[libvirt] [PATCH 16/35] qemu: Add helper to update domain balloon size and refactor usage places

[Ján Tomko]

On Fri, May 29, 2015 at 03:33:37PM +0200, Peter Krempa wrote:
> When qemu does not support the balloon event the current memory size
> needs to be queried. Since there are two places that implement the same
> logic, split it out into a function and reuse.
> ---
>  src/qemu/qemu_domain.c | 64 ++++++++++++++++++++++++++++++++++++++
>  src/qemu/qemu_domain.h |  3 ++
>  src/qemu/qemu_driver.c | 84 +++++---------------------------------------------
>  3 files changed, 75 insertions(+), 76 deletions(-)
> 
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index db8554b..661181f 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -3182,3 +3182,67 @@ qemuDomainMachineIsI440FX(const virDomainDef *def)
>              STRPREFIX(def->os.machine, "pc-i440") ||
>              STRPREFIX(def->os.machine, "rhel"));
>  }
> +
> +
> +/**
> + * qemuDomainUpdateCurrentMemorySize:
> + *
> + * Updates the current balloon size from the monitor if necessary. In case when
> + * the balloon is not present for the domain, the function recalculates the
> + * maximum size to reflect possible changes.
> + *
> + * Returns 0 on success and updates vm->def->mem.cur_balloon if necessary, -1 on
> + * error and reports libvirt error.
> + */
> +int
> +qemuDomainUpdateCurrentMemorySize(virQEMUDriverPtr driver,
> +                                  virDomainObjPtr vm)
> +{
> +    qemuDomainObjPrivatePtr priv = vm->privateData;
> +    unsigned long long balloon;
> +    int ret = -1;
> +
> +    /* inactive domain doesn't need size update */
> +    if (!virDomainObjIsActive(vm))
> +        return 0;
> +
> +    /* if no balloning is available, the current size equals to the current
> +     * full memory size */
> +    if (!vm->def->memballoon ||
> +        vm->def->memballoon->model == VIR_DOMAIN_MEMBALLOON_MODEL_NONE) {
> +        vm->def->mem.cur_balloon = virDomainDefGetMemoryActual(vm->def);
> +        return 0;
> +    }
> +
> +    /* current size is always automagically updated via the event */
> +    if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BALLOON_EVENT))
> +        return 0;
> +
> +    /* here we need to ask the monitor */
> +
> +    /* Don't delay if someone's using the monitor, just use existing most
> +     * recent data instead */
> +    if (qemuDomainJobAllowed(priv, QEMU_JOB_QUERY)) {
> +        if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_QUERY) < 0)
> +            return -1;
> +
> +        if (!virDomainObjIsActive(vm)) {
> +            virReportError(VIR_ERR_OPERATION_INVALID, "%s",
> +                           _("domain is not running"));
> +            goto endjob;
> +        }
> +
> +        qemuDomainObjEnterMonitor(driver, vm);
> +        ret = qemuMonitorGetBalloonInfo(priv->mon, &balloon);
> +        if (qemuDomainObjExitMonitor(driver, vm) < 0)
> +            ret = -1;
> +
> + endjob:
> +        qemuDomainObjEndJob(driver, vm);
> +
> +        if (ret < 0)
> +            return -1;

ACK if you actually use the 'balloon' value to update cur_balloon here.

Jan

> +    }
> +
> +    return 0;
> +}
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