The patch titled
Subject: mm: don't wait on congested zones in balance_pgdat()
has been added to the -mm tree. Its filename is
mm-dont-wait-on-congested-zones-in-balance_pgdat.patch
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From: Zlatko Calusic <zlatko.calusic@xxxxxxxx>
Subject: mm: don't wait on congested zones in balance_pgdat()
Commit 92df3a72 (mm: vmscan: throttle reclaim if encountering too many
dirty pages under writeback) introduced waiting on congested zones
based on a sane algorithm in shrink_inactive_list(). What this means
is that there's no more need for throttling and additional heuristics
in balance_pgdat(). So, let's remove it and tidy up the code.
Signed-off-by: Zlatko Calusic <zlatko.calusic@xxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: Johannes Weiner <jweiner@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/vm_event_item.h | 1 -
mm/vmscan.c | 29 +----------------------------
mm/vmstat.c | 1 -
3 files changed, 1 insertion(+), 30 deletions(-)
diff -puN include/linux/vm_event_item.h~mm-dont-wait-on-congested-zones-in-balance_pgdat include/linux/vm_event_item.h
--- a/include/linux/vm_event_item.h~mm-dont-wait-on-congested-zones-in-balance_pgdat
+++ a/include/linux/vm_event_item.h
@@ -36,7 +36,6 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
#endif
PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL,
KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
- KSWAPD_SKIP_CONGESTION_WAIT,
PAGEOUTRUN, ALLOCSTALL, PGROTATED,
#ifdef CONFIG_NUMA_BALANCING
NUMA_PTE_UPDATES,
diff -puN mm/vmscan.c~mm-dont-wait-on-congested-zones-in-balance_pgdat mm/vmscan.c
--- a/mm/vmscan.c~mm-dont-wait-on-congested-zones-in-balance_pgdat
+++ a/mm/vmscan.c
@@ -2617,7 +2617,6 @@ static unsigned long balance_pgdat(pg_da
int *classzone_idx)
{
bool pgdat_is_balanced = false;
- struct zone *unbalanced_zone;
int i;
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
unsigned long total_scanned;
@@ -2648,9 +2647,6 @@ loop_again:
do {
unsigned long lru_pages = 0;
- int has_under_min_watermark_zone = 0;
-
- unbalanced_zone = NULL;
/*
* Scan in the highmem->dma direction for the highest
@@ -2790,17 +2786,7 @@ loop_again:
continue;
}
- if (!zone_balanced(zone, testorder, 0, end_zone)) {
- unbalanced_zone = zone;
- /*
- * We are still under min water mark. This
- * means that we have a GFP_ATOMIC allocation
- * failure risk. Hurry up!
- */
- if (!zone_watermark_ok_safe(zone, order,
- min_wmark_pages(zone), end_zone, 0))
- has_under_min_watermark_zone = 1;
- } else {
+ if (zone_balanced(zone, testorder, 0, end_zone))
/*
* If a zone reaches its high watermark,
* consider it to be no longer congested. It's
@@ -2809,8 +2795,6 @@ loop_again:
* speculatively avoid congestion waits
*/
zone_clear_flag(zone, ZONE_CONGESTED);
- }
-
}
/*
@@ -2828,17 +2812,6 @@ loop_again:
}
/*
- * OK, kswapd is getting into trouble. Take a nap, then take
- * another pass across the zones.
- */
- if (total_scanned && (sc.priority < DEF_PRIORITY - 2)) {
- if (has_under_min_watermark_zone)
- count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT);
- else if (unbalanced_zone)
- wait_iff_congested(unbalanced_zone, BLK_RW_ASYNC, HZ/10);
- }
-
- /*
* We do this so kswapd doesn't build up large priorities for
* example when it is freeing in parallel with allocators. It
* matches the direct reclaim path behaviour in terms of impact
diff -puN mm/vmstat.c~mm-dont-wait-on-congested-zones-in-balance_pgdat mm/vmstat.c
--- a/mm/vmstat.c~mm-dont-wait-on-congested-zones-in-balance_pgdat
+++ a/mm/vmstat.c
@@ -768,7 +768,6 @@ const char * const vmstat_text[] = {
"kswapd_inodesteal",
"kswapd_low_wmark_hit_quickly",
"kswapd_high_wmark_hit_quickly",
- "kswapd_skip_congestion_wait",
"pageoutrun",
"allocstall",
_
Patches currently in -mm which might be from zlatko.calusic@xxxxxxxx are
mm-avoid-calling-pgdat_balanced-needlessly.patch
mm-dont-wait-on-congested-zones-in-balance_pgdat.patch
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