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Diffstat (limited to 'mm')
-rw-r--r--mm/vmscan.c42
1 files changed, 39 insertions, 3 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 15e3a29fdb23..7b0573f33a27 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -751,7 +751,9 @@ static noinline_for_stack void free_page_list(struct list_head *free_pages)
static unsigned long shrink_page_list(struct list_head *page_list,
struct zone *zone,
struct scan_control *sc,
- int priority)
+ int priority,
+ unsigned long *ret_nr_dirty,
+ unsigned long *ret_nr_writeback)
{
LIST_HEAD(ret_pages);
LIST_HEAD(free_pages);
@@ -759,6 +761,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
unsigned long nr_dirty = 0;
unsigned long nr_congested = 0;
unsigned long nr_reclaimed = 0;
+ unsigned long nr_writeback = 0;
cond_resched();
@@ -795,6 +798,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
(PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
if (PageWriteback(page)) {
+ nr_writeback++;
/*
* Synchronous reclaim cannot queue pages for
* writeback due to the possibility of stack overflow
@@ -1000,6 +1004,8 @@ keep_lumpy:
list_splice(&ret_pages, page_list);
count_vm_events(PGACTIVATE, pgactivate);
+ *ret_nr_dirty += nr_dirty;
+ *ret_nr_writeback += nr_writeback;
return nr_reclaimed;
}
@@ -1460,6 +1466,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
unsigned long nr_taken;
unsigned long nr_anon;
unsigned long nr_file;
+ unsigned long nr_dirty = 0;
+ unsigned long nr_writeback = 0;
isolate_mode_t reclaim_mode = ISOLATE_INACTIVE;
while (unlikely(too_many_isolated(zone, file, sc))) {
@@ -1512,12 +1520,14 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
spin_unlock_irq(&zone->lru_lock);
- nr_reclaimed = shrink_page_list(&page_list, zone, sc, priority);
+ nr_reclaimed = shrink_page_list(&page_list, zone, sc, priority,
+ &nr_dirty, &nr_writeback);
/* Check if we should syncronously wait for writeback */
if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
set_reclaim_mode(priority, sc, true);
- nr_reclaimed += shrink_page_list(&page_list, zone, sc, priority);
+ nr_reclaimed += shrink_page_list(&page_list, zone, sc,
+ priority, &nr_dirty, &nr_writeback);
}
local_irq_disable();
@@ -1527,6 +1537,32 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list);
+ /*
+ * If reclaim is isolating dirty pages under writeback, it implies
+ * that the long-lived page allocation rate is exceeding the page
+ * laundering rate. Either the global limits are not being effective
+ * at throttling processes due to the page distribution throughout
+ * zones or there is heavy usage of a slow backing device. The
+ * only option is to throttle from reclaim context which is not ideal
+ * as there is no guarantee the dirtying process is throttled in the
+ * same way balance_dirty_pages() manages.
+ *
+ * This scales the number of dirty pages that must be under writeback
+ * before throttling depending on priority. It is a simple backoff
+ * function that has the most effect in the range DEF_PRIORITY to
+ * DEF_PRIORITY-2 which is the priority reclaim is considered to be
+ * in trouble and reclaim is considered to be in trouble.
+ *
+ * DEF_PRIORITY 100% isolated pages must be PageWriteback to throttle
+ * DEF_PRIORITY-1 50% must be PageWriteback
+ * DEF_PRIORITY-2 25% must be PageWriteback, kswapd in trouble
+ * ...
+ * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any
+ * isolated page is PageWriteback
+ */
+ if (nr_writeback && nr_writeback >= (nr_taken >> (DEF_PRIORITY-priority)))
+ wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
+
trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
zone_idx(zone),
nr_scanned, nr_reclaimed,