On Tue, 11 Sep 2007 22:31:27 +0100 (IST) Mel Gorman <[EMAIL PROTECTED]> wrote:
> Using two zonelists per node requires very frequent use of zone_idx(). This > is costly as it involves a lookup of another structure and a substraction > operation. As struct zone is always word aligned and normally cache-line > aligned, the pointer values have a number of 0's at the least significant > bits of the address. > > This patch embeds the zone_id of a zone in the zonelist->zones pointers. > The real zone pointer is retrieved using the zonelist_zone() helper function. > The ID of the zone is found using zonelist_zone_idx(). To avoid accidental > references, the zones field is renamed to _zones and the type changed to > unsigned long. > At first, I welcome this patch. thanks!. A comment after reading all is, how about defining zonelist as following instead of encoding in pointer ? == struct zone_pointer { struct zone *zone; int node_id; int zone_idx; }; struct zonelist { struct zone_pointer _zones[MAX_ZONES_PER_ZONELIST + 1]; }; #define zonelist_zone(zl) (zl)->zone #define zonelist_zone_idx(zl) (zl)->zone_idx #ifdef CONFIG_NUMA #define zonelist_zone_nid(zl) (zl)->node_id #else #define zonelist_zone_nid(zl, i) (0) == If we really want to avoid unnecessary access to "zone" while walking zonelist, above may do something good. Cons is this makes sizeof zonlist bigger. Thanks, -Kame - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/