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Backports of patch from systemd git to stable distributions
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Vito Caputo 7a24f3bf2f journal: coalesce ftruncate()s in 250ms windows 
Prior to this change every journal append causes an ftruncate() for the
sake of inotify propagation of the mmap-based writes.

With this change the notification is deferred up to ~250ms, coalescing
any repeated journal writes during the deferred period into a single
ftruncate().  The ftruncate() call isn't free and doing it on every
append adds unnecessary overhead and latency in the journald event loop.

Introduces journal_file_enable_post_change_timer() which manages a
timer on the provided sd-event instance for scheduling coalesced
ftruncates.  The ftruncate() behavior is unchanged unless
journal_file_enable_post_change_timer() is called on the JournalFile.

While not a tremendous improvement, profiling systemd-journald event loop
latencies using instrumentation as introduced by 34b8751 it was observed that
coalescing the ftruncates was low-hanging fruit worth pursuing.

Note orders 12 and 13 shifting left into order 11 and order 6 dipping into
order 5:

Unmodified:
     log2(us)   1 2 3  4 5  6   7   8  9   10 11   12   13 14 15 16 17 18 19
                -----------------------------------------------------------
[10685.414572]  0 0 0  0 38 602 61  2  290 60 1643 2554 13 1  4  1  0  0  1
[10690.415114]  0 0 0  0 0  646 54  7  309 44 2073 2148 17 1  3  0  0  0  1
[10695.415509]  0 0 0  0 1  650 73  3  324 37 2071 2270 9  0  0  1  0  1  0
[10700.416297]  0 0 0  0 0  659 50  4  318 38 2111 2152 6  0  1  0  0  1  1
[10705.417136]  0 0 0  0 2  660 48  4  320 38 2129 2146 12 1  1  0  0  1  1
[10710.489114]  0 0 0  0 0  673 38  3  321 37 1925 2339 7  0  0  0  0  1  1
[10715.489613]  0 0 0  0 3  656 64  8  317 48 2365 2007 7  0  0  0  0  0  1

Coalesced:
     log2(us)   1 2 3  4 5  6   7   8  9   10 11   12   13 14 15 16 17 18 19
                -----------------------------------------------------------
[ 6169.161360]  0 0 0  1 24 786 54  11 389 24 4192 771  6  4  0  0  1  0  1
[ 6174.161705]  0 0 0  1 18 800 35  6  380 27 3977 893  3  1  0  0  1  0  1
[ 6179.162741]  0 0 0  1 28 768 51  4  391 16 3998 831  5  3  0  0  0  0  2
[ 6184.162856]  0 0 0  0 19 770 60  2  376 26 3795 1004 9  5  1  0  1  0  1
[ 6189.163279]  0 0 0  0 28 761 49  7  372 27 3729 1056 3  2  0  0  1  0  1
[ 6194.164255]  0 0 0  0 25 785 49  7  394 19 3996 908  6  3  2  0  0  0  1
[ 6199.164658]  0 0 0  0 29 797 35  5  389 18 3995 898  3  4  1  1  1  0  1

The remaining high-order delays are a result of the synchronous fsyncs in
systemd-journald, beyond the scope of this commit.
2016-01-14 16:36:07 -08:00
catalog catalog: move danish catalog into the right place, and drop DOS line breaks 2015-11-13 13:52:00 +01:00
coccinelle coccinelle: additional errno.cocci hunk 2015-11-09 20:01:06 +01:00
docs docs: add .gitignore 2015-07-06 17:47:38 +02:00
factory/etc factory: remove broken pam_limits 2014-07-30 15:21:54 +02:00
hwdb hwdb: update 2015-11-14 09:54:17 +01:00
m4 build-sys: Check behavior of -Werror=shadow before deciding to use it 2015-09-22 09:54:33 -07:00
man importd: drop dkr support 2015-12-10 16:54:41 +01:00
network networkd: emit DNS/NTP/Timezone info via DHCP server by default 2015-08-27 16:47:26 +02:00
po Merge pull request #1983 from dmedri/master 2015-11-22 22:34:37 +01:00
rules rfkill: rework and make it listen on /dev/rfkill 2015-10-01 16:21:09 +02:00
shell-completion importd: drop dkr support 2015-12-10 16:54:41 +01:00
src journal: coalesce ftruncate()s in 250ms windows 2016-01-14 16:36:07 -08:00
sysctl.d sysctl: use %P instead of %p in core pattern 2015-11-17 17:32:49 +01:00
system-preset preset: enable machines.target by default 2014-12-29 17:36:57 +01:00
sysusers.d build: fix systemd-journal-upload installation 2015-12-09 03:48:56 +00:00
test Merge pull request #2056 from evverx/expose-soft-limits-on-the-bus 2015-12-10 11:20:03 +01:00
tmpfiles.d tmpfiles: set acls on system.journal explicitly 2015-11-29 23:38:09 -05:00
tools man: include the target name when linking to man pages in html output 2015-11-22 23:54:29 -05:00
units Set user@.service TasksMax=infinity 2015-11-22 23:05:23 +01:00
xorg login: support user-bus on dbus1 2015-08-31 18:12:37 +02:00
.dir-locals.el Keep emacs configuration in one configuration file. 2011-03-08 01:53:46 +01:00
.editorconfig add editorconfig configuration 2015-11-23 12:32:59 +01:00
.gitattributes git: indicate that tabs are never OK in the systemd tree 2013-10-30 02:25:38 +01:00
.gitignore Merge pull request #2115 from dvdhrm/rbtree 2015-12-08 17:31:09 +01:00
.mailmap NEWS: add more stuff, and reorder things a bit 2015-11-13 13:59:50 +01:00
.travis.yml remove gudev and gtk-doc 2015-06-03 00:22:53 +02:00
.vimrc vimrc: add warning about dangerous exrc mode 2015-11-23 19:31:00 +01:00
.ycm_extra_conf.py ycm: update flag blacklist 2014-06-04 15:41:10 -04:00
autogen.sh terminal: drop unfinished code 2015-07-27 20:15:34 +02:00
CODING_STYLE CODING_STYLE: elaborate on usage of C99 fixed size integer types 2015-11-10 17:31:30 +01:00
configure.ac importd: drop dkr support 2015-12-10 16:54:41 +01:00
DISTRO_PORTING build-sys: warn if people don't change the default NTP servers when building systemd 2015-07-11 14:24:29 -03:00
LICENSE.GPL2 relicense to LGPLv2.1 (with exceptions) 2012-04-12 00:24:39 +02:00
LICENSE.LGPL2.1 licence: remove references to old FSF address 2012-12-17 11:41:31 +01:00
Makefile-man.am tree-wide: expose "p"-suffix unref calls in public APIs to make gcc cleanup easy 2015-11-27 19:19:36 +01:00
Makefile.am importd: drop dkr support 2015-12-10 16:54:41 +01:00
NEWS NEWS: add in missing NEWS entry for 228 feature RemainAfterElapse= 2015-11-18 17:04:04 +01:00
README README: Recommend kinvolk regarding engineering services 2015-12-10 11:57:08 +01:00
README.md README.md: add Coverity scan status badge 2015-06-08 13:26:54 +02:00
TODO Merge pull request #2096 from teg/resolved-cache 2015-12-10 20:48:42 +01:00

README.md

systemd - System and Service Manager

Build Status
Coverity Scan Status

Details

  • General information about systemd can be found in the systemd Wiki
  • Information about build requirements are provided in the README file