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[209.85.220.65]) by mx.google.com with SMTPS id r93sor4290647qkr.27.2018.12.20.11.45.10 for (Google Transport Security); Thu, 20 Dec 2018 11:45:10 -0800 (PST) Received-SPF: pass (google.com: domain of shy828301@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Ljt+A0id; spf=pass (google.com: domain of shy828301@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=shy828301@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HKmYRYZ8i9OtQjopx4/zRiXjDlfBrbzkMJTi5+z4kig=; b=Ljt+A0idXUEnF5LAnsQXnAhP2HjkaChKUTxbo/ITBVf0Jccx9GjxWhOyo3Oax+61Mr gDkiiHqNDoWVakbxfq1VL6G8+xFb/bGUk/5rmfrK8hebHu9k25Sa7BJ4nASHnAnVsGv9 jvIo/5a+WqNhYcdSIozXUg8h3w+Gx4M4iV5tb66MnVNGerWOE63a3NCELEElZqvsJpyz JdjLLiXgjxVsV3r2PwKro5VErhPpvsEZcceRkjH4/JiOrRMK4Yqn3EAl4ZtjAUa1J1Fd 4LMgDchFZrhvWxro7Dx0XWvrrhrOr3u+1pYTIHuELQHdIelUUVD/Zq5exBEN5leeaxFE NFUw== X-Google-Smtp-Source: AFSGD/VBds3C89sGV9++238eDor5qCfEClTVWWva7YtSZqasPDTwvaUnyPK8WL4gMlDVdArK7KM2kSzVi99e2b0vDcU= X-Received: by 2002:a37:97c1:: with SMTP id z184mr25956590qkd.39.1545335109937; Thu, 20 Dec 2018 11:45:09 -0800 (PST) MIME-Version: 1.0 References: <20181214230310.572-1-mgorman@techsingularity.net> <20181214230310.572-7-mgorman@techsingularity.net> In-Reply-To: <20181214230310.572-7-mgorman@techsingularity.net> From: Yang Shi Date: Thu, 20 Dec 2018 11:44:57 -0800 Message-ID: Subject: Re: [PATCH 06/14] mm, migrate: Immediately fail migration of a page with no migration handler To: mgorman@techsingularity.net Cc: Linux MM , David Rientjes , Andrea Arcangeli , torvalds@linux-foundation.org, Michal Hocko , Huang Ying , "Kirill A. Shutemov" , Andrew Morton , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Message-ID: <20181220194457.fGAo2vL272DchFzFxUg00hHnyWshY9vagDxf0MIouFA@z> On Fri, Dec 14, 2018 at 3:03 PM Mel Gorman wrote: > > Pages with no migration handler use a fallback hander which sometimes > works and sometimes persistently fails such as blockdev pages. Migration A minor correction. The above statement sounds not accurate anymore since Jan Kara had patch series (blkdev: avoid migration stalls for blkdev pages) have blockdev use its own migration handler. Thanks, Yang > 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 >