Subject: + mm-compaction-do-not-count-migratepages-when-unnecessary.patch added to -mm tree
To: vbabka@xxxxxxx,b.zolnierkie@xxxxxxxxxxx,cl@xxxxxxxxx,iamjoonsoo.kim@xxxxxxx,mgorman@xxxxxxx,mina86@xxxxxxxxxx,minchan@xxxxxxxxxx,n-horiguchi@xxxxxxxxxxxxx,riel@xxxxxxxxxx,rientjes@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 07 May 2014 14:22:41 -0700
The patch titled
Subject: mm/compaction: do not count migratepages when unnecessary
has been added to the -mm tree. Its filename is
mm-compaction-do-not-count-migratepages-when-unnecessary.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-do-not-count-migratepages-when-unnecessary.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-do-not-count-migratepages-when-unnecessary.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm/compaction: do not count migratepages when unnecessary
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@xxxxxxx>
Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/trace/events/compaction.h | 26 +++++++++++++++++++----
mm/compaction.c | 31 ++++++----------------------
2 files changed, 29 insertions(+), 28 deletions(-)
diff -puN include/trace/events/compaction.h~mm-compaction-do-not-count-migratepages-when-unnecessary include/trace/events/compaction.h
--- a/include/trace/events/compaction.h~mm-compaction-do-not-count-migratepages-when-unnecessary
+++ a/include/trace/events/compaction.h
@@ -5,7 +5,9 @@
#define _TRACE_COMPACTION_H
#include <linux/types.h>
+#include <linux/list.h>
#include <linux/tracepoint.h>
+#include <linux/mm_types.h>
#include <trace/events/gfpflags.h>
DECLARE_EVENT_CLASS(mm_compaction_isolate_template,
@@ -47,10 +49,11 @@ DEFINE_EVENT(mm_compaction_isolate_templ
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 +61,22 @@ TRACE_EVENT(mm_compaction_migratepages,
),
TP_fast_assign(
- __entry->nr_migrated = nr_migrated;
+ unsigned long nr_failed = 0;
+ struct page *page;
+
+ /*
+ * 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_entry(page, migratepages, lru)
+ nr_failed++;
+
+ __entry->nr_migrated = nr_all - nr_failed;
__entry->nr_failed = nr_failed;
),
diff -puN mm/compaction.c~mm-compaction-do-not-count-migratepages-when-unnecessary mm/compaction.c
--- a/mm/compaction.c~mm-compaction-do-not-count-migratepages-when-unnecessary
+++ a/mm/compaction.c
@@ -819,22 +819,6 @@ static void compaction_free(struct page
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 */
@@ -1029,7 +1013,6 @@ static int compact_zone(struct zone *zon
migrate_prep_local();
while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
- unsigned long nr_migrate, nr_remaining;
int err;
switch (isolate_migratepages(zone, cc)) {
@@ -1044,20 +1027,20 @@ static int compact_zone(struct zone *zon
;
}
- 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
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
origin.patch
mm-compactionc-isolate_freepages_block-small-tuneup.patch
mm-page_alloc-prevent-migrate_reserve-pages-from-being-misplaced.patch
mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages.patch
mm-page_alloc-debug_vm-checks-for-free_list-placement-of-cma-and-reserve-pages-fix.patch
mm-compaction-clean-up-unused-code-lines.patch
mm-compaction-cleanup-isolate_freepages.patch
mm-compaction-cleanup-isolate_freepages-fix.patch
mm-compaction-cleanup-isolate_freepages-fix-2.patch
mm-migration-add-destination-page-freeing-callback.patch
mm-compaction-return-failed-migration-target-pages-back-to-freelist.patch
mm-compaction-add-per-zone-migration-pfn-cache-for-async-compaction.patch
mm-compaction-embed-migration-mode-in-compact_control.patch
mm-thp-avoid-excessive-compaction-latency-during-fault.patch
mm-compaction-terminate-async-compaction-when-rescheduling.patch
mm-compaction-do-not-count-migratepages-when-unnecessary.patch
mm-compaction-avoid-rescanning-pageblocks-in-isolate_freepages.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
