[libvirt] [PATCH] qemu: do not ask for balloon information if not used

[Daniel P. Berrange]

On Thu, Aug 12, 2010 at 02:07:41PM +0200, Daniel Veillard wrote:
>  Basically a followup of the previous patch about balloon desactivation
> if desactivated, to not ask for balloon information to qemu as we will
> just get an error back.
>  This can make a huge difference in the time needed for domain
> information or list when a machine is loaded, and balloon has been
> desactivated in the guests.
> 
> Note that the patch does a check in the GetDomainInfo function, to avoid
> checking for job, getting a job, getting the monitor lock and cleaning
> back which would be added operations if I had done this one level
> down in qemuMonitorGetBalloonInfo()
> The qemudDomainDumpXML() function also call qemuMonitorGetBalloonInfo()
> so maybe the check should be duplicated there, I left that out of the
> patch for now as this is an operation which sounds less time critical.
> Or maybe the test should be added to qemuMonitorGetBalloonInfo() too
> since it's exported from src/qemu/qemu_monitor.h and may end up being
> used from other places in the future,

Nah, putting it in qemu_driver is the correct place. The qemu_monitor.h
files are designed to not have any awareness of the virDomainDef
structures - just simple commaands to talk to the monitor. We should
add the same to DumpXML as you say.


> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index e4f47d4..deb8b02 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -4938,7 +4938,11 @@ static int qemudDomainGetInfo(virDomainPtr dom,
>  
>      if (virDomainObjIsActive(vm)) {
>          qemuDomainObjPrivatePtr priv = vm->privateData;
> -        if (!priv->jobActive) {
> +
> +        if ((vm->def->memballoon != NULL) &&
> +            (vm->def->memballoon->model == VIR_DOMAIN_MEMBALLOON_MODEL_NONE)) {
> +            info->memory = vm->def->maxmem;
> +        } else if (!priv->jobActive) {
>              if (qemuDomainObjBeginJob(vm) < 0)
>                  goto cleanup;
>  

Daniel
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