[libvirt] [PATCH] Balloon dom0 in libxl driver

[Daniel Veillard]

On Wed, May 04, 2011 at 12:17:06PM +0200, Markus Groß wrote:
> Creating a domU on a freshly booted dom0 does not work,
> because the libxl driver does not allocate memory for the domU.
> After creating a domain with xl libvirt is able to create domains too.
> This patch reserves enough memory for the domU first.
> ---
>  src/libxl/libxl_driver.c |   48 ++++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 46 insertions(+), 2 deletions(-)
> 
> diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
> index 247d78e..d4ca025 100644
> --- a/src/libxl/libxl_driver.c
> +++ b/src/libxl/libxl_driver.c
> @@ -498,6 +498,46 @@ cleanup:
>      return ret;
>  }
>  
> +static int
> +libxlFreeMem(libxlDomainObjPrivatePtr priv, libxl_domain_config *d_config)
> +{
> +    uint32_t needed_mem;
> +    uint32_t free_mem;
> +    int i;
> +    int ret = -1;
> +    int tries = 3;
> +    int wait_secs = 10;
> +
> +    if ((ret = libxl_domain_need_memory(&priv->ctx, &d_config->b_info,
> +                                        &d_config->dm_info,
> +                                        &needed_mem)) >= 0) {
> +        for (i = 0; i < tries; ++i) {
> +            if ((ret = libxl_get_free_memory(&priv->ctx, &free_mem)) < 0)
> +                break;
> +
> +            if (free_mem >= needed_mem) {
> +                ret = 0;
> +                break;
> +            }
> +
> +            if ((ret = libxl_set_memory_target(&priv->ctx, 0,
> +                                               free_mem - needed_mem,
> +                                               /* relative */ 1, 0)) < 0)
> +                break;
> +
> +            ret = libxl_wait_for_free_memory(&priv->ctx, 0, needed_mem,
> +                                             wait_secs);
> +            if (ret == 0 || ret != ERROR_NOMEM)
> +                break;
> +
> +            if ((ret = libxl_wait_for_memory_target(&priv->ctx, 0, 1)) < 0)
> +                break;
> +        }
> +    }
> +
> +    return ret;
> +}
> +
>  /*
>   * Start a domain through libxenlight.
>   *
> @@ -521,8 +561,12 @@ libxlVmStart(libxlDriverPrivatePtr driver,
>      if (libxlBuildDomainConfig(driver, def, &d_config) < 0 )
>          return -1;
>  
> -    //TODO: Balloon dom0 ??
> -    //ret = freemem(&d_config->b_info, &d_config->dm_info);
> +    if (libxlFreeMem(priv, &d_config) < 0) {
> +        libxlError(VIR_ERR_INTERNAL_ERROR,
> +                   _("libxenlight failed to get free memory for domain '%s'"),
> +                   d_config.c_info.name);
> +        goto error;
> +    }
>  
>      ret = libxl_domain_create_new(&priv->ctx, &d_config,
>                                    NULL, &child_console_pid, &domid);

  That looks okay to me. My main question is if it's critical enough
  that we should push this in 0.9.1,

    ACK, but I don't know if it should be commited immediately

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel at veillard.com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/