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[141.146.126.78]) by mx.google.com with ESMTPS id d21si9220005qto.3.2019.08.05.14.44.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Aug 2019 14:44:52 -0700 (PDT) Received-SPF: pass (google.com: domain of daniel.m.jordan@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=roDAct70; spf=pass (google.com: domain of daniel.m.jordan@oracle.com designates 141.146.126.78 as permitted sender) smtp.mailfrom=daniel.m.jordan@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 x75LiKM7173657; Mon, 5 Aug 2019 21:44:40 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=tUOx2J5+IqGOok0vsUKMad0tL7ZdRLzF7oPP2HBvWO8=; b=roDAct70rERrM9LJeZpTB0ALEj6JmUbx9r2BUDe9eYkRwnu4cbDthpksWZnaMsWPQqSl X8bCxZNg1D5jgMxBICmBA6HCxH60Ea45b2jNIoqtFR8JuLSaVs4Jg+YJ0ASHx4QthPq/ ykCipDJOKswNvVZt8SwaIEiefVw02cByNX74uWxQ6UcOm6ocxIttnvw9V0//k1ItGPER 9NLSZeqeqLdrVRd/+Bv+K0MGmtGin7OifIdzeoPkGiOGZUYk7FL+05e73rulgijApQH3 MZaE39spfNmOBJzsaWUsTkSSmJ5PgKZcvx48jZNDlbpKGbWDKoer6ZFc4fH1//1uOO5l 9g== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by aserp2120.oracle.com with ESMTP id 2u527phue0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 05 Aug 2019 21:44:40 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x75Lgxhr024688; Mon, 5 Aug 2019 21:44:39 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3020.oracle.com with ESMTP id 2u51kmxmfy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 05 Aug 2019 21:44:39 +0000 Received: from abhmp0010.oracle.com (abhmp0010.oracle.com [141.146.116.16]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x75LiZW3027456; Mon, 5 Aug 2019 21:44:35 GMT Received: from ca-dmjordan1.us.oracle.com (/10.211.9.48) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 05 Aug 2019 14:44:35 -0700 Date: Mon, 5 Aug 2019 17:44:31 -0400 From: Daniel Jordan To: Yafang Shao Cc: akpm@linux-foundation.org, linux-mm@kvack.org, Michal Hocko , Yafang Shao , Mel Gorman , Christoph Lameter Subject: Re: [PATCH RESEND] mm/vmscan: shrink slab in node reclaim Message-ID: <20190805214219.fxida5zojihauo7d@ca-dmjordan1.us.oracle.com> References: <1564538401-21353-1-git-send-email-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1564538401-21353-1-git-send-email-laoar.shao@gmail.com> User-Agent: NeoMutt/20180716 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9340 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-1908050219 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9340 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=1011 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-1908050219 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: Hi Yafang, On Tue, Jul 30, 2019 at 10:00:01PM -0400, Yafang Shao wrote: > In the node reclaim, may_shrinkslab is 0 by default, > hence shrink_slab will never be performed in it. > While shrik_slab should be performed if the relcaimable slab is over > min slab limit. Nice catch, I think this needs Fixes: 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs") > If reclaimable pagecache is less than min_unmapped_pages while > reclaimable slab is greater than min_slab_pages, we only shrink slab. > Otherwise the min_unmapped_pages will be useless under this condition. > A new bitmask no_pagecache is introduced in scan_control for this > purpose, which is 0 by default. > Once __node_reclaim() is called, either the reclaimable pagecache is > greater than min_unmapped_pages or reclaimable slab is greater than > min_slab_pages, that is ensured in function node_reclaim(). So wen can > remove the if statement in __node_reclaim(). Why is the if statement there to begin with then, if the condition has already been checked in node_reclaim? Looks like it came in with 0ff38490c836 ("[PATCH] zone_reclaim: dynamic slab reclaim"), but it's not obvious to me why. Maybe Christoph remembers. I found this part of the changelog kind of hard to parse. This instead instead of above block? Add scan_control::no_pagecache so shrink_node can decide to reclaim page cache, slab, or both as dictated by min_unmapped_pages and min_slab_pages. shrink_node will do at least one of the two because otherwise node_reclaim returns early. Maybe start the next paragraph with __node_reclaim can detect when enough slab has been reclaimed because... > sc.reclaim_state.reclaimed_slab will tell us how many pages are > reclaimed in shrink slab. ... > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 47aa215..1e410ef 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -91,6 +91,9 @@ struct scan_control { > /* e.g. boosted watermark reclaim leaves slabs alone */ > unsigned int may_shrinkslab:1; > > + /* in node relcaim mode, we may shrink slab only */ reclaim > @@ -4268,6 +4273,10 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in > .may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE), > .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP), > .may_swap = 1, > + .may_shrinkslab = (node_page_state(pgdat, NR_SLAB_RECLAIMABLE) > > + pgdat->min_slab_pages), > + .no_pagecache = !(node_pagecache_reclaimable(pgdat) > > + pgdat->min_unmapped_pages), It's less awkward to do away with the ! and invert the condition.