>From 015fdb03bdf2ad8cc1c0c1b72884d0c635cf6852 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@xxxxxxxxxx>
Date: Sat, 5 May 2012 08:53:50 +0900
Subject: [PATCH 3/3] compaction: introduce new return value of
suitable_migration_target
We call twice suitable_migration_target to confirm it's really
migration target blocks or not. So adding counting scheme in
suitable_migration_target introduces new argument "count_pageblocks".
But at least to me, it hurts code readability.
This patch introduces new return value of suitable_migration_target
so caller can judge when he should count it. IMHO, it helps code readbility
and code size is same due to smart compiler.
barrios@barrios:~/linux-next$ size mm/compaction.o
text data bss dec hex filename
8451 1082 4 9537 2541 mm/compaction.o
barrios@barrios:~/linux-next$ size mm/compaction.o.new
text data bss dec hex filename
8451 1082 4 9537 2541 mm/compaction.o.new
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
mm/compaction.c | 38 ++++++++++++++++++++++++--------------
1 file changed, 24 insertions(+), 14 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 72bd87a..129d9d6 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -397,38 +397,43 @@ static bool rescue_unmovable_pageblock(struct page *page)
return true;
}
+enum result_smt {
+ GOOD_AS_MIGRATION_TARGET,
+ FAIL_UNMOVABLE,
+ FAIL_ETC_REASON,
+};
+
/* Returns true if the page is within a block suitable for migration to */
-static bool suitable_migration_target(struct page *page,
- struct compact_control *cc,
- bool count_pageblocks)
+static enum result_smt suitable_migration_target(struct page *page,
+ struct compact_control *cc)
{
int migratetype = get_pageblock_migratetype(page);
/* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
- return false;
+ return FAIL_ETC_REASON;
/* If the page is a large free page, then allow migration */
if (PageBuddy(page) && page_order(page) >= pageblock_order)
- return true;
+ return GOOD_AS_MIGRATION_TARGET;
/* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
if (cc->mode != COMPACT_ASYNC_UNMOVABLE &&
migrate_async_suitable(migratetype))
- return true;
+ return GOOD_AS_MIGRATION_TARGET;
- if (count_pageblocks && cc->mode == COMPACT_ASYNC_MOVABLE &&
- migratetype == MIGRATE_UNMOVABLE)
- cc->nr_pageblocks_skipped++;
+ if (cc->mode == COMPACT_ASYNC_MOVABLE &&
+ migratetype == MIGRATE_UNMOVABLE)
+ return FAIL_UNMOVABLE;
if (cc->mode != COMPACT_ASYNC_MOVABLE &&
migratetype == MIGRATE_UNMOVABLE &&
rescue_unmovable_pageblock(page))
- return true;
+ return GOOD_AS_MIGRATION_TARGET;
/* Otherwise skip the block */
- return false;
+ return FAIL_ETC_REASON;
}
/*
@@ -471,6 +476,7 @@ static void isolate_freepages(struct zone *zone,
for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
pfn -= pageblock_nr_pages) {
unsigned long isolated;
+ enum result_smt ret;
if (!pfn_valid(pfn))
continue;
@@ -487,9 +493,12 @@ static void isolate_freepages(struct zone *zone,
continue;
/* Check the block is suitable for migration */
- if (!suitable_migration_target(page, cc, true))
+ ret = suitable_migration_target(page, cc);
+ if (ret != GOOD_AS_MIGRATION_TARGET) {
+ if (ret == FAIL_UNMOVABLE)
+ cc->nr_pageblocks_skipped++;
continue;
-
+ }
/*
* Found a block suitable for isolating free pages from. Now
* we disabled interrupts, double check things are ok and
@@ -498,7 +507,8 @@ static void isolate_freepages(struct zone *zone,
*/
isolated = 0;
spin_lock_irqsave(&zone->lock, flags);
- if (suitable_migration_target(page, cc, false)) {
+ ret = suitable_migration_target(page, cc);
+ if (ret == GOOD_AS_MIGRATION_TARGET) {
end_pfn = min(pfn + pageblock_nr_pages, zone_end_pfn);
isolated = isolate_freepages_block(pfn, end_pfn,
freelist, false);
--
1.7.9.5
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>