[libvirt] [PATCHv2 1/2] qemu: reflect any memory rounding back to xml

[Osier Yang]

On 03/31/2012 02:47 PM, Osier Yang wrote:
> On 03/30/2012 11:56 PM, Eric Blake wrote:
>> If we round up a user's memory request, we should update the XML
>> to reflect the actual value in use by the VM, rather than giving
>> an artificially small value back to the user.
>>
>> * src/qemu/qemu_command.c (qemuBuildNumaArgStr)
>> (qemuBuildCommandLine): Reflect rounding back to XML.
>> ---
>> src/qemu/qemu_command.c | 11 +++++++----
>> 1 files changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
>> index 3d2bb6b..8f6471b 100644
>> --- a/src/qemu/qemu_command.c
>> +++ b/src/qemu/qemu_command.c
>> @@ -3916,8 +3916,9 @@ qemuBuildNumaArgStr(const virDomainDefPtr def,
>> virCommandPtr cmd)
>> virBufferAsprintf(&buf, "node,nodeid=%d", def->cpu->cells[i].cellid);
>> virBufferAddLit(&buf, ",cpus=");
>> qemuBuildNumaCPUArgStr(def->cpu->cells[i].cpumask,&buf);
>> - virBufferAsprintf(&buf, "mem=%d",
>> - VIR_DIV_UP(def->cpu->cells[i].mem, 1024));
>> + def->cpu->cells[i].mem = VIR_DIV_UP(def->cpu->cells[i].mem,
>> + 1024) * 1024;
>> + virBufferAsprintf(&buf, "mem=%d", def->cpu->cells[i].mem / 1024);
>>
>> if (virBufferError(&buf))
>> goto error;
>> @@ -4061,10 +4062,12 @@ qemuBuildCommandLine(virConnectPtr conn,
>>
>> /* Set '-m MB' based on maxmem, because the lower 'memory' limit
>> * is set post-startup using the balloon driver. If balloon driver
>> - * is not supported, then they're out of luck anyway
>> + * is not supported, then they're out of luck anyway. Update the
>> + * XML to reflect our rounding.
>> */
>> virCommandAddArg(cmd, "-m");
>> - virCommandAddArgFormat(cmd, "%llu", VIR_DIV_UP(def->mem.max_balloon,
>> 1024));
>> + def->mem.max_balloon = VIR_DIV_UP(def->mem.max_balloon, 1024) * 1024;
>> + virCommandAddArgFormat(cmd, "%llu", def->mem.max_balloon / 1024);
>> if (def->mem.hugepage_backed) {
>> if (!driver->hugetlbfs_mount) {
>> qemuReportError(VIR_ERR_INTERNAL_ERROR,
>
> It makes sense to reflect the real memory used in qemu command
> line back to domain conf, but IMHO we need the documentations to
> declare that the these memory stuffs mighted be rounded up,
> otherwise I guess bugs will come by confused users.
>

<snip>
     However, the value will be rounded up to the nearest kibibyte by 
libvirt, and may be further rounded to the granularity supported by the 
hypervisor. Some hypervisors also enforce a minimum, such as 4000KiB. 
unit since 0.9.11
currentMemory
</snip>

Forgot about it, we already have documentation for it, :=)

ACK