Re: [Xen-devel] [libvirt] [PATCH RESENT 04/12] libxl: populate xenstore memory entries at startup

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 11 Apr 2013, Ian Campbell wrote:
> On Thu, 2013-04-11 at 05:09 +0100, Jim Fehlig wrote:
> > > +    /* This will fill xenstore info about free and dom0 memory - if 
> > > missing,
> > > +     * should be called before starting first domain */
> > > +    if (libxl_get_free_memory(libxl_driver->ctx, &free_mem)) {
> > > +        VIR_ERROR(_("cannot get free memory info"));
> > > +        goto error;
> > > +    }
> > >   
> > 
> > Should failure of libxl_get_free_memory() really be fatal and prevent
> > the driver from loading?
> 
> I'm not sure it is intended to be called like this...
> 
> I think it is intended to be called as part of starting every domain, to
> check if there is enough free memory for that domain, rather than
> calling it once at start of day.

Actually libxl_get_free_memory is just meant to return to total amount
of free memory in the system. Can be called at any time.
As a side effect of libxl_get_free_memory, freemem-slack will be
written to xenstore if it wasn't before.

I think that it is OK to call it as Marek did in this patch, even though
might be nicer if we had a proper "libxl_initialize_memory_accounting"
function.

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