Subject: + mm-vmscanc-use-div_round_up-for-calculation-of-zones-balance_gap-and-correct-comments.patch added to -mm tree
To: nasa4836@xxxxxxxxx,aquini@xxxxxxxxxx,riel@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 19 May 2014 15:17:04 -0700
The patch titled
Subject: mm/vmscan.c: use DIV_ROUND_UP for calculation of zone's balance_gap and correct comments.
has been added to the -mm tree. Its filename is
mm-vmscanc-use-div_round_up-for-calculation-of-zones-balance_gap-and-correct-comments.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-vmscanc-use-div_round_up-for-calculation-of-zones-balance_gap-and-correct-comments.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-vmscanc-use-div_round_up-for-calculation-of-zones-balance_gap-and-correct-comments.patch
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From: Jianyu Zhan <nasa4836@xxxxxxxxx>
Subject: mm/vmscan.c: use DIV_ROUND_UP for calculation of zone's balance_gap and correct comments.
Currently, we use (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1)
/ KSWAPD_ZONE_BALANCE_GAP_RATIO to avoid a zero gap value. It's better to
use DIV_ROUND_UP macro for neater code and clear meaning.
Besides, the gap value is calculated against the per-zone "managed pages",
not "present pages". This patch also corrects the comment and do some
rephrasing.
Signed-off-by: Jianyu Zhan <nasa4836@xxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Rafael Aquini <aquini@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/swap.h | 8 ++++----
mm/vmscan.c | 10 ++++------
2 files changed, 8 insertions(+), 10 deletions(-)
diff -puN include/linux/swap.h~mm-vmscanc-use-div_round_up-for-calculation-of-zones-balance_gap-and-correct-comments include/linux/swap.h
--- a/include/linux/swap.h~mm-vmscanc-use-div_round_up-for-calculation-of-zones-balance_gap-and-correct-comments
+++ a/include/linux/swap.h
@@ -166,10 +166,10 @@ enum {
#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
/*
- * Ratio between the present memory in the zone and the "gap" that
- * we're allowing kswapd to shrink in addition to the per-zone high
- * wmark, even for zones that already have the high wmark satisfied,
- * in order to provide better per-zone lru behavior. We are ok to
+ * Ratio between zone->managed_pages and the "gap" that above the per-zone
+ * "high_wmark". While balancing nodes, We allow kswapd to shrink zones that
+ * do not meet the (high_wmark + gap) watermark, even which already met the
+ * high_wmark, in order to provide better per-zone lru behavior. We are ok to
* spend not more than 1% of the memory for this zone balancing "gap".
*/
#define KSWAPD_ZONE_BALANCE_GAP_RATIO 100
diff -puN mm/vmscan.c~mm-vmscanc-use-div_round_up-for-calculation-of-zones-balance_gap-and-correct-comments mm/vmscan.c
--- a/mm/vmscan.c~mm-vmscanc-use-div_round_up-for-calculation-of-zones-balance_gap-and-correct-comments
+++ a/mm/vmscan.c
@@ -2298,9 +2298,8 @@ static inline bool compaction_ready(stru
* there is a buffer of free pages available to give compaction
* a reasonable chance of completing and allocating the page
*/
- balance_gap = min(low_wmark_pages(zone),
- (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
- KSWAPD_ZONE_BALANCE_GAP_RATIO);
+ balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
+ zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
watermark = high_wmark_pages(zone) + balance_gap + (2UL << sc->order);
watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0, 0);
@@ -2952,9 +2951,8 @@ static bool kswapd_shrink_zone(struct zo
* high wmark plus a "gap" where the gap is either the low
* watermark or 1% of the zone, whichever is smaller.
*/
- balance_gap = min(low_wmark_pages(zone),
- (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
- KSWAPD_ZONE_BALANCE_GAP_RATIO);
+ balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
+ zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
/*
* If there is no low memory pressure or the zone is balanced then no
_
Patches currently in -mm which might be from nasa4836@xxxxxxxxx are
origin.patch
mm-swapc-clean-up-lru_cache_add-functions.patch
mm-swapc-introduce-put_refcounted_compound_page-helpers-for-spliting-put_compound_page.patch
mm-swapc-split-put_compound_page-function.patch
mm-introdule-compound_head_by_tail.patch
mm-add-comment-for-__mod_zone_page_stat.patch
mm-add-comment-for-__mod_zone_page_stat-checkpatch-fixes.patch
mm-fold-mlocked_vma_newpage-into-its-only-call-site.patch
mm-fold-mlocked_vma_newpage-into-its-only-call-site-checkpatch-fixes.patch
mm-hugetlb-move-the-error-handle-logic-out-of-normal-code-path.patch
mm-vmscanc-use-div_round_up-for-calculation-of-zones-balance_gap-and-correct-comments.patch
linux-next.patch
mm-memcontrol-clean-up-memcg-zoneinfo-lookup.patch
mm-memcontrol-remove-unnecessary-memcg-argument-from-soft-limit-functions.patch
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