On Tue, Feb 23, 2016 at 10:13:18AM -0800, Johannes Weiner wrote:

On Tue, Feb 23, 2016 at 03:04:26PM +0000, Mel Gorman wrote:

quoted

VM statistic counters for reclaim decisions are zone-based. If the kernel
is to reclaim on a per-node basis then we need to track per-node statistics
but there is no infrastructure for that. The most notable change is that
the old node_page_state is renamed to sum_zone_node_page_state.  The new
node_page_state takes a pglist_data and uses per-node stats but none exist
yet. There is some renaming such as vm_stat to vm_zone_stat and the addition
of vm_node_stat and the renaming of mod_state to mod_zone_state. Otherwise,
this is mostly a mechanical patch with no functional change. There is a
lot of similarity between the node and zone helpers which is unfortunate
but there was no obvious way of reusing the code and maintaining type safety.

Signed-off-by: Mel Gorman <redacted>

Hopefully we can eventually ditch /proc/zoneinfo in favor of a
/proc/nodeinfo and get rid of the per-zone stats accounting.

It may not be possible to ditch /proc/zoneinfo entirely but a /proc/nodeinfo
would make sense. It may interfere with userspace that's aware of kernel
internals but that may be manageable.

In general, this patch looks good to me.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Thanks.

Only one thing I noticed:

quoted

@@ -349,12 +349,14 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 	shadow_nodes = list_lru_shrink_count(&workingset_shadow_nodes, sc);
 	local_irq_enable();
 
-	if (memcg_kmem_enabled())
+	if (memcg_kmem_enabled()) {
 		pages = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid,
 						     LRU_ALL_FILE);
-	else
-		pages = node_page_state(sc->nid, NR_ACTIVE_FILE) +
-			node_page_state(sc->nid, NR_INACTIVE_FILE);
+	} else {
+		pg_data_t *pgdat = NODE_DATA(sc->nid);
+		pages = node_page_state(pgdat, NR_ACTIVE_FILE) +
+			node_page_state(pgdat, NR_INACTIVE_FILE);
+	}

That should also be sum_zone_node_page_state, right? These are not
valid node items (yet).

Yep, not for another two patches. Fixed now.

-- 
Mel Gorman
SUSE Labs

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