On Mon, Sep 19, 2011 at 04:29:55PM +0200, Michal Hocko wrote:

On Mon 12-09-11 12:57:20, Johannes Weiner wrote:

quoted

Memory cgroup hierarchies are currently handled completely outside of
the traditional reclaim code, which is invoked with a single memory
cgroup as an argument for the whole call stack.

Subsequent patches will switch this code to do hierarchical reclaim,
so there needs to be a distinction between a) the memory cgroup that
is triggering reclaim due to hitting its limit and b) the memory
cgroup that is being scanned as a child of a).

This patch introduces a struct mem_cgroup_zone that contains the
combination of the memory cgroup and the zone being scanned, which is
then passed down the stack instead of the zone argument.

Signed-off-by: Johannes Weiner <redacted>

Looks good to me. Some minor comments bellow
Anyways:
Reviewed-by: Michal Hocko <redacted>

Thanks!

quoted

@@ -1853,13 +1865,13 @@ static int vmscan_swappiness(struct scan_control *sc)
  *
  * nr[0] = anon pages to scan; nr[1] = file pages to scan
  */
-static void get_scan_count(struct zone *zone, struct scan_control *sc,
-					unsigned long *nr, int priority)
+static void get_scan_count(struct mem_cgroup_zone *mz, struct scan_control *sc,
+			   unsigned long *nr, int priority)
 {
 	unsigned long anon, file, free;
 	unsigned long anon_prio, file_prio;
 	unsigned long ap, fp;
-	struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
+	struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
 	u64 fraction[2], denominator;
 	enum lru_list l;
 	int noswap = 0;

You can save some patch lines by:
	struct zone *zone = mz->zone;
and not doing zone => mz->zone changes that follow.

Actually, I really hate that I had to do that local zone variable in
other places.  I only did it where it's used so often that it would
have changed every other line.  If you insist, I'll change it, but I
would prefer to avoid it when possible.

quoted

@@ -2390,6 +2413,18 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
 }
 #endif
 
+static void age_active_anon(struct zone *zone, struct scan_control *sc,
+			    int priority)
+{
+	struct mem_cgroup_zone mz = {
+		.mem_cgroup = NULL,
+		.zone = zone,
+	};
+
+	if (inactive_anon_is_low(&mz))
+		shrink_active_list(SWAP_CLUSTER_MAX, &mz, sc, priority, 0);
+}
+

I do not like this very much because we are using a similar construct in
shrink_mem_cgroup_zone so we are duplicating that code. 
What about adding age_mem_cgroup_active_anon (something like shrink_zone).

I am not sure I follow and I don't see what could be shared between
the zone shrinking and this as there are different exit conditions to
the hierarchy walk.  Can you elaborate?

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>