A recent commit (2f3a215) changed the parsing of /proc/cmdline to use a
shell array. Unfortunately, this introduced a bug: "read -ar line"
populates the shell variable $r, not $line. This breaks installation of
new loader entries:
# kernel-install add 3.17.1-304.fc21.x86_64 \
/boot/vmlinuz-3.17.1-304.fc21.x86_64
Could not determine the kernel command line parameters.
Please specify the kernel command line in /etc/kernel/cmdline!
This commit alters the read command to correctly populate the $line
array instead.
The term "priority" is misleading because higher levels have lower
priority. "Level" is clearer and shorter.
This commit touches only the textual descriptions, not function and variable
names themselves. "Priority" is used in various command-line switches and
protocol constants, so completly getting rid of "priority" is hard.
I also left "priority" in various places where the clarity suffered
when it was removed.
__attribute__((used)) is not enough to force static variables to
be carried over to a compiled program from a library. Mappings defined
in libsystemd-shared.a were not visible in the compiled binaries.
To ensure that the mappings are present in the final binary, the
tables are made non-static and are given a real unique name by which
they can be referenced.
To use a mapping defined not in the local compilation unit (e.g. in
a library) a reference to the mapping table is added. This is done
by including a declaration in the header file.
Expected values in test-engine are fixed to reflect the new mappings.
Depending on the link order, holes might appear in the body of
the sd_bus_errnomap section. Ignore them.
Adds a simple test to print the table to help with debugging such
issues in the future.
f7101b7368 copied some logic to prevent enabling masked units, but
also added a check which causes attempts to enable templated units to
fail. Since we know the logic beyond this check will properly handle
units which truly do not exist, we can rely on the unit file state
comparison to suffice for expressing the intent of f7101b7368.
ref: https://bugs.archlinux.org/task/42616
The raw socket sd_event_source used for DHCP server solicitations
was simply dropped on the floor when creating the new UDP socket
after a lease has been acquired. Clean it up properly so we're
not still listening and responding to events on it.
The option simply enables hashmap debugging by defining
ENABLE_HASHMAP_DEBUG.
I suggest developing new code with it enabled, to have the iterator checks.
This is a rewrite of the hashmap implementation. Its advantage is lower
memory usage.
It uses open addressing (entries are stored in an array, as opposed to
linked lists). Hash collisions are resolved with linear probing and
Robin Hood displacement policy. See the references in hashmap.c.
Some fun empirical findings about hashmap usage in systemd on my laptop:
- 98 % of allocated hashmaps are Sets.
- Sets contain 78 % of all entries, plain Hashmaps 17 %, and
OrderedHashmaps 5 %.
- 60 % of allocated hashmaps contain only 1 entry.
- 90 % of allocated hashmaps contain 5 or fewer entries.
- 75 % of all entries are in hashmaps that use trivial_hash_ops.
Clearly it makes sense to:
- store entries in distinct entry types. Especially for Sets - their
entries are the most numerous and they require the least information
to store an entry.
- have a way to store small numbers of entries directly in the hashmap
structs, and only allocate the usual entry arrays when the direct
storage is full.
The implementation has an optional debugging feature (enabled by
defining the ENABLE_HASHMAP_DEBUG macro), where it:
- tracks all allocated hashmaps in a linked list so that one can
easily find them in gdb,
- tracks which function/line allocated a given hashmap, and
- checks for invalid mixing of hashmap iteration and modification.
Since entries are not allocated one-by-one anymore, mempools are not
used for entries. Originally I meant to drop mempools entirely, but it's
still worth it to use them for the hashmap structs. My testing indicates
that it makes loading of units about 5 % faster (a test with 10000 units
where more than 200000 hashmaps are allocated - pure malloc: 449±4 ms,
mempools: 427±7 ms).
Here are some memory usage numbers, taken on my laptop with a more or
less normal Fedora setup after booting with SELinux disabled (SELinux
increases systemd's memory usage significantly):
systemd (PID 1) Original New Change
dirty memory (from pmap -x 1) [KiB] 2152 1264 -41 %
total heap allocations (from gdb-heap) [KiB] 1623 756 -53 %
Previously when a log message grew beyond the maximum AF_UNIX/SOCK_DGRAM
datagram limit we'd send an fd to a deleted file in /dev/shm instead.
Because the sender could still modify the file after delivery we had to
immediately copy the data on the receiving side.
With memfds we can optimize this logic, and also remove the dependency
on /dev/shm: simply send a sealed memfd around, and if we detect the
seal memory map the fd and use it directly.
