Measure and slim down systemd and udev - Revision history

Tim Bird: /* Description */ fix bullet list

2012-04-18T00:05:38Z

‎Description: fix bullet list

Hisaomunakata at 04:35, 14 April 2012

2012-04-14T04:35:54Z

Hisaomunakata at 04:35, 14 April 2012

2012-04-14T04:35:09Z

Hisaomunakata: Created page with "; Summary: Measure and slim down systemd and udev ; Proposer: Gustavo Sverzut Barbieri == Description == Systemd is a system and service manager for L..."

2012-04-14T04:33:35Z

Created page with "; Summary: Measure and slim down systemd and udev ; Proposer: Gustavo Sverzut Barbieri <barbieri@profusion.mobi> == Description == Systemd is a system and service manager for L..."

New page

; Summary: Measure and slim down systemd and udev

; Proposer: Gustavo Sverzut Barbieri <barbieri@profusion.mobi>

== Description ==
Systemd is a system and service manager for Linux featuring aggressive
parallelization capabilities, uses socket and D-Bus activation for
starting services, offers on-demand starting of daemons, keeps track
of processes using Linux control groups, supports snapshotting and
restoring of the system state, maintains mount and automount points
and implements an elaborate transactional dependency-based service
control logic. It can work as a drop-in replacement for sysvinit.

Udev is the device manager for the Linux kernel, receiving hotplug
events, firmware load requests, dynamically loading modules and so on.
Udev and systemd communicates heavily and can boost each other
capabilities, such as properly assigning labels and users to hardware,
starting services when devices are found, among others. Due this, udev
and systemd merged into a single project to highly simplify the
project interaction and share codebase.

Both projects have a great potential to simplify and speed up the
Linux boot process, yet they are claimed to be heavyweight for
embedded system without a clear reason or numbers, just speculations.

The first part of this project is to measure the impact of both
systemd and udev in a system compared to the said smallest stack up to
date: busybox init and mdev. The comparison should account, for each
component, disk footprint, runtime memory and features. Systemd should
have always two measures: the default (full-feature) and stripped. The
stripped version will include no extras such as ACL, audit, tcpwrap or
logind. The comparison should also highlight features of each
measured component. The result of this work is a clear view of the
systemd and udev impact compared to a barebone solution, with concrete
numbers.

The second part of this project is to slim down both systemd and udev
based on findings of the measurements. Although already configurable
to some degree, both systemd and udev should receive more compile time
options to cope with embedded systems. The developers already agreed
to accept such options if they prove to be worth and our numbers from
the first part of this project are important here.

The key features of systemd to be analysed and, if proven to be heavy,
slimmed down are:
* journald to be made optional, with logs going to /dev/kmsg;
* cgroups usage to be made optional, loosing all grouping and
isolation it allows;
* dbus usage to be made optional, removing the runtime management
with systemctl.
* internal structures and state.

The last part of this project is to write a document on systemd
targeted at embedded systems and clarifying what parts can be disabled
and their effect. It already comes with 28 binaries that can be
optionally removed and a handful of features that can be disabled.

== Related work ==
* http://www.freedesktop.org/wiki/Software/systemd
* http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev/udev.html

== Scope ==
# Measure systemd and udev compared to busybox init and mdev: 1 person-week
# Slim down systemd and udev based on measured numbers: 4-12
person-weeks (can be time-based instead of feature/size based)
# Document systemd and udev for embedded systems and how slim them: 1
person-week
Total: 6-14 person-weeks

== Contractor Candidates ==
Gustavo Sverzut Barbieri <barbieri@profusion.mobi> (or co-workers from
ProFUSION embedded systems)

== Comments ==

@@ Line 44: / Line 44: @@
 The key features of systemd to be analysed and, if proven to be heavy,
 slimmed down are:
- * journald to be made optional, with logs going to /dev/kmsg;
+* journald to be made optional, with logs going to /dev/kmsg;
- * cgroups usage to be made optional, loosing all grouping and
+* cgroups usage to be made optional, loosing all grouping and isolation it allows;
-isolation it allows;
+* dbus usage to be made optional, removing the runtime management with systemctl.
- * dbus usage to be made optional, removing the runtime management
+* internal structures and state.
 with systemctl.
- * internal structures and state.
 The last part of this project is to write a document on systemd

@@ Line 62: / Line 62: @@
 == Scope ==
 # Measure systemd and udev compared to busybox init and mdev: 1 person-week
-# Slim down systemd and udev based on measured numbers: 4-12
+# Slim down systemd and udev based on measured numbers: 4-12 person-weeks (can be time-based instead of feature/size based)
-person-weeks (can be time-based instead of feature/size based)
+# Document systemd and udev for embedded systems and how slim them: 1 person-week
 # Document systemd and udev for embedded systems and how slim them: 1
 person-week
 Total: 6-14 person-weeks
@@ Line 74: / Line 72: @@
 == Comments ==
 [[Category:Project proposals 2012]]