pageblock_pfn_to_page() is used to check there is valid pfn and all pages
in the pageblock is in a single zone. If there is a hole in the pageblock,
passing arbitrary position to pageblock_pfn_to_page() could cause to skip
whole pageblock scanning, instead of just skipping the hole page. For
deterministic behaviour, it's better to always pass pageblock aligned
range to pageblock_pfn_to_page(). It will also help further optimization
on pageblock_pfn_to_page() in the following patch.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
---
mm/compaction.c | 41 ++++++++++++++++++++++++++++++-----------
1 file changed, 30 insertions(+), 11 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 56fa321..8ce36eb 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -555,13 +555,17 @@ unsigned long
isolate_freepages_range(struct compact_control *cc,
unsigned long start_pfn, unsigned long end_pfn)
{
- unsigned long isolated, pfn, block_end_pfn;
+ unsigned long isolated, pfn, block_start_pfn, block_end_pfn;
LIST_HEAD(freelist);
pfn = start_pfn;
+ block_start_pfn = pfn & ~(pageblock_nr_pages - 1);
+ if (block_start_pfn < cc->zone->zone_start_pfn)
+ block_start_pfn = cc->zone->zone_start_pfn;
block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
for (; pfn < end_pfn; pfn += isolated,
+ block_start_pfn = block_end_pfn,
block_end_pfn += pageblock_nr_pages) {
/* Protect pfn from changing by isolate_freepages_block */
unsigned long isolate_start_pfn = pfn;
@@ -574,11 +578,13 @@ isolate_freepages_range(struct compact_control *cc,
* scanning range to right one.
*/
if (pfn >= block_end_pfn) {
+ block_start_pfn = pfn & ~(pageblock_nr_pages - 1);
block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
block_end_pfn = min(block_end_pfn, end_pfn);
}
- if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
+ if (!pageblock_pfn_to_page(block_start_pfn,
+ block_end_pfn, cc->zone))
break;
isolated = isolate_freepages_block(cc, &isolate_start_pfn,
@@ -864,18 +870,23 @@ unsigned long
isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
unsigned long end_pfn)
{
- unsigned long pfn, block_end_pfn;
+ unsigned long pfn, block_start_pfn, block_end_pfn;
/* Scan block by block. First and last block may be incomplete */
pfn = start_pfn;
+ block_start_pfn = pfn & ~(pageblock_nr_pages - 1);
+ if (block_start_pfn < cc->zone->zone_start_pfn)
+ block_start_pfn = cc->zone->zone_start_pfn;
block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
for (; pfn < end_pfn; pfn = block_end_pfn,
+ block_start_pfn = block_end_pfn,
block_end_pfn += pageblock_nr_pages) {
block_end_pfn = min(block_end_pfn, end_pfn);
- if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
+ if (!pageblock_pfn_to_page(block_start_pfn,
+ block_end_pfn, cc->zone))
continue;
pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
@@ -1104,7 +1115,9 @@ int sysctl_compact_unevictable_allowed __read_mostly = 1;
static isolate_migrate_t isolate_migratepages(struct zone *zone,
struct compact_control *cc)
{
- unsigned long low_pfn, end_pfn;
+ unsigned long block_start_pfn;
+ unsigned long block_end_pfn;
+ unsigned long low_pfn;
unsigned long isolate_start_pfn;
struct page *page;
const isolate_mode_t isolate_mode =
@@ -1116,16 +1129,21 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
* initialized by compact_zone()
*/
low_pfn = cc->migrate_pfn;
+ block_start_pfn = cc->migrate_pfn & ~(pageblock_nr_pages - 1);
+ if (block_start_pfn < zone->zone_start_pfn)
+ block_start_pfn = zone->zone_start_pfn;
/* Only scan within a pageblock boundary */
- end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
+ block_end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
/*
* Iterate over whole pageblocks until we find the first suitable.
* Do not cross the free scanner.
*/
- for (; end_pfn <= cc->free_pfn;
- low_pfn = end_pfn, end_pfn += pageblock_nr_pages) {
+ for (; block_end_pfn <= cc->free_pfn;
+ low_pfn = block_end_pfn,
+ block_start_pfn = block_end_pfn,
+ block_end_pfn += pageblock_nr_pages) {
/*
* This can potentially iterate a massively long zone with
@@ -1136,7 +1154,8 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
&& compact_should_abort(cc))
break;
- page = pageblock_pfn_to_page(low_pfn, end_pfn, zone);
+ page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
+ zone);
if (!page)
continue;
@@ -1155,8 +1174,8 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
/* Perform the isolation */
isolate_start_pfn = low_pfn;
- low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn,
- isolate_mode);
+ low_pfn = isolate_migratepages_block(cc, low_pfn,
+ block_end_pfn, isolate_mode);
if (!low_pfn || cc->contended) {
acct_isolated(zone, cc);
--
1.9.1
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