[libvirt] [PATCH] qemu: Use memory-object-file when needed

[Shivaprasad bhat]

Hi Martin,

I see, the memory from the node specified in numatune is used correctly.
Wit your change memory-backend-file is used to enforce that

But, I see the migrations from old versions(my case, 1.2.5) seems to fail
as there was no backend-file before and only backend-ram.

Unknown ramblock "ppc_spapr.ram", cannot accept migration
2016-01-13T08:16:17.488267Z qemu-system-ppc64-hp: error while loading state
for instance 0x0 of device 'ram'

Should we be using -mem-path /dev/hugepages/libvirt/qemu along with
memory-backend-ram instead?

Thanks,
Shivaprasad
My guest :  https://paste.fedoraproject.org/310103/67350814/
PS: I have some private changes in 1.2.5 but I believe that doesn't affect
anything here. Please let me know if you cant hit it.

On Tue, Jan 12, 2016 at 11:28 PM, Martin Kletzander <mkletzan at redhat.com>
wrote:

> On Tue, Jan 12, 2016 at 06:48:02PM +0100, Martin Kletzander wrote:
>
>> We were missing a check for '!nodemask' in the condition that decides
>> whether we need memory-object-file or not.  We only used userNodeset,
>> but forgot that we might need to use nodemask even if that's not set.
>>
>> Even though there was a test for this, the args file was incorrect, so
>> it is very nicely visible what this change does function-wise.  Even
>> with that I added the same test but instead of auto nodeset I specified
>> one in numatune/memory just to make sure it fixes the problem.
>>
>> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
>> ---
>> src/qemu/qemu_command.c                            |  3 ++-
>> .../qemuxml2argv-numatune-auto-prefer.args         |  4 ++-
>> ...emuxml2argv-numatune-hugepages-no-memnode.args} |  3 ++-
>> .../qemuxml2argv-numatune-hugepages-no-memnode.xml | 29
>> ++++++++++++++++++++++
>> tests/qemuxml2argvtest.c                           |  2 ++
>> 5 files changed, 38 insertions(+), 3 deletions(-)
>> copy tests/qemuxml2argvdata/{qemuxml2argv-numatune-auto-prefer.args =>
>> qemuxml2argv-numatune-hugepages-no-memnode.args} (72%)
>> create mode 100644
>> tests/qemuxml2argvdata/qemuxml2argv-numatune-hugepages-no-memnode.xml
>>
>>
> I forgot to run 'git commit --amend' before 'git send-email', so this
> needs to be considered squashed in:
>
> diff --git c/src/qemu/qemu_command.c i/src/qemu/qemu_command.c
> index debaea491be8..55f19a27272c 100644
> --- c/src/qemu/qemu_command.c
> +++ i/src/qemu/qemu_command.c
> @@ -5238,8 +5238,7 @@ qemuBuildMemoryBackendStr(unsigned long long size,
>     }
>
>     /* If none of the following is requested... */
> -    if (!pagesize && !userNodeset && !memAccess &&
> -        !nodeSpecified && !nodemask && !force) {
> +    if (!pagesize && !nodemask && !memAccess && !nodeSpecified && !force)
> {
>         /* report back that using the new backend is not necessary
>          * to achieve the desired configuration */
>         ret = 1;
> --
>
> Basically I just used 'nodemask' instead of 'userNodeset'.  It works
> even without this diff because nodemask will always be set if
> userNodeset is set, it's just redundant to specify both.
>
> Martin
>
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>
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