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authorVlastimil Babka <vbabka@suse.cz>2014-06-04 16:08:32 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-21 09:23:07 -0800
commit41c9323cf11df2465a3064591b669d90111b6f9e (patch)
tree285e7f3f632298a99a6159eb7f05c3f331fddd23
parent1c99371f2bd5a31e66b8199c3e66629043d98a6c (diff)
mm/compaction: do not count migratepages when unnecessary
commit f8c9301fa5a2a8b873c67f2a3d8230d5c13f61b7 upstream. During compaction, update_nr_listpages() has been used to count remaining non-migrated and free pages after a call to migrage_pages(). The freepages counting has become unneccessary, and it turns out that migratepages counting is also unnecessary in most cases. The only situation when it's needed to count cc->migratepages is when migrate_pages() returns with a negative error code. Otherwise, the non-negative return value is the number of pages that were not migrated, which is exactly the count of remaining pages in the cc->migratepages list. Furthermore, any non-zero count is only interesting for the tracepoint of mm_compaction_migratepages events, because after that all remaining unmigrated pages are put back and their count is set to 0. This patch therefore removes update_nr_listpages() completely, and changes the tracepoint definition so that the manual counting is done only when the tracepoint is enabled, and only when migrate_pages() returns a negative error code. Furthermore, migrate_pages() and the tracepoints won't be called when there's nothing to migrate. This potentially avoids some wasted cycles and reduces the volume of uninteresting mm_compaction_migratepages events where "nr_migrated=0 nr_failed=0". In the stress-highalloc mmtest, this was about 75% of the events. The mm_compaction_isolate_migratepages event is better for determining that nothing was isolated for migration, and this one was just duplicating the info. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Cc: Christoph Lameter <cl@linux.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/trace/events/compaction.h25
-rw-r--r--mm/compaction.c31
2 files changed, 28 insertions, 28 deletions
diff --git a/include/trace/events/compaction.h b/include/trace/events/compaction.h
index 06f544ef2f6f..c6814b917bdf 100644
--- a/include/trace/events/compaction.h
+++ b/include/trace/events/compaction.h
@@ -5,6 +5,7 @@
#define _TRACE_COMPACTION_H
#include <linux/types.h>
+#include <linux/list.h>
#include <linux/tracepoint.h>
#include <trace/events/gfpflags.h>
@@ -47,10 +48,11 @@ DEFINE_EVENT(mm_compaction_isolate_template, mm_compaction_isolate_freepages,
TRACE_EVENT(mm_compaction_migratepages,
- TP_PROTO(unsigned long nr_migrated,
- unsigned long nr_failed),
+ TP_PROTO(unsigned long nr_all,
+ int migrate_rc,
+ struct list_head *migratepages),
- TP_ARGS(nr_migrated, nr_failed),
+ TP_ARGS(nr_all, migrate_rc, migratepages),
TP_STRUCT__entry(
__field(unsigned long, nr_migrated)
@@ -58,7 +60,22 @@ TRACE_EVENT(mm_compaction_migratepages,
),
TP_fast_assign(
- __entry->nr_migrated = nr_migrated;
+ unsigned long nr_failed = 0;
+ struct list_head *page_lru;
+
+ /*
+ * migrate_pages() returns either a non-negative number
+ * with the number of pages that failed migration, or an
+ * error code, in which case we need to count the remaining
+ * pages manually
+ */
+ if (migrate_rc >= 0)
+ nr_failed = migrate_rc;
+ else
+ list_for_each(page_lru, migratepages)
+ nr_failed++;
+
+ __entry->nr_migrated = nr_all - nr_failed;
__entry->nr_failed = nr_failed;
),
diff --git a/mm/compaction.c b/mm/compaction.c
index 4d38c85265f5..d85ca947cd74 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -822,22 +822,6 @@ static void compaction_free(struct page *page, unsigned long data)
cc->nr_freepages++;
}
-/*
- * We cannot control nr_migratepages fully when migration is running as
- * migrate_pages() has no knowledge of of compact_control. When migration is
- * complete, we count the number of pages on the list by hand.
- */
-static void update_nr_listpages(struct compact_control *cc)
-{
- int nr_migratepages = 0;
- struct page *page;
-
- list_for_each_entry(page, &cc->migratepages, lru)
- nr_migratepages++;
-
- cc->nr_migratepages = nr_migratepages;
-}
-
/* possible outcome of isolate_migratepages */
typedef enum {
ISOLATE_ABORT, /* Abort compaction now */
@@ -1032,7 +1016,6 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
migrate_prep_local();
while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
- unsigned long nr_migrate, nr_remaining;
int err;
switch (isolate_migratepages(zone, cc)) {
@@ -1047,20 +1030,20 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
;
}
- nr_migrate = cc->nr_migratepages;
+ if (!cc->nr_migratepages)
+ continue;
+
err = migrate_pages(&cc->migratepages, compaction_alloc,
compaction_free, (unsigned long)cc, cc->mode,
MR_COMPACTION);
- update_nr_listpages(cc);
- nr_remaining = cc->nr_migratepages;
- trace_mm_compaction_migratepages(nr_migrate - nr_remaining,
- nr_remaining);
+ trace_mm_compaction_migratepages(cc->nr_migratepages, err,
+ &cc->migratepages);
- /* Release isolated pages not migrated */
+ /* All pages were either migrated or will be released */
+ cc->nr_migratepages = 0;
if (err) {
putback_movable_pages(&cc->migratepages);
- cc->nr_migratepages = 0;
/*
* migrate_pages() may return -ENOMEM when scanners meet
* and we want compact_finished() to detect it