[libvirt] [PATCH 07/13] Create + setup cgroups atomically for QEMU process

Eric Blake eblake at redhat.com
Tue Jul 23 17:44:13 UTC 2013


On 07/23/2013 09:21 AM, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange at redhat.com>
> 
> Currently the QEMU driver creates the VM's cgroup prior to
> forking, and then uses a virCommand hook to move the child
> into the cgroup. This won't work with systemd whose APIs
> do the creation of cgroups + attachment of processes atomically.
> 
> Fortunately we have a handshake taking place between the
> QEMU driver and the child process prior to QEMU being exec()d,
> which was introduced to allow setup of disk locking. By good
> fortune this synchronization point can be used to enable the
> QEMU drivedr to do atomic setup of cgroups removing the use

s/drivedr/driver/

> of the hook script.
> 
> Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> ---
>  src/qemu/qemu_cgroup.c  | 12 +++++++++---
>  src/qemu/qemu_process.c | 39 +++++++++++++++++----------------------
>  2 files changed, 26 insertions(+), 25 deletions(-)
> 

ACK.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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