From: Vlastimil Babka <vbabka@suse.cz>
To: linux-mm@kvack.org, Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
David Rientjes <rientjes@google.com>,
Mel Gorman <mgorman@techsingularity.net>,
linux-kernel@vger.kernel.org, kernel-team@fb.com,
Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished()
Date: Fri, 10 Feb 2017 18:23:35 +0100 [thread overview]
Message-ID: <20170210172343.30283-3-vbabka@suse.cz> (raw)
In-Reply-To: <20170210172343.30283-1-vbabka@suse.cz>
When detecting whether compaction has succeeded in forming a high-order page,
__compact_finished() employs a watermark check, followed by an own search for
a suitable page in the freelists. This is not ideal for two reasons:
- The watermark check also searches high-order freelists, but has a less strict
criteria wrt fallback. It's therefore redundant and waste of cycles. This was
different in the past when high-order watermark check attempted to apply
reserves to high-order pages.
- The watermark check might actually fail due to lack of order-0 pages.
Compaction can't help with that, so there's no point in continuing because of
that. It's possible that high-order page still exists and it terminates.
This patch therefore removes the watermark check. This should save some cycles
and terminate compaction sooner in some cases.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/compaction.c | 8 --------
1 file changed, 8 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 0409a4ad6ea1..fc88e7b6fe37 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1291,7 +1291,6 @@ static enum compact_result __compact_finished(struct zone *zone, struct compact_
const int migratetype)
{
unsigned int order;
- unsigned long watermark;
if (cc->contended || fatal_signal_pending(current))
return COMPACT_CONTENDED;
@@ -1319,13 +1318,6 @@ static enum compact_result __compact_finished(struct zone *zone, struct compact_
if (is_via_compact_memory(cc->order))
return COMPACT_CONTINUE;
- /* Compaction run is not finished if the watermark is not met */
- watermark = zone->watermark[cc->alloc_flags & ALLOC_WMARK_MASK];
-
- if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx,
- cc->alloc_flags))
- return COMPACT_CONTINUE;
-
/* Direct compactor: Is a suitable page free? */
for (order = cc->order; order < MAX_ORDER; order++) {
struct free_area *area = &zone->free_area[order];
--
2.11.0
next prev parent reply other threads:[~2017-02-10 19:13 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-10 17:23 [PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka
2017-02-10 17:23 ` [PATCH v2 01/10] mm, compaction: reorder fields in struct compact_control Vlastimil Babka
2017-02-13 10:49 ` Mel Gorman
2017-02-14 16:33 ` Johannes Weiner
2017-02-10 17:23 ` Vlastimil Babka [this message]
2017-02-13 10:49 ` [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished() Mel Gorman
2017-02-14 16:34 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 03/10] mm, page_alloc: split smallest stolen page in fallback Vlastimil Babka
2017-02-13 10:51 ` Mel Gorman
2017-02-13 10:54 ` Vlastimil Babka
2017-02-14 16:59 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 04/10] mm, page_alloc: count movable pages when stealing from pageblock Vlastimil Babka
2017-02-13 10:53 ` Mel Gorman
2017-02-14 10:07 ` Xishi Qiu
2017-02-15 10:47 ` Vlastimil Babka
2017-02-15 11:56 ` Xishi Qiu
2017-02-17 16:21 ` Vlastimil Babka
2017-02-14 18:10 ` Johannes Weiner
2017-02-17 16:09 ` Vlastimil Babka
2017-02-10 17:23 ` [PATCH v2 05/10] mm, compaction: change migrate_async_suitable() to suitable_migration_source() Vlastimil Babka
2017-02-13 10:53 ` Mel Gorman
2017-02-14 18:12 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 06/10] mm, compaction: add migratetype to compact_control Vlastimil Babka
2017-02-13 10:53 ` Mel Gorman
2017-02-14 18:15 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 07/10] mm, compaction: restrict async compaction to pageblocks of same migratetype Vlastimil Babka
2017-02-13 10:56 ` Mel Gorman
2017-02-14 20:10 ` Johannes Weiner
2017-02-17 16:32 ` Vlastimil Babka
2017-02-17 17:39 ` Johannes Weiner
2017-02-10 17:23 ` [PATCH v2 08/10] mm, compaction: finish whole pageblock to reduce fragmentation Vlastimil Babka
2017-02-13 10:57 ` Mel Gorman
2017-02-16 11:44 ` Johannes Weiner
2017-02-10 17:23 ` [RFC v2 09/10] mm, page_alloc: disallow migratetype fallback in fastpath Vlastimil Babka
2017-02-10 17:23 ` [RFC v2 10/10] mm, page_alloc: introduce MIGRATE_MIXED migratetype Vlastimil Babka
2017-03-08 2:16 ` Yisheng Xie
2017-03-08 7:07 ` Vlastimil Babka
2017-03-13 2:16 ` Yisheng Xie
2017-02-13 11:07 ` [PATCH v2 00/10] try to reduce fragmenting fallbacks Mel Gorman
2017-02-15 14:29 ` Vlastimil Babka
2017-02-15 16:11 ` Vlastimil Babka
2017-02-15 20:11 ` Vlastimil Babka
2017-02-16 15:12 ` Vlastimil Babka
2017-02-17 15:24 ` Vlastimil Babka
2017-02-20 12:30 ` Vlastimil Babka
2017-02-23 16:01 ` Mel Gorman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170210172343.30283-3-vbabka@suse.cz \
--to=vbabka@suse.cz \
--cc=hannes@cmpxchg.org \
--cc=iamjoonsoo.kim@lge.com \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=rientjes@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).