Messages in this thread Patch in this message | | | Subject | [RFC][PATCH 4/4] unify both copies of build_zonelists() | From | Dave Hansen <> | Date | Tue, 20 Sep 2005 10:23:12 -0700 |
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Once the last three patches are applied, find_next_best_node() has three properties which make its behavior identical to the way that the !NUMA build_zonelists() functions.
First, this code from build_zonelists():
j = 0; k = zone_index_to_type(i); j = build_zonelists_node(pgdat, zonelist, j, k);
makes sure that the node for which we're building a zonelist is first in that zone's list. That is functionally equivalent to this code in find_next_best_node():
/* Use the local node if we haven't already */ if (!node_isset(node, *used_node_mask)) { best_node = node; break; }
Next, the !NUMA build_zonelists() starts at the local node, and searches all larger-numbered nodes, then searches all nodes from 0 back up to the local node:
for (node = local_node + 1; node < MAX_NUMNODES; node++) { if (!node_online(node)) continue; j = build_zonelists_node(NODE_DATA(node), zonelist, j, k); } for (node = 0; node < local_node; node++) { if (!node_online(node)) continue; j = build_zonelists_node(NODE_DATA(node), zonelist, j, k); }
Instead of doing this explicitly, find_next_best_node() uses a modulo but, again, the behavior is the same:
/* Start from local node */ n = (node+i) % num_online_nodes();
Lastly, "val" will be equivalent for each find_next_best_node() loop iteration because: 1. node_distance() always return the same value (except when node == n, but that never happens because of the local node check above) 2. The 'if (!cpus_empty(tmp))' check will never succeed because the cpumask for !NUMA is cpu_online_map, which is never empty. 3. (MAX_NODE_LOAD*MAX_NUMNODES) == 1 4. get_node_load() == 0
Signed-off-by: Dave Hansen <haveblue@us.ibm.com> ---
memhotplug-dave/mm/page_alloc.c | 41 ---------------------------------------- 1 files changed, 41 deletions(-)
diff -puN mm/page_alloc.c~B1.3-build_zonelists_unification mm/page_alloc.c --- memhotplug/mm/page_alloc.c~B1.3-build_zonelists_unification 2005-09-14 09:32:39.000000000 -0700 +++ memhotplug-dave/mm/page_alloc.c 2005-09-14 09:32:39.000000000 -0700 @@ -1577,47 +1577,6 @@ static void __init build_zonelists(pg_da } } -#else /* CONFIG_NUMA */ - -static void __init build_zonelists(pg_data_t *pgdat) -{ - int i, j, k, node, local_node; - - local_node = pgdat->node_id; - for (i = 0; i < GFP_ZONETYPES; i++) { - struct zonelist *zonelist; - - zonelist = pgdat->node_zonelists + i; - - j = 0; - k = zone_index_to_type(i); - - j = build_zonelists_node(pgdat, zonelist, j, k); - /* - * Now we build the zonelist so that it contains the zones - * of all the other nodes. - * We don't want to pressure a particular node, so when - * building the zones for node N, we make sure that the - * zones coming right after the local ones are those from - * node N+1 (modulo N) - */ - for (node = local_node + 1; node < MAX_NUMNODES; node++) { - if (!node_online(node)) - continue; - j = build_zonelists_node(NODE_DATA(node), zonelist, j, k); - } - for (node = 0; node < local_node; node++) { - if (!node_online(node)) - continue; - j = build_zonelists_node(NODE_DATA(node), zonelist, j, k); - } - - zonelist->zones[j] = NULL; - } -} - -#endif /* CONFIG_NUMA */ - void __init build_all_zonelists(void) { int i; diff -L b.txt -puN /dev/null /dev/null _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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