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 0CF008E021C for ; Fri, 14 Dec 2018 18:03:14 -0500 (EST) Received: by mail-ed1-f71.google.com with SMTP id f31so281587edf.17 for ; Fri, 14 Dec 2018 15:03:14 -0800 (PST) Received: from outbound-smtp13.blacknight.com (outbound-smtp13.blacknight.com. [46.22.139.230]) by mx.google.com with ESMTPS id k13si643824edl.377.2018.12.14.15.03.12 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Dec 2018 15:03:12 -0800 (PST) Received: from mail.blacknight.com (unknown [81.17.254.10]) by outbound-smtp13.blacknight.com (Postfix) with ESMTPS id 4AFED1C1D19 for ; Fri, 14 Dec 2018 23:03:12 +0000 (GMT) From: Mel Gorman Subject: [PATCH 06/14] mm, migrate: Immediately fail migration of a page with no migration handler Date: Fri, 14 Dec 2018 23:03:02 +0000 Message-Id: <20181214230310.572-7-mgorman@techsingularity.net> In-Reply-To: <20181214230310.572-1-mgorman@techsingularity.net> References: <20181214230310.572-1-mgorman@techsingularity.net> Sender: owner-linux-mm@kvack.org List-ID: To: Linux-MM Cc: David Rientjes , Andrea Arcangeli , Linus Torvalds , Michal Hocko , ying.huang@intel.com, kirill@shutemov.name, Andrew Morton , Linux List Kernel Mailing , Mel Gorman Pages with no migration handler use a fallback hander which sometimes works and sometimes persistently fails such as blockdev pages. Migration will retry a number of times on these persistent pages which is wasteful during compaction. This patch will fail migration immediately unless the caller is in MIGRATE_SYNC mode which indicates the caller is willing to wait while being persistent. This is not expected to help THP allocation success rates but it does reduce latencies slightly. 1-socket thpfioscale 4.20.0-rc6 4.20.0-rc6 noreserved-v1r4 failfast-v1r4 Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%* Amean fault-both-3 2276.15 ( 0.00%) 3867.54 * -69.92%* Amean fault-both-5 4992.20 ( 0.00%) 5313.20 ( -6.43%) Amean fault-both-7 7373.30 ( 0.00%) 7039.11 ( 4.53%) Amean fault-both-12 11911.52 ( 0.00%) 11328.29 ( 4.90%) Amean fault-both-18 17209.42 ( 0.00%) 16455.34 ( 4.38%) Amean fault-both-24 20943.71 ( 0.00%) 20448.94 ( 2.36%) Amean fault-both-30 22703.00 ( 0.00%) 21655.07 ( 4.62%) Amean fault-both-32 22461.41 ( 0.00%) 21415.35 ( 4.66%) The 2-socket results are not materially different. Scan rates are similar as expected. Signed-off-by: Mel Gorman --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index df17a710e2c7..0e27a10429e2 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -885,7 +885,7 @@ static int fallback_migrate_page(struct address_space *mapping, */ if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) - return -EAGAIN; + return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY; return migrate_page(mapping, newpage, page, mode); } -- 2.16.4