[PATCH 26/34] mm, vmscan: avoid passing in remaining unnecessarily to prepare_kswapd_sleep

From	Mel Gorman <mgorman@techsingularity.net>
Newsgroups	linux.kernel
Subject	[PATCH 26/34] mm, vmscan: avoid passing in remaining unnecessarily to prepare_kswapd_sleep
Date	2016-07-08 11:50 +0200
Message-ID	<rSAA2-2Xn-33@gated-at.bofh.it> (permalink)
References	<rSAqm-2Tv-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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As pointed out by Minchan Kim, the first call to prepare_kswapd_sleep
always passes in 0 for remaining and the second call can trivially
check the parameter in advance.

Suggested-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/vmscan.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6d5c78e2312b..8a67aa53aa7b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3020,15 +3020,10 @@ static bool zone_balanced(struct zone *zone, int order, int classzone_idx)
  *
  * Returns true if kswapd is ready to sleep
  */
-static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
-					int classzone_idx)
+static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx)
 {
 	int i;
 
-	/* If a direct reclaimer woke kswapd within HZ/10, it's premature */
-	if (remaining)
-		return false;
-
 	/*
 	 * The throttled processes are normally woken up in balance_pgdat() as
 	 * soon as pfmemalloc_watermark_ok() is true. But there is a potential
@@ -3243,7 +3238,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_o
 	prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
 
 	/* Try to sleep for a short interval */
-	if (prepare_kswapd_sleep(pgdat, reclaim_order, remaining, classzone_idx)) {
+	if (prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) {
 		/*
 		 * Compaction records what page blocks it recently failed to
 		 * isolate pages from and skips them in the future scanning.
@@ -3278,7 +3273,8 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_o
 	 * After a short sleep, check if it was a premature sleep. If not, then
 	 * go fully to sleep until explicitly woken up.
 	 */
-	if (prepare_kswapd_sleep(pgdat, reclaim_order, remaining, classzone_idx)) {
+	if (!remaining &&
+	    prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) {
 		trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
 
 		/*
-- 
2.6.4

Thread

[PATCH 00/34] Move LRU page reclaim from zones to nodes v9 Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 09/34] mm, vmscan: simplify the logic deciding whether kswapd sleeps Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 01/34] mm, vmstat: add infrastructure for per-node vmstats Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 13/34] mm, vmscan: make shrink_node decisions more node-centric Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 16/34] mm, page_alloc: consider dirtyable memory in terms of nodes Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 20/34] mm: move vmscan writes and file write accounting to the node Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 12/34] mm: vmscan: do not reclaim from kswapd if there is any eligible zone Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 24/34] mm, vmscan: avoid passing in classzone_idx unnecessarily to shrink_node Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 14/34] mm, memcg: move memcg limit enforcement from zones to nodes Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 04/34] mm, mmzone: clarify the usage of zone padding Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 02/34] mm, vmscan: move lru_lock to the node Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 15/34] mm, workingset: make working set detection node-aware Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 23/34] mm: convert zone_reclaim to node_reclaim Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:40 +0200
  [PATCH 07/34] mm, vmscan: make kswapd reclaim in terms of nodes Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 30/34] mm: page_alloc: cache the last node whose dirty limit is reached Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 31/34] mm: vmstat: replace __count_zone_vm_events with a zone id equivalent Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 34/34] mm, vmstat: remove zone and node double accounting by approximating retries Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 10/34] mm, vmscan: by default have direct reclaim only shrink once per node Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 32/34] mm: vmstat: account per-zone stalls and pages skipped during reclaim Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 25/34] mm, vmscan: avoid passing in classzone_idx unnecessarily to compaction_ready Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 28/34] mm, vmscan: add classzone information to tracepoints Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 27/34] mm, vmscan: Have kswapd reclaim from all zones if reclaiming and buffer_heads_over_limit Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 26/34] mm, vmscan: avoid passing in remaining unnecessarily to prepare_kswapd_sleep Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 29/34] mm, page_alloc: remove fair zone allocation policy Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 22/34] mm, page_alloc: wake kswapd based on the highest eligible zone Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 33/34] mm, vmstat: print node-based stats in zoneinfo file Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200
  [PATCH 19/34] mm: move most file-based accounting to the node Mel Gorman <mgorman@techsingularity.net> - 2016-07-08 11:50 +0200

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