From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AC95DC04AB7 for ; Tue, 14 May 2019 06:20:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 77168208CA for ; Tue, 14 May 2019 06:20:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 77168208CA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 058A86B0007; Tue, 14 May 2019 02:20:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F23986B0008; Tue, 14 May 2019 02:20:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DEB5B6B000A; Tue, 14 May 2019 02:20:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 8D5816B0007 for ; Tue, 14 May 2019 02:20:42 -0400 (EDT) Received: by mail-ed1-f72.google.com with SMTP id l3so7359855edl.10 for ; Mon, 13 May 2019 23:20:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:references:mime-version:content-disposition :in-reply-to:user-agent; bh=/EMQzAezXnn0oYijD9ANQWZeVbNXHm+aZD+2Ibjc4yM=; b=KgoAryjQ1uX97Npp1yoFKxkcEKSscBq8hJDiaiXBhRBHFr4R9D3tw6joLFuZBQwa/X B3zU+UzkkJUi07ifETJswep3xMUbUHOhIOMETsHvTTdbEnsqKS5u9BrvB6qNdzLv2fOf 71fDnLiei2aYNhqmR18KzCdwFUDYg5vnR3RSpKV8eAA2hGcVFGuzAkG7SBC4A3tmYCCC C1BEBEPNjfdhdIyRNdrqsPBud/PBYSD8K9Yfu26GGmuaucnG4/QGVy1B6zqoj/PPkymW uvZPii1soxBS55/7y8xHRMzlBCPX/9gYgBXyPzZJRq2vJnFrcTBEJqfgeZcOzNBPu5S/ 58/Q== X-Original-Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Gm-Message-State: APjAAAVbmkVzxIZ1RvcCXojXvbHhGGrV3pgZx0ak74TAgneX3Hyujyx6 JZWG2kHztnNpCcW6bAbbrDJVD/rsLzKEPiqtPI6FzzyytANCdr0vc/Qk1cPsTFBMbO9f6QphhWp HkUAXIlVQLi221BdMtDkdewPnM9zk1r7x9cytNRAjzwQxPPlieWtLpKXWcOgw8lY= X-Received: by 2002:aa7:db05:: with SMTP id t5mr33091032eds.217.1557814842167; Mon, 13 May 2019 23:20:42 -0700 (PDT) X-Google-Smtp-Source: APXvYqyvAEgaTwClx2T1M6h3xAMKnGcSLsZWlVIwtAjEJ2w/H9i7H1a+bc4S733q5U7TE28musZP X-Received: by 2002:aa7:db05:: with SMTP id t5mr33090969eds.217.1557814841307; Mon, 13 May 2019 23:20:41 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1557814841; cv=none; d=google.com; s=arc-20160816; b=W8K556exMRviFuagvJlpYsUyckXvqDxw+9Yo/XqGS93ndnCuUhF95l+YuXQlyzMjSY SrHUcSMJllQEZxX4zSihB513KQv7Kw04Pd5HJ8T/AzsSG4eQ58mfnVvZhs6SVRkckoGK zYPPChkpZkfTLjoWpJx0seZkfX1D2PfG3rBVML6dfR1LJDYydyCM9y70C0qNZwBoaWmg xKgQquxgx0/BTaUkTWzCKIMB3rloE1reAf9jY1AgAK0mR4LWxg2lYKzruFm7/l59hp2o AMTCzPO+keYbk88A/Uq9CKLqu9bbwWVfzYpCjnCHAueNHHWnkCIp/byy61jJ46rPIWGN 1djQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date; bh=/EMQzAezXnn0oYijD9ANQWZeVbNXHm+aZD+2Ibjc4yM=; b=cu5f4sADFa2T1itMZtzX5tgiih8wA80T6HVdCx4b4TP2HGcNI648RtD9l9QANDugAN Sm/HKrzskjrYzXrbqfZFi6PHwNWRq2ThC5/s7++uoSv2Mn6+L2AxmK9+nW0YjsXOza+h ikTg6qPg+tizgO3UrxH1UzGUc+aNlnbqBrPDwGOZTR8LhZayjn81WHITDCCFzBxGnjMg t9utrpQCrtACDKwctCUJpUfdaT9N2kZugwQ7eel3iAh1QwmPnRKaLJbZy1gSlcKM1Oi5 jLwRWzvUla8X2lcEgWVm1ZXFopC3Egkj0uacySFqd/XBdfZY73gVyjaosTrfdafm2R65 borg== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id f3si2433311edv.9.2019.05.13.23.20.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 13 May 2019 23:20:41 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 8FD3DAD94; Tue, 14 May 2019 06:20:40 +0000 (UTC) Date: Tue, 14 May 2019 08:20:39 +0200 From: Michal Hocko To: Yang Shi Cc: Yang Shi , Huang Ying , Johannes Weiner , Mel Gorman , kirill.shutemov@linux.intel.com, Hugh Dickins , Shakeel Butt , william.kucharski@oracle.com, Andrew Morton , Linux MM , Linux Kernel Mailing List Subject: Re: [v2 PATCH] mm: vmscan: correct nr_reclaimed for THP Message-ID: <20190514062039.GB20868@dhcp22.suse.cz> References: <1557505420-21809-1-git-send-email-yang.shi@linux.alibaba.com> <20190513080929.GC24036@dhcp22.suse.cz> <20190513214503.GB25356@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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: On Mon 13-05-19 21:36:59, Yang Shi wrote: > On Mon, May 13, 2019 at 2:45 PM Michal Hocko wrote: > > > > On Mon 13-05-19 14:09:59, Yang Shi wrote: > > [...] > > > I think we can just account 512 base pages for nr_scanned for > > > isolate_lru_pages() to make the counters sane since PGSCAN_KSWAPD/DIRECT > > > just use it. > > > > > > And, sc->nr_scanned should be accounted as 512 base pages too otherwise we > > > may have nr_scanned < nr_to_reclaim all the time to result in false-negative > > > for priority raise and something else wrong (e.g. wrong vmpressure). > > > > Be careful. nr_scanned is used as a pressure indicator to slab shrinking > > AFAIR. Maybe this is ok but it really begs for much more explaining > > I don't know why my company mailbox didn't receive this email, so I > replied with my personal email. > > It is not used to double slab pressure any more since commit > 9092c71bb724 ("mm: use sc->priority for slab shrink targets"). It uses > sc->priority to determine the pressure for slab shrinking now. > > So, I think we can just remove that "double slab pressure" code. It is > not used actually and looks confusing now. Actually, the "double slab > pressure" does something opposite. The extra inc to sc->nr_scanned > just prevents from raising sc->priority. I have to get in sync with the recent changes. I am aware there were some patches floating around but I didn't get to review them. I was trying to point out that nr_scanned used to have a side effect to be careful about. If it doesn't have anymore then this is getting much more easier of course. Please document everything in the changelog. -- Michal Hocko SUSE Labs