From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by kanga.kvack.org (Postfix) with ESMTP id 6AFBC8E0002 for ; Fri, 18 Jan 2019 12:53:00 -0500 (EST) Received: by mail-ed1-f71.google.com with SMTP id d41so5132626eda.12 for ; Fri, 18 Jan 2019 09:53:00 -0800 (PST) Received: from outbound-smtp08.blacknight.com (outbound-smtp08.blacknight.com. [46.22.139.13]) by mx.google.com with ESMTPS id h13si7559633edf.24.2019.01.18.09.52.58 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 18 Jan 2019 09:52:58 -0800 (PST) Received: from mail.blacknight.com (pemlinmail03.blacknight.ie [81.17.254.16]) by outbound-smtp08.blacknight.com (Postfix) with ESMTPS id 579DF1C35A9 for ; Fri, 18 Jan 2019 17:52:58 +0000 (GMT) From: Mel Gorman Subject: [PATCH 07/22] mm, compaction: Always finish scanning of a full pageblock Date: Fri, 18 Jan 2019 17:51:21 +0000 Message-Id: <20190118175136.31341-8-mgorman@techsingularity.net> In-Reply-To: <20190118175136.31341-1-mgorman@techsingularity.net> References: <20190118175136.31341-1-mgorman@techsingularity.net> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: David Rientjes , Andrea Arcangeli , Vlastimil Babka , Linux List Kernel Mailing , Linux-MM , Mel Gorman When compaction is finishing, it uses a flag to ensure the pageblock is complete but it makes sense to always complete migration of a pageblock. Minimally, skip information is based on a pageblock and partially scanned pageblocks may incur more scanning in the future. The pageblock skip handling also becomes more strict later in the series and the hint is more useful if a complete pageblock was always scanned. The potentially impacts latency as more scanning is done but it's not a consistent win or loss as the scanning is not always a high percentage of the pageblock and sometimes it is offset by future reductions in scanning. Hence, the results are not presented this time due to a misleading mix of gains/losses without any clear pattern. However, full scanning of the pageblock is important for later patches. Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka --- mm/compaction.c | 19 ++++++++----------- mm/internal.h | 1 - 2 files changed, 8 insertions(+), 12 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 32a88b49f973..3d11c209614a 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1331,16 +1331,14 @@ static enum compact_result __compact_finished(struct compact_control *cc) if (is_via_compact_memory(cc->order)) return COMPACT_CONTINUE; - if (cc->finishing_block) { - /* - * We have finished the pageblock, but better check again that - * we really succeeded. - */ - if (IS_ALIGNED(cc->migrate_pfn, pageblock_nr_pages)) - cc->finishing_block = false; - else - return COMPACT_CONTINUE; - } + /* + * Always finish scanning a pageblock to reduce the possibility of + * fallbacks in the future. This is particularly important when + * migration source is unmovable/reclaimable but it's not worth + * special casing. + */ + if (!IS_ALIGNED(cc->migrate_pfn, pageblock_nr_pages)) + return COMPACT_CONTINUE; /* Direct compactor: Is a suitable page free? */ for (order = cc->order; order < MAX_ORDER; order++) { @@ -1382,7 +1380,6 @@ static enum compact_result __compact_finished(struct compact_control *cc) return COMPACT_SUCCESS; } - cc->finishing_block = true; return COMPACT_CONTINUE; } } diff --git a/mm/internal.h b/mm/internal.h index f40d06d70683..9b32f4cab0ae 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -203,7 +203,6 @@ struct compact_control { bool direct_compaction; /* False from kcompactd or /proc/... */ bool whole_zone; /* Whole zone should/has been scanned */ bool contended; /* Signal lock or sched contention */ - bool finishing_block; /* Finishing current pageblock */ }; unsigned long -- 2.16.4