Re: [PATCH 2/2] mm/compaction: fix to initialize free scanner properly
On 04/03/2014 10:57 AM, Heesub Shin wrote: Free scanner does not works well on systems having zones which do not span to pageblock-aligned boundary. zone->compact_cached_free_pfn is reset when the migration and free scanner across or compaction restarts. After the reset, if end_pfn of the zone was not aligned to pageblock_nr_pages, free scanner tries to isolate free pages from the middle of pageblock to the end, which can be very small range. Hm good catch. I think that the same problem can happen (at least theoretically) through zone->compact_cached_free_pfn with CONFIG_HOLES_IN_ZONE enabled. Then compact_cached_free_pfn could be set to a non-aligned-to-pageblock pfn and spoil scans. I'll send a patch that solves it on isolate_freepages() level, which allows further simplification of the function. Vlastimil Signed-off-by: Heesub Shin Cc: Dongjun Shin Cc: Sunghwan Yun --- mm/compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index 1ef9144..fefe1da 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -983,7 +983,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc) */ cc->migrate_pfn = zone->compact_cached_migrate_pfn; cc->free_pfn = zone->compact_cached_free_pfn; - if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) { + if (cc->free_pfn < start_pfn || cc->free_pfn >= end_pfn) { cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1); zone->compact_cached_free_pfn = cc->free_pfn; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/2] mm/compaction: fix to initialize free scanner properly
On 04/03/2014 10:57 AM, Heesub Shin wrote: Free scanner does not works well on systems having zones which do not span to pageblock-aligned boundary. zone-compact_cached_free_pfn is reset when the migration and free scanner across or compaction restarts. After the reset, if end_pfn of the zone was not aligned to pageblock_nr_pages, free scanner tries to isolate free pages from the middle of pageblock to the end, which can be very small range. Hm good catch. I think that the same problem can happen (at least theoretically) through zone-compact_cached_free_pfn with CONFIG_HOLES_IN_ZONE enabled. Then compact_cached_free_pfn could be set to a non-aligned-to-pageblock pfn and spoil scans. I'll send a patch that solves it on isolate_freepages() level, which allows further simplification of the function. Vlastimil Signed-off-by: Heesub Shin heesub.s...@samsung.com Cc: Dongjun Shin d.j.s...@samsung.com Cc: Sunghwan Yun sunghwan@samsung.com --- mm/compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index 1ef9144..fefe1da 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -983,7 +983,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc) */ cc-migrate_pfn = zone-compact_cached_migrate_pfn; cc-free_pfn = zone-compact_cached_free_pfn; - if (cc-free_pfn start_pfn || cc-free_pfn end_pfn) { + if (cc-free_pfn start_pfn || cc-free_pfn = end_pfn) { cc-free_pfn = end_pfn ~(pageblock_nr_pages-1); zone-compact_cached_free_pfn = cc-free_pfn; } -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 2/2] mm/compaction: fix to initialize free scanner properly
Free scanner does not works well on systems having zones which do not span to pageblock-aligned boundary. zone->compact_cached_free_pfn is reset when the migration and free scanner across or compaction restarts. After the reset, if end_pfn of the zone was not aligned to pageblock_nr_pages, free scanner tries to isolate free pages from the middle of pageblock to the end, which can be very small range. Signed-off-by: Heesub Shin Cc: Dongjun Shin Cc: Sunghwan Yun --- mm/compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index 1ef9144..fefe1da 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -983,7 +983,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc) */ cc->migrate_pfn = zone->compact_cached_migrate_pfn; cc->free_pfn = zone->compact_cached_free_pfn; - if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) { + if (cc->free_pfn < start_pfn || cc->free_pfn >= end_pfn) { cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1); zone->compact_cached_free_pfn = cc->free_pfn; } -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 2/2] mm/compaction: fix to initialize free scanner properly
Free scanner does not works well on systems having zones which do not span to pageblock-aligned boundary. zone-compact_cached_free_pfn is reset when the migration and free scanner across or compaction restarts. After the reset, if end_pfn of the zone was not aligned to pageblock_nr_pages, free scanner tries to isolate free pages from the middle of pageblock to the end, which can be very small range. Signed-off-by: Heesub Shin heesub.s...@samsung.com Cc: Dongjun Shin d.j.s...@samsung.com Cc: Sunghwan Yun sunghwan@samsung.com --- mm/compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index 1ef9144..fefe1da 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -983,7 +983,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc) */ cc-migrate_pfn = zone-compact_cached_migrate_pfn; cc-free_pfn = zone-compact_cached_free_pfn; - if (cc-free_pfn start_pfn || cc-free_pfn end_pfn) { + if (cc-free_pfn start_pfn || cc-free_pfn = end_pfn) { cc-free_pfn = end_pfn ~(pageblock_nr_pages-1); zone-compact_cached_free_pfn = cc-free_pfn; } -- 1.8.3.2 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/