From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by kanga.kvack.org (Postfix) with ESMTP id 7DC468E0002 for ; Fri, 18 Jan 2019 12:53:10 -0500 (EST) Received: by mail-ed1-f69.google.com with SMTP id v4so5124829edm.18 for ; Fri, 18 Jan 2019 09:53:10 -0800 (PST) Received: from outbound-smtp16.blacknight.com (outbound-smtp16.blacknight.com. [46.22.139.233]) by mx.google.com with ESMTPS id b11si2180785edj.393.2019.01.18.09.53.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 18 Jan 2019 09:53:08 -0800 (PST) Received: from mail.blacknight.com (pemlinmail03.blacknight.ie [81.17.254.16]) by outbound-smtp16.blacknight.com (Postfix) with ESMTPS id 803011C35AE for ; Fri, 18 Jan 2019 17:53:08 +0000 (GMT) From: Mel Gorman Subject: [PATCH 08/22] mm, compaction: Ignore the fragmentation avoidance boost for isolation and compaction Date: Fri, 18 Jan 2019 17:51:22 +0000 Message-Id: <20190118175136.31341-9-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 pageblocks get fragmented, watermarks are artifically boosted to reclaim pages to avoid further fragmentation events. However, compaction is often either fragmentation-neutral or moving movable pages away from unmovable/reclaimable pages. As the true watermarks are preserved, allow compaction to ignore the boost factor. The expected impact is very slight as the main benefit is that compaction is slightly more likely to succeed when the system has been fragmented very recently. On both 1-socket and 2-socket machines for THP-intensive allocation during fragmentation the success rate was increased by less than 1% which is marginal. However, detailed tracing indicated that failure of migration due to a premature ENOMEM triggered by watermark checks were eliminated. Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index fc769ff4fb2c..6607cb7131b0 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3071,7 +3071,7 @@ int __isolate_free_page(struct page *page, unsigned int order) * watermark, because we already know our high-order page * exists. */ - watermark = min_wmark_pages(zone) + (1UL << order); + watermark = zone->_watermark[WMARK_MIN] + (1UL << order); if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA)) return 0; -- 2.16.4