[libvirt] [PATCH] Balloon dom0 in libxl driver

[Jim Fehlig]

Daniel Veillard wrote:
> 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
>   

Sorry I didn't get to this before the release, but I haven't had much
time to work on libvirt recently.

ACK as well and I've pushed the patch now.  Thanks Markus.

Regards,
Jim