New documentation file is added. It should describe how systemd and libcgroup should work together and how to configure a system to have control groups created by libcgroup's cgconfig service.
I'm going to install this README into /usr/share/doc/libcgroup-*/. I know I am not Shakespeare and also English is not my mother language, feel free to comment also the style and grammar. Missing/wrong articles is my speciality :). Signed-off-by: Jan Safranek <jsafr...@redhat.com> --- README_systemd | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 68 insertions(+), 0 deletions(-) create mode 100644 README_systemd diff --git a/README_systemd b/README_systemd new file mode 100644 index 0000000..3bb2f6b --- /dev/null +++ b/README_systemd @@ -0,0 +1,68 @@ +Integration with systemd +======================== + +systemd is a system and service manager for Linux, compatible with SysV +and LSB init scripts. systemd heavily uses control groups to manage and control +services. + +Most of the libcgroup tools and APIs can be safely used on systems with systemd +without any problems. This document tries to describe how to configure systemd +and libcgroup so they can safely live together and mutually benefit from each +other. + +References +========== +[1] http://www.freedesktop.org/wiki/Software/systemd +Systemd home page. + +[2] http://www.freedesktop.org/wiki/Software/systemd/PaxControlGroups +This is the most usefult document describing systemd expectations on applications +(incl. libcgroup tools). + + +Compilation +=========== +As stated in [2], libcgroup should not touch "name=systemd" hierarchy. Compile +libcgroup with --enable-opaque-hierarchy configure option to do so: + +./configure --enable-opaque-hierarchy=name=systemd + +Libcgroup and all its tools won't then see the "name=systemd" hierarchy at all. +For example, lsgcroup won't show it's content and cgclear won't remove it. + + +Startup and services +==================== + +Systemd automatically mounts all available controllers on system boot ("cpu" +and "cpuacct" together in one hierarchy by default) and can automatically put +service processes into control groups with configured parameters - by default, +each service is automatically put into "cpu,cpuacct:/system/$service_name" +control group. System admin has full control on parameters of each group and +also which controllers are used. Consult systemd documentation, mainly +systemd.conf(5) and systemd.exec(5), for details. + +In vast majority of use cases, this should be enough and libcgroup does not need +to be used. + +For specific use cases, e.g. when different tree of control groups is needed, +libcgroup provides cgconfig service. This service can create arbitrary control +group hierarchies. In this case, follow these steps: + +1. Set 'DefaultControllers=' in /etc/systemd/system.conf so systemd does not +create control groups for services automatically. + +2. Prepare /etc/cgconfig.conf and enable cgconfig service. The service will +parse /etc/cgconfig.conf file during machine boot and create all control +groups which are defined in it. The service automatically sets '+t' ("sticky") +bit on tasks file as recommended in [2]. + +3. For each service that should start in specific control group, add following +lines into it's unit file: + After=cgconfig.service + ControlGroup=<name of the control group(s)> + +This ensures the service is started only after cgconfig creates necessary +hierarchy for it and also tells systemd into which control group should be the +service started. + ------------------------------------------------------------------------------ Cloud Services Checklist: Pricing and Packaging Optimization This white paper is intended to serve as a reference, checklist and point of discussion for anyone considering optimizing the pricing and packaging model of a cloud services business. Read Now! http://www.accelacomm.com/jaw/sfnl/114/51491232/ _______________________________________________ Libcg-devel mailing list Libcg-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libcg-devel
