Re: [PATCH 3/4] Embed zone_id information within the zonelist->zones pointer

Mel Gorman
2007-08-09T23:33:01Z

On (09/08/07 14:37), Christoph Lameter didst pronounce:
> On Thu, 9 Aug 2007, Mel Gorman wrote:
>
> > }
> >
> > +#if defined(CONFIG_SMP) && INTERNODE_CACHE_SHIFT > ZONES_SHIFT
>
> Is this necessary? ZONES_SHIFT is always <= 2 so it will work with
> any pointer. Why disable this for UP?
>

Caution in case the number of zones increases. There was no guarantee of
zone alignment. It's the same reason I have a BUG_ON in the encode
function so that if we don't catch problems at compile-time, it'll go
BANG in a nice predictable fashion.

> > --- linux-2.6.23-rc1-mm2-010_use_zonelist/mm/vmstat.c 2007-08-07 14:45:11.000000000 +0100
> > +++ linux-2.6.23-rc1-mm2-015_zoneid_zonelist/mm/vmstat.c 2007-08-09 15:52:12.000000000 +0100
> > @@ -365,11 +365,11 @@ void refresh_cpu_vm_stats(int cpu)
> > */
> > void zone_statistics(struct zonelist *zonelist, struct zone *z)
> > {
> > - if (z->zone_pgdat == zonelist->zones[0]->zone_pgdat) {
> > + if (z->zone_pgdat == zonelist_zone(zonelist->_zones[0])->zone_pgdat) {
> > __inc_zone_state(z, NUMA_HIT);
> > } else {
> > __inc_zone_state(z, NUMA_MISS);
> > - __inc_zone_state(zonelist->zones[0], NUMA_FOREIGN);
> > + __inc_zone_state(zonelist_zone(zonelist->_zones[0]), NUMA_FOREIGN);
> > }
> > if (z->node == numa_node_id())
> > __inc_zone_state(z, NUMA_LOCAL);
>
> Hmmmm. I hope the compiler does subexpression optimization on
>
> zonelist_zone(zonelist->_zones[0])
>

I'll check

> Acked-by: Christoph Lameter <clameter@sgi.com>
>

--
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Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab