Subject: + mm-vmscanc-avoid-recording-the-original-scan-targets-in-shrink_lruvec.patch added to -mm tree
To: slaoub@xxxxxxxxx,hannes@xxxxxxxxxxx,mgorman@xxxxxxx,mhocko@xxxxxxx,minchan@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 10 Jun 2014 16:33:54 -0700
The patch titled
Subject: mm/vmscan.c: avoid recording the original scan targets in shrink_lruvec()
has been added to the -mm tree. Its filename is
mm-vmscanc-avoid-recording-the-original-scan-targets-in-shrink_lruvec.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-vmscanc-avoid-recording-the-original-scan-targets-in-shrink_lruvec.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-vmscanc-avoid-recording-the-original-scan-targets-in-shrink_lruvec.patch
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From: Chen Yucong <slaoub@xxxxxxxxx>
Subject: mm/vmscan.c: avoid recording the original scan targets in shrink_lruvec()
Via https://lkml.org/lkml/2013/4/10/334, we can find that recording the
original scan targets introduces extra 40 bytes on the stack. This patch
is able to avoid this situation and the call to memcpy(). At the same
time, it does not change the relative design idea.
ratio = original_nr_file / original_nr_anon;
If (nr_file > nr_anon), then ratio = (nr_file - x) / nr_anon.
x = nr_file - ratio * nr_anon;
if (nr_file <= nr_anon), then ratio = nr_file / (nr_anon - x).
x = nr_anon - nr_file / ratio;
Signed-off-by: Chen Yucong <slaoub@xxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 28 +++++++++-------------------
1 file changed, 9 insertions(+), 19 deletions(-)
diff -puN mm/vmscan.c~mm-vmscanc-avoid-recording-the-original-scan-targets-in-shrink_lruvec mm/vmscan.c
--- a/mm/vmscan.c~mm-vmscanc-avoid-recording-the-original-scan-targets-in-shrink_lruvec
+++ a/mm/vmscan.c
@@ -2055,8 +2055,7 @@ out:
static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
{
unsigned long nr[NR_LRU_LISTS];
- unsigned long targets[NR_LRU_LISTS];
- unsigned long nr_to_scan;
+ unsigned long nr_to_scan, ratio;
enum lru_list lru;
unsigned long nr_reclaimed = 0;
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
@@ -2065,8 +2064,8 @@ static void shrink_lruvec(struct lruvec
get_scan_count(lruvec, sc, nr);
- /* Record the original scan target for proportional adjustments later */
- memcpy(targets, nr, sizeof(nr));
+ ratio = (nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE] + 1) /
+ (nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON] + 1);
/*
* Global reclaiming within direct reclaim at DEF_PRIORITY is a normal
@@ -2086,7 +2085,6 @@ static void shrink_lruvec(struct lruvec
while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
nr[LRU_INACTIVE_FILE]) {
unsigned long nr_anon, nr_file, percentage;
- unsigned long nr_scanned;
for_each_evictable_lru(lru) {
if (nr[lru]) {
@@ -2121,15 +2119,13 @@ static void shrink_lruvec(struct lruvec
break;
if (nr_file > nr_anon) {
- unsigned long scan_target = targets[LRU_INACTIVE_ANON] +
- targets[LRU_ACTIVE_ANON] + 1;
+ nr_to_scan = nr_file - ratio * nr_anon;
+ percentage = nr[LRU_FILE] * 100 / nr_file;
lru = LRU_BASE;
- percentage = nr_anon * 100 / scan_target;
} else {
- unsigned long scan_target = targets[LRU_INACTIVE_FILE] +
- targets[LRU_ACTIVE_FILE] + 1;
+ nr_to_scan = nr_anon - nr_file / ratio;
+ percentage = nr[LRU_BASE] * 100 / nr_anon;
lru = LRU_FILE;
- percentage = nr_file * 100 / scan_target;
}
/* Stop scanning the smaller of the LRU */
@@ -2141,14 +2137,8 @@ static void shrink_lruvec(struct lruvec
* scan target and the percentage scanning already complete
*/
lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE;
- nr_scanned = targets[lru] - nr[lru];
- nr[lru] = targets[lru] * (100 - percentage) / 100;
- nr[lru] -= min(nr[lru], nr_scanned);
-
- lru += LRU_ACTIVE;
- nr_scanned = targets[lru] - nr[lru];
- nr[lru] = targets[lru] * (100 - percentage) / 100;
- nr[lru] -= min(nr[lru], nr_scanned);
+ nr[lru] = nr_to_scan * percentage / 100;
+ nr[lru + LRU_ACTIVE] = nr_to_scan - nr[lru];
scan_adjusted = true;
}
_
Patches currently in -mm which might be from slaoub@xxxxxxxxx are
origin.patch
checkpatch-check-git-commit-descriptions.patch
mm-vmscanc-avoid-recording-the-original-scan-targets-in-shrink_lruvec.patch
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