Messages in this thread Patch in this message | | | Subject | Re: [PATCH 5/6] Have zonelist contains structs with both a zone pointer and zone_idx | From | Lee Schermerhorn <> | Date | Wed, 21 Nov 2007 13:38:46 -0500 |
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On Wed, 2007-11-21 at 13:18 -0500, Lee Schermerhorn wrote: > On Wed, 2007-11-21 at 13:12 -0500, Lee Schermerhorn wrote: > > Mel: > > > > Are the comparisons noted below correct--i.e., '>' rather than '<'? I'm > > trying to understand how this matches the comments and code. Doesn't > > look right to me, but I could be missing something. > > > > Lee > > Never mind... I get it now. I was confusing zone ids with node ids. >
However... [possibly another stupid question]
Don't the loops in {first|next}_zones_zonelist() depend on the zonelists being in "zone order" as opposed to "node order". If the nodelists are in node order, the lower zones can be interspersed with the upper zones, I think. Looks like this would terminate the loops as soon as we hit a lower zone, even tho' we might not have visited all of the nodes represented in the zonelist.
Again, I could be missing some fine point of zonerefs that handles this condition, but I can't see it.
Lee
> Lee > > > > On Wed, 2007-11-21 at 00:40 +0000, Mel Gorman wrote: > > > Filtering zonelists requires very frequent use of zone_idx(). This is costly > > > as it involves a lookup of another structure and a substraction operation. As > > > the zone_idx is often required, it should be quickly accessible. The node > > > idx could also be stored here if it was found that accessing zone->node is > > > significant which may be the case on workloads where nodemasks are heavily > > > used. > > > > > > This patch introduces a struct zoneref to store a zone pointer and a zone > > > index. The zonelist then consists of an array of these struct zonerefs which > > > are looked up as necessary. Helpers are given for accessing the zone index > > > as well as the node index. > > > > > > [kamezawa.hiroyu@jp.fujitsu.com: Suggested struct zoneref instead of embedding information in pointers] > > > Signed-off-by: Mel Gorman <mel@csn.ul.ie> > > > Acked-by: Christoph Lameter <clameter@sgi.com> > > > Acked-by: David Rientjes <rientjes@google.com> > > > --- > > > > > > arch/parisc/mm/init.c | 2 - > > > fs/buffer.c | 6 ++-- > > > include/linux/mmzone.h | 64 ++++++++++++++++++++++++++++++++++++------ > > > include/linux/oom.h | 4 +- > > > kernel/cpuset.c | 4 +- > > > mm/hugetlb.c | 3 +- > > > mm/mempolicy.c | 36 ++++++++++++++---------- > > > mm/oom_kill.c | 45 ++++++++++++++---------------- > > > mm/page_alloc.c | 66 ++++++++++++++++++++++++-------------------- > > > mm/slab.c | 2 - > > > mm/slub.c | 2 - > > > mm/vmscan.c | 6 ++-- > > > 12 files changed, 149 insertions(+), 91 deletions(-) > > > > > <snip> > > > diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.24-rc2-mm1-010_use_two_zonelists/include/linux/mmzone.h linux-2.6.24-rc2-mm1-020_zoneid_zonelist/include/linux/mmzone.h > > > --- linux-2.6.24-rc2-mm1-010_use_two_zonelists/include/linux/mmzone.h 2007-11-20 23:27:04.000000000 +0000 > > > +++ linux-2.6.24-rc2-mm1-020_zoneid_zonelist/include/linux/mmzone.h 2007-11-20 23:27:34.000000000 +0000 > > > @@ -469,6 +469,15 @@ struct zonelist_cache; > > > #endif > > > > > > /* > > > + * This struct contains information about a zone in a zonelist. It is stored > > > + * here to avoid dereferences into large structures and lookups of tables > > > + */ > > > +struct zoneref { > > > + struct zone *zone; /* Pointer to actual zone */ > > > + int zone_idx; /* zone_idx(zoneref->zone) */ > > > +}; > > > + > > > +/* > > > * One allocation request operates on a zonelist. A zonelist > > > * is a list of zones, the first one is the 'goal' of the > > > * allocation, the other zones are fallback zones, in decreasing > > > @@ -476,11 +485,18 @@ struct zonelist_cache; > > > * > > > * If zlcache_ptr is not NULL, then it is just the address of zlcache, > > > * as explained above. If zlcache_ptr is NULL, there is no zlcache. > > > + * * > > > + * To speed the reading of the zonelist, the zonerefs contain the zone index > > > + * of the entry being read. Helper functions to access information given > > > + * a struct zoneref are > > > + * > > > + * zonelist_zone() - Return the struct zone * for an entry in _zonerefs > > > + * zonelist_zone_idx() - Return the index of the zone for an entry > > > + * zonelist_node_idx() - Return the index of the node for an entry > > > */ > > > - > > > struct zonelist { > > > struct zonelist_cache *zlcache_ptr; // NULL or &zlcache > > > - struct zone *zones[MAX_ZONES_PER_ZONELIST + 1]; // NULL delimited > > > + struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1]; > > > #ifdef CONFIG_NUMA > > > struct zonelist_cache zlcache; // optional ... > > > #endif > > > @@ -713,26 +729,52 @@ extern struct zone *next_zone(struct zon > > > zone; \ > > > zone = next_zone(zone)) > > > > > > +static inline struct zone *zonelist_zone(struct zoneref *zoneref) > > > +{ > > > + return zoneref->zone; > > > +} > > > + > > > +static inline int zonelist_zone_idx(struct zoneref *zoneref) > > > +{ > > > + return zoneref->zone_idx; > > > +} > > > + > > > +static inline int zonelist_node_idx(struct zoneref *zoneref) > > > +{ > > > +#ifdef CONFIG_NUMA > > > + /* zone_to_nid not available in this context */ > > > + return zoneref->zone->node; > > > +#else > > > + return 0; > > > +#endif /* CONFIG_NUMA */ > > > +} > > > + > > > +static inline void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref) > > > +{ > > > + zoneref->zone = zone; > > > + zoneref->zone_idx = zone_idx(zone); > > > +} > > > + > > > /* Returns the first zone at or below highest_zoneidx in a zonelist */ > > > -static inline struct zone **first_zones_zonelist(struct zonelist *zonelist, > > > +static inline struct zoneref *first_zones_zonelist(struct zonelist *zonelist, > > > enum zone_type highest_zoneidx) > > > { > > > - struct zone **z; > > > + struct zoneref *z; > > > > > > /* Find the first suitable zone to use for the allocation */ > > > - z = zonelist->zones; > > > - while (*z && zone_idx(*z) > highest_zoneidx) > > > + z = zonelist->_zonerefs; > > > + while (zonelist_zone_idx(z) > highest_zoneidx) > > !!! HERE: ^ > > > z++; > > > > > > return z; > > > } > > > > > > /* Returns the next zone at or below highest_zoneidx in a zonelist */ > > > -static inline struct zone **next_zones_zonelist(struct zone **z, > > > +static inline struct zoneref *next_zones_zonelist(struct zoneref *z, > > > enum zone_type highest_zoneidx) > > > { > > > /* Find the next suitable zone to use for the allocation */ > > > - while (*z && zone_idx(*z) > highest_zoneidx) > > > + while (zonelist_zone_idx(z) > highest_zoneidx) > > !!! and HERE: ^ > > > z++; > > > > > > return z; > > > @@ -748,9 +790,11 @@ static inline struct zone **next_zones_z > > > * This iterator iterates though all zones at or below a given zone index. > > > */ > > > #define for_each_zone_zonelist(zone, z, zlist, highidx) \ > > > - for (z = first_zones_zonelist(zlist, highidx), zone = *z++; \ > > > + for (z = first_zones_zonelist(zlist, highidx), \ > > > + zone = zonelist_zone(z++); \ > > > zone; \ > > > - z = next_zones_zonelist(z, highidx), zone = *z++) > > > + z = next_zones_zonelist(z, highidx), \ > > > + zone = zonelist_zone(z++)) > > > > > > #ifdef CONFIG_SPARSEMEM > > > #include <asm/sparsemem.h> > > <snip>
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