Re: [Xen-devel] [PATCH 09 of 11] libxl, xl: enable automatic placement of guests on NUMA nodes

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-05-31 at 17:27 +0100, Dario Faggioli wrote:
> On Thu, 2012-05-31 at 16:02 +0100, Ian Jackson wrote:
> > Dario Faggioli writes ("[PATCH 09 of 11] libxl, xl: enable automatic 
> > placement of guests on NUMA nodes"):
> > > If a domain does not have a VCPU affinity, try to pin it automatically
> > > to some PCPUs. This is done taking into account the NUMA characteristics
> > > of the host: we look for a combination of host's NUMA nodes that has 
> > > enough
> > > free memoy for the new domain, and pin it to the VCPUs of those nodes.
> > > Smaller combinations are considered first, to avoid spreading the
> > > domain's memory among too many nodes.
> > 
> > Thanks for this.  Here are my comments:
> > 
> Thanks to you. :-)
> 
> > > +static void libxl_nodemap_rand_init(libxl_nodemap *nodemap)
> > > +{
> > > +    int i;
> > > +    nodemap->size = rand() % 16;
> > > +    nodemap->map = calloc(nodemap->size, sizeof(*nodemap->map));
> > > +    libxl_for_each_node(i, *nodemap) {
> > > +        if (rand() % 2)
> > > +            libxl_nodemap_set(nodemap, i);
> > > +        else
> > > +            libxl_nodemap_reset(nodemap, i);
> > > +    }
> > > +}
> > 
> > For your random number generation, please use nrand48, with a seed in
> > the libxl ctx.  (This means you'll need to take out the ctx lock.)
> > And provide a way to set the seed.
> > 
> Sounds reasonable, I'll look into this. As a side note, as I
> deliberately took inspiration from libxl_cpumap_rand_init() for this,
> should I apply what you just said to that function too?

This code is in gentest.py not libxl proper, it doesn't need a seed in
the ctx nor to use good random numbers, Ian J was mistakenly think this
was actual libxl functionality I think.

Ian.



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel