On 06/21/2016 04:15 PM, Mel Gorman wrote:
This patch makes reclaim decisions on a per-node basis. A reclaimer knows
what zone is required by the allocation request and skips pages from
higher zones. In many cases this will be ok because it's a GFP_HIGHMEM
request of some description. On 64-bit, ZONE_DMA32 requests will cause
some problems but 32-bit devices on 64-bit platforms are increasingly
rare. Historically it would have been a major problem on 32-bit with big
Highmem:Lowmem ratios but such configurations are also now rare and even
where they exist, they are not encouraged. If it really becomes a problem,
it'll manifest as very low reclaim efficiencies.
Signed-off-by: Mel Gorman <[email protected]>
[...]
@@ -2540,14 +2559,14 @@ static inline bool compaction_ready(struct zone *zone,
int order, int classzone_
* If a zone is deemed to be full of pinned pages then just give it a light
* scan then give up on it.
*/
-static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
+static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc,
+ enum zone_type classzone_idx)
{
struct zoneref *z;
struct zone *zone;
unsigned long nr_soft_reclaimed;
unsigned long nr_soft_scanned;
gfp_t orig_mask;
- enum zone_type requested_highidx = gfp_zone(sc->gfp_mask);
/*
* If the number of buffer_heads in the machine exceeds the maximum
@@ -2560,15 +2579,20 @@ static void shrink_zones(struct zonelist *zonelist,
struct scan_control *sc)
for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(sc->gfp_mask), sc->nodemask) {
Using sc->reclaim_idx could be faster/nicer here than gfp_zone()?
Although after "mm, vmscan: Update classzone_idx if buffer_heads_over_limit"
there would need to be a variable for the highmem adjusted value - maybe reuse
"requested_highidx"? Not important though.
- enum zone_type classzone_idx;
-
if (!populated_zone(zone))
continue;
- classzone_idx = requested_highidx;
+ /*
+ * Note that reclaim_idx does not change as it is the highest
+ * zone reclaimed from which for empty zones is a no-op but
+ * classzone_idx is used by shrink_node to test if the slabs
+ * should be shrunk on a given node.
+ */
while (!populated_zone(zone->zone_pgdat->node_zones +
- classzone_idx))
+ classzone_idx)) {
classzone_idx--;
+ continue;
+ }
/*
* Take care memory controller reclaiming has small influence
@@ -2594,8 +2618,8 @@ static void shrink_zones(struct zonelist *zonelist,
struct scan_control *sc)
*/
if (IS_ENABLED(CONFIG_COMPACTION) &&
sc->order > PAGE_ALLOC_COSTLY_ORDER &&
- zonelist_zone_idx(z) <= requested_highidx &&
- compaction_ready(zone, sc->order,
requested_highidx)) {
+ zonelist_zone_idx(z) <= classzone_idx &&
+ compaction_ready(zone, sc->order, classzone_idx)) {
sc->compaction_ready = true;
continue;
}
@@ -2615,7 +2639,7 @@ static void shrink_zones(struct zonelist *zonelist,
struct scan_control *sc)
/* need some check for avoid more shrink_zone() */
}
- shrink_zone(zone, sc, zone_idx(zone) == classzone_idx);
+ shrink_node(zone->zone_pgdat, sc, classzone_idx);
}
/*
@@ -2647,6 +2671,7 @@ static unsigned long do_try_to_free_pages(struct zonelist
*zonelist,
int initial_priority = sc->priority;
unsigned long total_scanned = 0;
unsigned long writeback_threshold;
+ enum zone_type classzone_idx = sc->reclaim_idx;
Hmm, try_to_free_mem_cgroup_pages() seems to call this with sc->reclaim_idx not
explicitly inirialized (e.g. 0). And shrink_all_memory() as well. I probably
didn't check them in v6 and pointed out only try_to_free_pages() (which is now
OK), sorry.
retry:
delayacct_freepages_start();
@@ -2657,7 +2682,7 @@ static unsigned long do_try_to_free_pages(struct zonelist
*zonelist,
vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
sc->priority);
sc->nr_scanned = 0;
- shrink_zones(zonelist, sc);
+ shrink_zones(zonelist, sc, classzone_idx);
Looks like classzone_idx here is only used here to pass to shrink_zones()
unchanged, which means it can just use it directly without a new param?
