams at a particular organisation,
it's not a sustainable solution to simply try to find and remove
offending directives from these units.
This commit presents a more direct solution -- a DisableControllers=
directive that forcibly disallows a controller from being enabled within
a subtree.
This adds a depth-first version of unit_realize_cgroup_now which can
only do depth-first disabling of controllers, in preparation for the
DisableController= directive.
systemd currently doesn't really expend much effort in disabling
controllers. unit_realize_cgroup_now *may* be able to disable a
controller in the basic case when using cgroup v2, but generally won't
manage as downstream dependents may still use it.
This code doesn't add any logic to fix that, but it starts the process
of moving to have a breadth-first version of unit_realize_cgroup_now for
enabling, and a depth-first version of unit_realize_cgroup_now for
disabling.
