Re: [Qemu-devel] [PATCH 5/5] balloon: Use only 'pc-dimm' type dimm for ballooning

[Vladimir Sementsov-Ogievskiy]

On 05.02.2016 15:58, Igor Mammedov wrote:
> On Fri,  5 Feb 2016 11:19:01 +0300
> Vladimir Sementsov-Ogievskiy <address@hidden> wrote:
>
> > For now there are only two dimm's: pc-dimm and nvdimm. This patch is
> > actually needed to disable ballooning on nvdimm. But, to avoid future
> > bugs, instead of disallowing nvdimm, we allow only pc-dimm. So, if
> > someone adds new dimm which should be balloon-able, then this ability
> > should be explicitly specified here.
> >
> > Why ballooning for nvdimm should be disabled for now:
> >
> > NVDIMM for now is planned to use as a backing store for DAX filesystem
> > in the guest and thus this memory is excluded from guest memory
> > management and LRUs.
> >
> > In this case libvirt running QEMU along with configured balloon almost
> > immediately inflates balloon and effectively kill the guest as
> > qemu counts nvdimm as part of the ram.
> >
> > Counting dimm devices as part of the ram for ballooning was started from
> > commit 463756d03:
> >   virtio-balloon: Fix balloon not working correctly when hotplug memory
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> > Signed-off-by: Denis V. Lunev <address@hidden>
> > ---
> >   hw/virtio/virtio-balloon.c | 6 +++++-
> >   1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> > index b9c1964..0415e07 100644
> > --- a/hw/virtio/virtio-balloon.c
> > +++ b/hw/virtio/virtio-balloon.c
> > @@ -18,6 +18,7 @@
> >   #include "qemu-common.h"
> >   #include "hw/virtio/virtio.h"
> >   #include "hw/i386/pc.h"
> > +#include "hw/mem/nvdimm.h"
> Is this include still needed?

Yes, for TYPE_PC_DIMM

> >   #include "cpu.h"
> >   #include "sysemu/balloon.h"
> >   #include "hw/virtio/virtio-balloon.h"
> > @@ -302,7 +303,10 @@ static ram_addr_t get_current_ram_size(void)
> >       pc_dimm_build_list(qdev_get_machine(), &list);
> >       for (item = list; item; item = g_slist_next(item)) {
> >           PCDIMMDevice *dimm = item->data;
> > -        size += object_property_get_int(OBJECT(dimm), PC_DIMM_SIZE_PROP, NULL);
> > +        if (!strcmp(object_get_typename(OBJECT(dimm)), TYPE_PC_DIMM)) {
> > +            size += object_property_get_int(OBJECT(dimm), PC_DIMM_SIZE_PROP,
> > +                                            NULL);
> > +        }
> >       }
> >       g_slist_free(list);
> >   


--
Best regards,
Vladimir