[virt-tools-list] [PATCHv2 2/2] Base mem statistics on virDomainMemoryStats if available.

[Cole Robinson]

On 12/18/2013 08:42 AM, Thorsten Behrens wrote:
> Attempt to query domain memory stats via virDomainMemoryStats.
> Fallback to old, possibly static virDomainGetInfo when that fails.
> ---
>  virtManager/domain.py | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/virtManager/domain.py b/virtManager/domain.py
> index c94ac57..11488f9 100644
> --- a/virtManager/domain.py
> +++ b/virtManager/domain.py
> @@ -245,6 +245,8 @@ class vmmDomain(vmmLibvirtObject):
>          self.remote_console_supported = False
>          self.title_supported = False
>  
> +        self._mem_stats_supported = True
> +
>          self._enable_net_poll = False
>          self._stats_net_supported = True
>          self._stats_net_skip = []
> @@ -1360,11 +1362,30 @@ class vmmDomain(vmmLibvirtObject):
>      ###################
>  
>      def _sample_mem_stats(self, info):
> +        # fallback - if the below fails, have at least the old
> +        # virDomainGetInfo data at hand
>          curmem = info[2]
> -        if not self.is_active():
> +        totalmem = self.maximum_memory()
> +        if (not self._mem_stats_supported or
> +            not self.is_active()):
>              curmem = 0

There's a few issues here. curmem should only be 0 if self.is_active(),
independent of the support check. So the GetInfo fallback doesn't work.

That said, I don't want the memory graph to mean different things if
memoryStats isn't supported, since that's just going to confuse people. So I
removed the GetInfo fallback.

We should find a way to make this case more clear in the UI, but that can come
later.

Pushed now, thanks.

- Cole

> +        else:
> +            # retrieve dynamic mem stats, if supported
> +            try:
> +                stats = self._backend.memoryStats()
> +                # did we get both required stat items back?
> +                if set(['actual', 'rss']).issubset(
> +                        set(stats.keys())):
> +                    curmem = stats['rss']
> +                    totalmem = stats['actual']
> +            except libvirt.libvirtError, err:
> +                if util.is_error_nosupport(err):
> +                    logging.debug("Mem stats not supported: %s", err)
> +                    self._mem_stats_supported = False
> +                else:
> +                    logging.error("Error reading mem stats: %s", err)
>  
> -        pcentCurrMem = curmem * 100.0 / self.maximum_memory()
> +        pcentCurrMem = curmem * 100.0 / totalmem
>          pcentCurrMem = max(0.0, min(pcentCurrMem, 100.0))
>  
>          return pcentCurrMem, curmem
>