Before, we would initialize many fields twice: first
by filling the structure with zeros, and then a second
time with the real values. We can let the compiler do
the job for us, avoiding one copy.
A downside of this patch is that text gets slightly
bigger. This is because all zero() calls are effectively
inlined:
$ size build/.libs/systemd
text data bss dec hex filename
before 897737 107300 2560 1007597 f5fed build/.libs/systemd
after 897873 107300 2560 1007733 f6075 build/.libs/systemd
… actually less than 1‰.
A few asserts that the parameter is not null had to be removed. I
don't think this changes much, because first, it is quite unlikely
for the assert to fail, and second, an immediate SEGV is almost as
good as an assert.
Internally we store all time values in usec_t, however parse_usec()
actually was used mostly to parse values in seconds (unless explicit
units were specified to define a different unit). Hence, be clear about
this and name the function about what we pass into it, not what we get
out of it.
Readahead has all sorts of bad side effects depending on your
storage media. On rotating disks, it may be degrading startup
performance if enough requests are queued spanning linearly
over all blocks early at boot, and mount, blkid and friends
want to insert reads to the start of these block devices after.
The end result is that on spinning disks with ext3/4 that udev
and mounts take a very long time, and nothing really happens until
readahead is completely finished.
This has the net effect that the CPU is almost entirely idle
for the entire period that readahead is working. We could have
finished starting up quite a lot of services in this time if
we were smarter at how we do readahead.
This patch sorts all requests into 2 second "chunks" and sub-sorts
each chunk by block. This adds a single cross-drive seek per "chunk"
but has the benefit that we will have a lot of the blocks we need
early on in the boot sequence loaded into memory faster.
For a comparison of how before/after bootcharts look (ext4 on a
mobile 5400rpm 250GB drive) please look at:
http://foo-projects.org/~sofar/blocked-tests/
There are bootcharts in the "before" and "after" folders where you
should be able to see that many low-level services finish 5-7
seconds earlier with the patch applied (after).
It is only needed in files designed to be usable in standalone
compilation. In those files the #ifdefinery is indented. When
compiling in-tree, GNU_SOURCE is always defined, so remove one
definition.
[zj: Reworded message s/to watch/to add watch on/ to make it clear
that it was the watch init action that failed, and not the
"process of watching". I think this way it'll be clearer to
people who don't know what inotify does.]
also a number of minor fixups and bug fixes: spelling, oom errors
that didn't print errors, not properly forwarding error codes,
few more consistency issues, et cetera
glibc/glib both use "out of memory" consistantly so maybe we should
consider that instead of this.
Eliminates one string out of a number of binaries. Also fixes extra newline
in udev/scsi_id
#pragma once has been "un-deprecated" in gcc since 3.3, and is widely supported
in other compilers.
I've been using and maintaining (rebasing) this patch for a while now, as
it annoyed me to see #ifndef fooblahfoo, etc all over the place,
almost arrogant about the annoyance of having to define all these names to
perform a commen but neccicary functionality, when a completely superior
alternative exists.
I havn't sent it till now, cause its kindof a style change, and it is bad
voodoo to mess with style that has been established by more established
editors. So feel free to lambast me as a crazy bafoon.
v2 - preserve externally used headers
since the binaries share much of the same code and we better load only
one binary instead of two from disk at early boot let's merge the three
readahead binaries into one. This also allows us to drop a lot of
duplicated code.
This patch adds code to compile 'systemd-readahead-analyze' and install
it into $bindir.
Use this program to parse the contents of the readahead pack file, or
an arbitrary pack file and display which files are listed in it, and
how much of the files are requested to be readahead.
This code is not new - it's partially taken from sreadahead (formerly
maintained by Arjan van der Ven and me, and was originally written
by me), and adapted with the right bits to parse the systemd
readahead pack files, which are slightly different in format.
v2 adds a common READAHEAD_PACK_FILE_VERSION used in all the code
to provide a quick way to assure all these programs are always
synchronized. v3 fixes the integer math.
If the inode nr for each file is available in the pack file we can
easily detect replaced files (like they result from package upgrades)
which we can then skip to readahead.
While collecting readahead data we want to know exactly what userspace
accesses unblurred by the kernel's read_ahead_kb. Hence lower this
during collection, and raise it afterwards.
This is mostly based on ideas and code by Auke Kok.
We finally got the OK from all contributors with non-trivial commits to
relicense systemd from GPL2+ to LGPL2.1+.
Some udev bits continue to be GPL2+ for now, but we are looking into
relicensing them too, to allow free copy/paste of all code within
systemd.
The bits that used to be MIT continue to be MIT.
The big benefit of the relicensing is that closed source code may now
link against libsystemd-login.so and friends.
Zbigniew Jędrzejewski-Szmek