Re: [systemd-devel] [ANNOUNCE] systemd v238

[Lennart Poettering]

On Fr, 09.03.18 07:57, Umut Tezduyar Lindskog (u...@tezduyar.com) wrote:

> Hello Zbigniew,
> 
> On Mon, Mar 5, 2018 at 11:37 PM, Zbigniew Jędrzejewski-Szmek
>  wrote:
> > Hi,
> >
> > systemd-238 has been tagged.
> >
> > https://github.com/systemd/systemd/archive/v238/systemd-238.tar.gz
> >
> > CHANGES WITH 238:
> >
> > * The MemoryAccounting= unit property now defaults to on. After
> >   discussions with the upstream control group maintainers we learnt
> >   that the negative impact of cgroup memory accounting on current
> >   kernels is finally relatively minimal, so that it should be safe 
> > to
> >   enable this by default without affecting system performance. 
> > Besides
> >   memory accounting only task accounting is turned on by default, 
> > all
> >   other forms of resource accounting (CPU, IO, IP) remain off for 
> > now,
> >   because it's not clear yet that their impact is small enough to 
> > move
> >   from opt-in to opt-out. We recommend downstreams to leave memory
> >   accounting on by default if kernel 4.14 or higher is are primarily
> >   used. On very resource constrained systems or when support for old
> >   kernels is a necessity, -Dmemory-accounting-default=false can be 
> > used
> >   to revert this change.
> 
> Are these optimisations for v1 or v2? Do you have more resource you
> can reference?

We made this change after discussing directly and personally with
Tejun, the upstream kernel cgroups go-to guy, who suggested it was OK
to turn it on now. Facebook has turned it on across its fleet now with
good results, and hence we came to the conclussion we can do the same
by default now.

Given that cgroups v1/v2 is primarily just a question of API (and not
controller implementation) I figure it should be fine on both, but
maybe ping Tejun directly.

Of course, I figure fb's fleet is very different from let#s say an
embedded device. If you play around with this on such devices from the
other end of the spectrum, please report issues if you do experience
major problems with this change of default after all...

Thanks,

Lennart

-- 
Lennart Poettering, Red Hat
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Re: [systemd-devel] [ANNOUNCE] systemd v238

[Umut Tezduyar Lindskog]

Hello Zbigniew,

On Mon, Mar 5, 2018 at 11:37 PM, Zbigniew Jędrzejewski-Szmek
 wrote:
> Hi,
>
> systemd-238 has been tagged.
>
> https://github.com/systemd/systemd/archive/v238/systemd-238.tar.gz
>
> CHANGES WITH 238:
>
> * The MemoryAccounting= unit property now defaults to on. After
>   discussions with the upstream control group maintainers we learnt
>   that the negative impact of cgroup memory accounting on current
>   kernels is finally relatively minimal, so that it should be safe to
>   enable this by default without affecting system performance. Besides
>   memory accounting only task accounting is turned on by default, all
>   other forms of resource accounting (CPU, IO, IP) remain off for now,
>   because it's not clear yet that their impact is small enough to move
>   from opt-in to opt-out. We recommend downstreams to leave memory
>   accounting on by default if kernel 4.14 or higher is are primarily
>   used. On very resource constrained systems or when support for old
>   kernels is a necessity, -Dmemory-accounting-default=false can be 
> used
>   to revert this change.

Are these optimisations for v1 or v2? Do you have more resource you
can reference?

Thanks,
UMUT

>
> * rpm scriptlets to update the udev hwdb and rules (%udev_hwdb_update,
>   %udev_rules_update) and the journal catalog 
> (%journal_catalog_update)
>   from the upgrade scriptlets of individual packages now do nothing.
>   Transfiletriggers have been added which will perform those updates
>   once at the end of the transaction.
>
>   Similar transfiletriggers have been added to execute any sysctl.d
>   and binfmt.d rules. Thus, it should be unnecessary to provide any
>   scriptlets to execute this configuration from package installation
>   scripts.
>
> * systemd-sysusers gained a mode where the configuration to execute is
>   specified on the command line, but this configuration is not 
> executed
>   directly, but instead it is merged with the configuration on disk,
>   and the result is executed. This is useful for package installation
>   scripts which want to create the user before installing any files on
>   disk (in case some of those files are owned by that user), while
>   still allowing local admin overrides.
>
>   This functionality is exposed to rpm scriplets through a new
>   %sysusers_create_package macro. Old %sysusers_create and
>   %sysusers_create_inline macros are deprecated.
>
>   A transfiletrigger for sysusers.d configuration is now installed,
>   which means that it should be uncessary to call systemd-sysusers 
> from
>   package installation scripts, unless the package installs any files
>   owned by those newly-created users, in which case
>   %sysusers_create_package should be used.
>
> * Analogous change has been done for systemd-tmpfiles: it gained a 
> mode
>   where the command-line configuration is merged with the 
> configuration
>   on disk. This is exposed as the new %tmpfiles_create_package macro,
>   and %tmpfiles_create is deprecated. A transfiletrigger is installed
>   for tmpfiles.d, hence it should be unnecessary to call 
> systemd-tmpfiles
>   from package installation scripts.
>
> * sysusers.d configuration for a user may now also specify the group
>   number, in addition to the user number ("u username 123:456"), or
>   without the user number ("u username -:456").
>
> * Configution items for systemd-sysusers can now be specified as
>   positional arguments when the new --inline switch is used.
>
> * The login shell of users created through sysusers.d may now be
>   specified (previously, it was always /bin/sh for root and
>   /sbin/nologin for other users).
>
> * systemd-analyze gained a new --global switch to look at global user
>   configuration. It also gained a unit-paths verb to list the unit 
> load
>   paths that are compiled into systemd (which can be used with
>   --systemd, --user, or --global).
>
> * udevadm trigger gained a new --settle/-w option to wait for any
>   triggered events to finish (but just those, and not any other events
>   which are triggered meanwhile).
>
> * The action that systemd-logind takes when the lid is closed and the
>   machine is connected to external power can now be configured using
>   HandleLidSwitchExternalPower= in logind.conf. Previously, this 
> action
>   was determined by HandleLidSwitch=, and, for backwards 
> compatibility,
>   is still is, if HandleLidSwitchExternalPower= is not explicitly set.
>
> * 

[systemd-devel] [ANNOUNCE] systemd v238

[Zbigniew Jędrzejewski-Szmek]

Hi,

systemd-238 has been tagged.

https://github.com/systemd/systemd/archive/v238/systemd-238.tar.gz

CHANGES WITH 238:

* The MemoryAccounting= unit property now defaults to on. After
  discussions with the upstream control group maintainers we learnt
  that the negative impact of cgroup memory accounting on current
  kernels is finally relatively minimal, so that it should be safe to
  enable this by default without affecting system performance. Besides
  memory accounting only task accounting is turned on by default, all
  other forms of resource accounting (CPU, IO, IP) remain off for now,
  because it's not clear yet that their impact is small enough to move
  from opt-in to opt-out. We recommend downstreams to leave memory
  accounting on by default if kernel 4.14 or higher is are primarily
  used. On very resource constrained systems or when support for old
  kernels is a necessity, -Dmemory-accounting-default=false can be used
  to revert this change.

* rpm scriptlets to update the udev hwdb and rules (%udev_hwdb_update,
  %udev_rules_update) and the journal catalog (%journal_catalog_update)
  from the upgrade scriptlets of individual packages now do nothing.
  Transfiletriggers have been added which will perform those updates
  once at the end of the transaction.

  Similar transfiletriggers have been added to execute any sysctl.d
  and binfmt.d rules. Thus, it should be unnecessary to provide any
  scriptlets to execute this configuration from package installation
  scripts.

* systemd-sysusers gained a mode where the configuration to execute is
  specified on the command line, but this configuration is not executed
  directly, but instead it is merged with the configuration on disk,
  and the result is executed. This is useful for package installation
  scripts which want to create the user before installing any files on
  disk (in case some of those files are owned by that user), while
  still allowing local admin overrides.

  This functionality is exposed to rpm scriplets through a new
  %sysusers_create_package macro. Old %sysusers_create and
  %sysusers_create_inline macros are deprecated.

  A transfiletrigger for sysusers.d configuration is now installed,
  which means that it should be uncessary to call systemd-sysusers from
  package installation scripts, unless the package installs any files
  owned by those newly-created users, in which case
  %sysusers_create_package should be used.

* Analogous change has been done for systemd-tmpfiles: it gained a mode
  where the command-line configuration is merged with the configuration
  on disk. This is exposed as the new %tmpfiles_create_package macro,
  and %tmpfiles_create is deprecated. A transfiletrigger is installed
  for tmpfiles.d, hence it should be unnecessary to call 
systemd-tmpfiles
  from package installation scripts.

* sysusers.d configuration for a user may now also specify the group
  number, in addition to the user number ("u username 123:456"), or
  without the user number ("u username -:456").

* Configution items for systemd-sysusers can now be specified as
  positional arguments when the new --inline switch is used.

* The login shell of users created through sysusers.d may now be
  specified (previously, it was always /bin/sh for root and
  /sbin/nologin for other users).

* systemd-analyze gained a new --global switch to look at global user
  configuration. It also gained a unit-paths verb to list the unit load
  paths that are compiled into systemd (which can be used with
  --systemd, --user, or --global).

* udevadm trigger gained a new --settle/-w option to wait for any
  triggered events to finish (but just those, and not any other events
  which are triggered meanwhile).

* The action that systemd-logind takes when the lid is closed and the
  machine is connected to external power can now be configured using
  HandleLidSwitchExternalPower= in logind.conf. Previously, this action
  was determined by HandleLidSwitch=, and, for backwards compatibility,
  is still is, if HandleLidSwitchExternalPower= is not explicitly set.

* journalctl will periodically call sd_journal_process() to make it
  resilient against inotify queue overruns when journal files are
  rotated very quickly.

* Two new functions in libsystemd — sd_bus_get_n_queued_read and
  sd_bus_get_n_queued_write — may be used to check the number of
  pending bus messages.

* systemd gained a new