Re: [libvirt] [RFC PATCH 01/17] qemu: setup shared memory without explicit numa configuration

On 08/16/2018 06:31 AM, Marc-André Lureau wrote: > Hi > > On Thu, Aug 16, 2018 at 4:35 AM, John Ferlan <jferlan(a)redhat.com&gt; wrote: >> >> >> On 07/13/2018 09:28 AM, marcandre.lureau(a)redhat.com wrote: >>> From: Marc-André Lureau <marcandre.lureau(a)redhat.com&gt; >>> >>> When a domain is configured with 'shared' memory backing: >>> >>> <memoryBacking> >>> <access mode='shared'/> >>> </memoryBacking> >>> >>> But no explicit NUMA configuration, let's configure a shared memory >>> backend associated with default -numa. >>> >>> Signed-off-by: Marc-André Lureau <marcandre.lureau(a)redhat.com&gt; >>> --- >>> src/qemu/qemu_command.c | 100 ++++++++++++------ >>> .../fd-memory-no-numa-topology.args | 4 + >>> 2 files changed, 73 insertions(+), 31 deletions(-) >>> >> >> NUMA, memory backends, and hugepages - not in my wheelhouse of >> knowledge. Hopefully Michal and/or Pavel will take a look! >> >> Is it possible someone may not want this type of thing to happen? Is > > I assume someone that sets 'shared' memory mode may consider this as a bug fix. > >> there an upside or downside to this? What happens "today" when not > > You get non-shared memory > So today someone asks for "shared" and then end up with "non-shared"? I don't think that's apparent from the "access" description in: https://libvirt.org/formatdomain.html#elementsMemoryBacking Then again, not in my wheelhouse of knowledge, so maybe that's just one of those givens. Of course that perhaps goes to your first answer of this being a "bug fix". Not something that's apparent from the existing documentation or commit description though. This probably should have been it's own separate patch and not included in this series.