Re: [RFC] [PATCH] Power Managed memory base enabling

[David Rientjes <rientjes@google.com>]

On Tue, 6 Mar 2007, Mark Gross wrote:

> For the initial version of HW that can do this we are stuck with
> allocation based decisions where a complete solution needs page
> migration.
> 
> Yes, a sysfs interface is being looked at to export the control to a
> user mode daemon doing running some kind of policy manager, and if/when
> page migration happens it will be hooked up to this interface.
> 

Is do_migrate_pages() currently unsatisfactory for this?

> > > diff -urN -X linux-2.6.20-mm2/Documentation/dontdiff linux-2.6.20-mm2/mm/memory.c linux-2.6.20-mm2-monroe/mm/memory.c
> > > --- linux-2.6.20-mm2/mm/memory.c	2007-02-23 11:20:40.000000000 -0800
> > > +++ linux-2.6.20-mm2-monroe/mm/memory.c	2007-03-02 15:15:53.000000000 -0800
> > > @@ -2882,3 +2882,29 @@
> > >  	return buf - old_buf;
> > >  }
> > >  EXPORT_SYMBOL_GPL(access_process_vm);
> > > +
> > > +#ifdef __x86_64__
> > > +extern int __power_managed_memory_present(void);
> > > +extern int __power_managed_node(int srat_node);
> > > +extern int __find_closest_non_pm_node(int nodeid);
> > > +#else
> > > +inline int __power_managed_memory_present(void) { return 0};
> > > +inline int __power_managed_node(int srat_node) { return 0};
> > > +inline int __find_closest_non_pm_node(int nodeid) { return nodeid};
> > > +#endif
> > > +
> > > +int power_managed_memory_present(void)
> > > +{
> > > +	return __power_managed_memory_present();
> > > +}
> > > +
> > > +int power_managed_node(int srat_node)
> > > +{
> > > +	return __power_managed_node(srat_node);
> > > +}
> > > +
> > > +int find_closest_non_pm_node(int nodeid)
> > > +{
> > > +	return __find_closest_non_pm_node(nodeid);
> > > +}
> > > +
> > 
> > Probably should reconsider extern declarations in .c files.
> >
> 
> Yeah, but I couldn't think of a better place to put this code or how to
> make it portable to non x86_64 architectures.  Recommendations gratefully
> accepted.
> 

I would add this to include/asm-x86_64/topology.h:

	extern int __power_managed_memory_present(void);
	extern int __power_managed_node(int);
	extern int __find_closest_non_pm_node(int);
	#define power_managed_memory_present()	__power_managed_memory_present()
	#define power_managed_node(nid)		__power_managed_node(nid)
	#define find_closest_non_pm_node(nid)	__find_closest_non_pm_node(nid)

and then put the actual functions in arch/x86_64/numa.c.  Then something 
like this in include/linux/topology.h would probably suffice:

	#ifndef find_closest_non_pm_node
	#define find_closest_non_pm_node(nid)	do {} while(0)
	#endif

etc.

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