[153/262] mm/page_alloc: remove the throttling logic from the page allocator

Commit Message

Andrew Morton Nov. 5, 2021, 8:42 p.m. UTC

From: Mel Gorman <[e-mail]>
Subject: mm/page_alloc: remove the throttling logic from the page allocator

The page allocator stalls based on the number of pages that are waiting
for writeback to start but this should now be redundant. 
shrink_inactive_list() will wake flusher threads if the LRU tail are
unqueued dirty pages so the flusher should be active.  If it fails to make
progress due to pages under writeback not being completed quickly then it
should stall on VMSCAN_THROTTLE_WRITEBACK.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Mel Gorman <[e-mail]>
Acked-by: Vlastimil Babka <[e-mail]>
Cc: Andreas Dilger <[e-mail]>
Cc: "Darrick J . Wong" <[e-mail]>
Cc: Dave Chinner <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: NeilBrown <[e-mail]>
Cc: Rik van Riel <[e-mail]>
Cc: "Theodore Ts'o" <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/page_alloc.c |   21 +--------------------
 1 file changed, 1 insertion(+), 20 deletions(-)

Patch

--- a/mm/page_alloc.c~mm-page_alloc-remove-the-throttling-logic-from-the-page-allocator
+++ a/mm/page_alloc.c
@@ -4791,30 +4791,11 @@  should_reclaim_retry(gfp_t gfp_mask, uns
 		trace_reclaim_retry_zone(z, order, reclaimable,
 				available, min_wmark, *no_progress_loops, wmark);
 		if (wmark) {
-			/*
-			 * If we didn't make any progress and have a lot of
-			 * dirty + writeback pages then we should wait for
-			 * an IO to complete to slow down the reclaim and
-			 * prevent from pre mature OOM
-			 */
-			if (!did_some_progress) {
-				unsigned long write_pending;
-
-				write_pending = zone_page_state_snapshot(zone,
-							NR_ZONE_WRITE_PENDING);
-
-				if (2 * write_pending > reclaimable) {
-					congestion_wait(BLK_RW_ASYNC, HZ/10);
-					return true;
-				}
-			}
-
 			ret = true;
-			goto out;
+			break;
 		}
 	}
 
-out:
 	/*
 	 * Memory allocation/reclaim might be called from a WQ context and the
 	 * current implementation of the WQ concurrency control doesn't