On Tue, 18 Sep 2012 00:03:57 -0700 (PDT) David Rientjes <[email protected]> wrote:
> RECLAIM_DISTANCE represents the distance between nodes at which it is > deemed too costly to allocate from; it's preferred to try to reclaim from > a local zone before falling back to allocating on a remote node with such > a distance. > > To do this, zone_reclaim_mode is set if the distance between any two > nodes on the system is greather than this distance. This, however, ends > up causing the page allocator to reclaim from every zone regardless of > its affinity. > > What we really want is to reclaim only from zones that are closer than > RECLAIM_DISTANCE. This patch adds a nodemask to each node that > represents the set of nodes that are within this distance. During the > zone iteration, if the bit for a zone's node is set for the local node, > then reclaim is attempted; otherwise, the zone is skipped. Is this a theoretical thing, or does the patch have real observable effects? This change makes it more important that the arch code implements node_distance() accurately (wrt RECLAIM_DISTANCE), yes? I wonder how much code screwed that up, and what the effects of such a screwup would be, and how arch maintainers would go about detecting then fixing such an error? -- 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/
