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[141.146.126.78]) by mx.google.com with ESMTPS id q68si2074204qkb.286.2019.07.31.14.11.11 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 31 Jul 2019 14:11:11 -0700 (PDT) Received-SPF: pass (google.com: domain of mike.kravetz@oracle.com designates 141.146.126.78 as permitted sender) client-ip=141.146.126.78; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b="iuT/ehJL"; spf=pass (google.com: domain of mike.kravetz@oracle.com designates 141.146.126.78 as permitted sender) smtp.mailfrom=mike.kravetz@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x6VL8vL4165405; Wed, 31 Jul 2019 21:11:07 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=rGOpE1K1seHogZ0v0vORCXGLdurKCucP7xDezduMaQg=; b=iuT/ehJLyJhBOy1y/iDHREcUYlOM80E8e3wO2yHP2CAjoqR8TuG0bym9TdariihNbvCX GTbIRNMRNzd/EEDQoKkYjz2ot09j3WUc+hmC+3VRvfzR44MuuBPxczIeLMYSpS423JKy mOMy7rt2OB4wZ++gyjtQ+tEIi9tMHNTtrYdnxjfweFoI6iAqfkV6DS5vQ3BlWmgDoFqf SbK4cJrdDRv267vO2WzikXriwA7oTdMxvjbkko4f9Aaw401TQL5wYydvSak9fGo1hMz/ unC3SW8WkJFW1d8YxafNQsWmLNPWUJ+4cxeUUf9gq3EYtIbJvMMAi/4Fqa7ZCzt9909S ww== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2120.oracle.com with ESMTP id 2u0ejpqrpd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 31 Jul 2019 21:11:07 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x6VL7nx2168911; Wed, 31 Jul 2019 21:11:07 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3020.oracle.com with ESMTP id 2u2jp5gn3d-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 31 Jul 2019 21:11:07 +0000 Received: from abhmp0013.oracle.com (abhmp0013.oracle.com [141.146.116.19]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x6VLB2BH024191; Wed, 31 Jul 2019 21:11:02 GMT Received: from [192.168.1.222] (/71.63.128.209) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 31 Jul 2019 14:11:02 -0700 Subject: Re: [RFC PATCH 1/3] mm, reclaim: make should_continue_reclaim perform dryrun detection To: Vlastimil Babka , Hillf Danton , Mel Gorman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko , Johannes Weiner , Andrew Morton References: <20190724175014.9935-1-mike.kravetz@oracle.com> <20190724175014.9935-2-mike.kravetz@oracle.com> <20190725080551.GB2708@suse.de> <295a37b1-8257-9b4a-b586-9a4990cc9d35@suse.cz> From: Mike Kravetz Message-ID: Date: Wed, 31 Jul 2019 14:11:00 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <295a37b1-8257-9b4a-b586-9a4990cc9d35@suse.cz> Content-Type: text/plain; charset=iso-8859-15 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9335 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1907310212 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9335 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1907310212 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 7/31/19 4:08 AM, Vlastimil Babka wrote: > > I agree this is an improvement overall, but perhaps the patch does too > many things at once. The reshuffle is one thing and makes sense. The > change of the last return condition could perhaps be separate. Also > AFAICS the ultimate result is that when nr_reclaimed == 0, the function > will now always return false. Which makes the initial test for > __GFP_RETRY_MAYFAIL and the comments there misleading. There will no > longer be a full LRU scan guaranteed - as long as the scanned LRU chunk > yields no reclaimed page, we abort. Can someone help me understand why nr_scanned == 0 guarantees a full LRU scan? FWICS, nr_scanned used in this context is only incremented in shrink_page_list and potentially shrink_zones. In the stall case I am looking at, there are MANY cases in which nr_scanned is only a few pages and none of those are reclaimed. Can we not get nr_scanned == 0 on an arbitrary chunk of the LRU? I must be missing something, because I do not see how nr_scanned == 0 guarantees a full scan. -- Mike Kravetz 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=-2.2 required=3.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 54274C433FF for ; Thu, 1 Aug 2019 04:22:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EF170206B8 for ; Thu, 1 Aug 2019 04:22:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EF170206B8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sina.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8705C8E0005; Thu, 1 Aug 2019 00:22:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 821D28E0001; Thu, 1 Aug 2019 00:22:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6E9978E0005; Thu, 1 Aug 2019 00:22:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-pf1-f198.google.com (mail-pf1-f198.google.com [209.85.210.198]) by kanga.kvack.org (Postfix) with ESMTP id 38E278E0001 for ; Thu, 1 Aug 2019 00:22:54 -0400 (EDT) Received: by mail-pf1-f198.google.com with SMTP id e20so44833659pfd.3 for ; Wed, 31 Jul 2019 21:22:54 -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:from:to:cc :subject:date:message-id:in-reply-to:references:user-agent :mime-version:content-language:precedence:list-id:archived-at :list-archive:list-post:content-transfer-encoding; bh=YWQfKGIde2FQKMsI9cImY1CNyF8U748+3m93N97mArI=; b=orottsoukbnNw17hBZACpI0ikWu9vUVztRxLcRA1+DriSdemRZWH+g8y41k4G4Fnk0 Xk4bHKcfEvvYYgw179fsVIYMa83BAy6L0LGs3s2emmql/vRPK/83ZodCnAzQB/LyLW+5 gTyccDilQQeGUV+l9l4Q2AbfpyP7bYWl7pdAF+K94nnBImAhsTjpnyhMmAeCxo19YHTK BGt3YCLeyNnghCNYIIksmcYkmLc8vwBn2rjL9eofjIfymx86dgNz8Gj9m0qRNQO+G6Ia 7Oz4kxwYVNfWiiwJQx8qZV9O7MsNhwOMza6Mf/OwhuagQ/7XuJ+KzAhE7PdhgTcKrrmH BZRw== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of hdanton@sina.com designates 202.108.7.213 as permitted sender) smtp.mailfrom=hdanton@sina.com X-Gm-Message-State: APjAAAVQbRu2Z6gnnWqhKa9reP8bs3G6Z1NBjIatljJa2JvwlCTkof0i uj2M6cOi0hfh2/cwxMqFrY66+a8vHrdA36QDDh19KHjlmBRQoOp4Sm9LelCJNIoMoQBggPVuA5T jlxoG/MA8xb2Oweh/fhHAlLahDXCvIzxaLIDXuwRtjZD9gfrodFWEAeLFFzDimXv8qw== X-Received: by 2002:aa7:9786:: with SMTP id o6mr49880579pfp.222.1564633373887; Wed, 31 Jul 2019 21:22:53 -0700 (PDT) X-Google-Smtp-Source: APXvYqz4kF8B95CGj+s8zKYWKMjwufz+nop0rfmew2tp7hWM+CDFD5zMasIaO+65bFoarsL86vd3 X-Received: by 2002:aa7:9786:: with SMTP id o6mr49880542pfp.222.1564633373212; Wed, 31 Jul 2019 21:22:53 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1564633373; cv=none; d=google.com; s=arc-20160816; b=tQi4hbVHG2e+iYHDqyQYxb4Ji64HqdIPIUpIZYi3LRiTdbXxLrmylbqk6tpfIivcec ye72s64Squz6Dj9NdSB2m0Yi1tFA3en+WSf43shidTb808K+qMqRVEUtPxX7vtgHzzAL EfeXBVSuT3+uiWqbYE32oRsHzeXiDJcZ24FCeX55RTL4Aiv8SMedeu2r9txAJHTf2Mgx bTjmgEWc6MhNoHs+Ejhxwz9ZnaUdNKKR0unk6LMOCVBT9v/3WaBgpp3cgC1KYd0jHcEo 5aCmWLmAg3ZffO+6+tvJMGlloNp/jQF1PePXuHNkRbowikYv6KZixZAjYnL2AfGQ8IUT sbJw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:list-post:list-archive:archived-at :list-id:precedence:content-language:mime-version:user-agent :references:in-reply-to:message-id:date:subject:cc:to:from; bh=YWQfKGIde2FQKMsI9cImY1CNyF8U748+3m93N97mArI=; b=1Bolo/hiyWOdLzpQfGGn+1bN4M17SR9YMV4Q8zfqNp5upwk9kSXSXGSuX2qMG1pepH /OlVheEm286pvi2F0bs298wfXovxo2ZGyVzrhir9pQyEemMTL4TYNhbBrfecmXSNRXsm 7VNI1LHXEblJJZV+MI3nUjOcWadqSKkBfOSGw6ue0buB5DyMM+wbRIaSr6AN3Br7L0SI vpQtoCi/JKOykYkc6FgPmxwm6AnV/oqwFDv+yEeuUE8fgizPz7tT7SsilhFDlVjw3GGN rDmN20QhrXE3h1TGO6a+XQoAg2wl3wHus8FE3H1/HKBYdfzsoCfPZRJ1wcQOQCrtcMMr zmjw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of hdanton@sina.com designates 202.108.7.213 as permitted sender) smtp.mailfrom=hdanton@sina.com Received: from mail7-213.sinamail.sina.com.cn (mail7-213.sinamail.sina.com.cn. [202.108.7.213]) by mx.google.com with SMTP id a19si37619504pgw.234.2019.07.31.21.22.52 for ; Wed, 31 Jul 2019 21:22:53 -0700 (PDT) Received-SPF: pass (google.com: domain of hdanton@sina.com designates 202.108.7.213 as permitted sender) client-ip=202.108.7.213; Authentication-Results: mx.google.com; spf=pass (google.com: domain of hdanton@sina.com designates 202.108.7.213 as permitted sender) smtp.mailfrom=hdanton@sina.com Received: from unknown (HELO localhost.localdomain)([222.131.77.31]) by sina.com with ESMTP id 5D42691900004DEA; Thu, 1 Aug 2019 12:22:51 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com X-SMAIL-MID: 26952250201762 From: Hillf Danton To: Mike Kravetz Cc: Vlastimil Babka , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko , Johannes Weiner , Andrew Morton Subject: Re: [RFC PATCH 1/3] mm, reclaim: make should_continue_reclaim perform dryrun detection Date: Thu, 1 Aug 2019 12:22:40 +0800 Message-Id: In-Reply-To: <295a37b1-8257-9b4a-b586-9a4990cc9d35@suse.cz> References: <20190724175014.9935-1-mike.kravetz@oracle.com> <20190724175014.9935-2-mike.kravetz@oracle.com> <20190725080551.GB2708@suse.de> <295a37b1-8257-9b4a-b586-9a4990cc9d35@suse.cz> User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Language: en-US List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Archived-At: List-Archive: List-Post: Content-Transfer-Encoding: 8bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000008, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Message-ID: <20190801042240.J5_QWR8RtBnRI3AikCWC67iK8-3xY6p246pjxX4Nqbg@z> On Wed, 31 Jul 2019 14:11:02 -0700 Mike Kravetz wrote: > > On 7/31/19 4:08 AM, Vlastimil Babka wrote: > > > > I agree this is an improvement overall, but perhaps the patch does too > > many things at once. The reshuffle is one thing and makes sense. The > > change of the last return condition could perhaps be separate. Also > > AFAICS the ultimate result is that when nr_reclaimed == 0, the function > > will now always return false. Which makes the initial test for > > __GFP_RETRY_MAYFAIL and the comments there misleading. There will no > > longer be a full LRU scan guaranteed - as long as the scanned LRU chunk > > yields no reclaimed page, we abort. > > Can someone help me understand why nr_scanned == 0 guarantees a full > LRU scan? AFAIC no pages reclaimed without pages scanned(no scanning no reclaiming). Literally a reclaimer's KPI is usually gauged by its effeicency of reclaiming pages, irrespective of factors like the proportion of dirty pages, costly order, the online of a swap disk and lru size. At the moment nr_scanned == 0 raises a red light and the reclaimer has to take right actions accordingly. Currently there is no ruleout of a full lru scan. Feel free to correct me if anything missing. Hillf