Re: [PATCH][RFCv2] mm/compaction: reset compaction scanner positions

From: Vlastimil Babka
Date: Fri Mar 20 2015 - 09:49:41 EST

On 03/20/2015 02:00 PM, Gioh Kim wrote:
I'm attaching the patch for discussion.
According to Vlastimil's advice, I move the reseting before compact_zone(),
and write more description.

Vlastimil, can I have your name at Acked-by or Signed-off-by?

Yes. But note below that whitespace seems broken in the patch.

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

Which one do you prefer?

Acked-by, as Signed-off-by is for maintainers who resend the patches towards Linus.

------------------------- 8< ----------------------

From 575983c887e6478ca7cbba49a892dbc4cd69986b Mon Sep 17 00:00:00 2001
From: Gioh Kim <gioh.kim@xxxxxxx>
Date: Fri, 20 Mar 2015 21:09:13 +0900
Subject: [PATCH] [RFCv2] mm/compaction: reset compaction scanner positions

When the compaction is activated via /proc/sys/vm/compact_memory
it would better scan the whole zone.
And some platform, for instance ARM, has the start_pfn of a zone as zero.
Therefore the first try to compaction via /proc doesn't work.
It needs to force to reset compaction scanner position at first.

Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx>
---
mm/compaction.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/mm/compaction.c b/mm/compaction.c
index 8c0d945..ccf48ce 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1587,6 +1587,14 @@ static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
INIT_LIST_HEAD(&cc->freepages);
INIT_LIST_HEAD(&cc->migratepages);

+ /*
+ * When called via /proc/sys/vm/compact_memory
+ * this makes sure we compact the whole zone regardless of
+ * cached scanner positions.
+ */
+ if (cc->order == -1)
+ __reset_isolation_suitable(zone);

Indentation seems off, some tabs vs spaces issue?

+
if (cc->order == -1 || !compaction_deferred(zone, cc->order))
compact_zone(zone, cc);

--
1.7.9.5


--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/