Re: [Qemu-devel] [PATCH 3/3] balloon: don't use NVDIMM for ballooning

[Markus Armbruster]

Eric Blake <address@hidden> writes:

> On 01/27/2016 11:51 PM, Vladimir Sementsov-Ogievskiy wrote:
>> 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>
>> CC: Stefan Hajnoczi <address@hidden>
>> CC: Xiao Guangrong <address@hidden>
>> CC: "Michael S. Tsirkin" <address@hidden>
>> CC: Igor Mammedov <address@hidden>
>> CC: Eric Blake <address@hidden>
>> CC: Markus Armbruster <address@hidden>
>> ---
>
>> @@ -308,7 +309,9 @@ static ram_addr_t get_current_ram_size(void)
>>          if (value) {
>>              switch (value->type) {
>>              case MEMORY_DEVICE_INFO_KIND_DIMM:
>> -                size += value->u.dimm->size;
>> +                if (strcmp(value->u.dimm->type, TYPE_NVDIMM)) {
>
> If you fix 2/3 to use a QAPI enum, then this will be an integer compare
> instead of a strcmp().

Another option is to add a flag to the subtypes of TYPE_PC_DIMM, set it
for the subtypes that should be counted here, and accumulate the sizes
of devices where the flag is set.  Requires iterating directly over the
devices here (like qmp_pc_dimm_device_list() does under the hood) rather
than the MemoryDeviceInfoList returned by qmp_pc_dimm_device_list(),