[libvirt] [PATCH RESEND] qemu: Add support for overriding max threads per process limit

[Daniel P. Berrangé]

On Tue, Jul 23, 2019 at 07:56:56PM +0000, Jim Fehlig wrote:
> Some VM configurations may result in a large number of threads created by
> the associated qemu process which can exceed the system default limit. The
> maximum number of threads allowed per process is controlled by the pids
> cgroup controller and is set to 16k when creating VMs with systemd's
> machined service. The maximum number of threads per process is recorded
> in the pids.max file under the machine's pids controller cgroup hierarchy,
> e.g.
> 
> $cgrp-mnt/pids/machine.slice/machine-qemu\\x2d1\\x2dtest.scope/pids.max
> 
> Maximum threads per process is controlled with the TasksMax property of
> the systemd scope for the machine. This patch adds an option to qemu.conf
> which can be used to override the maximum number of threads allowed per
> qemu process. If the value of option is greater than zero, it will be set
> in the TasksMax property of the machine's scope after creating the machine.
> 
> Signed-off-by: Jim Fehlig <jfehlig at suse.com>
> ---
> 
> Rebase and resend of
> 
> https://www.redhat.com/archives/libvir-list/2019-June/msg00185.html
> 
>  src/lxc/lxc_cgroup.c               |  1 +
>  src/qemu/libvirtd_qemu.aug         |  1 +
>  src/qemu/qemu.conf                 | 10 ++++++++++
>  src/qemu/qemu_cgroup.c             |  1 +
>  src/qemu/qemu_conf.c               |  2 ++
>  src/qemu/qemu_conf.h               |  1 +
>  src/qemu/test_libvirtd_qemu.aug.in |  1 +
>  src/util/vircgroup.c               |  6 +++++-
>  src/util/vircgroup.h               |  1 +
>  src/util/virsystemd.c              | 24 +++++++++++++++++++++++-
>  src/util/virsystemd.h              |  3 ++-
>  tests/virsystemdtest.c             | 12 ++++++------
>  12 files changed, 54 insertions(+), 9 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange at redhat.com>


Regards,
Daniel
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