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[141.146.126.78]) by mx.google.com with ESMTPS id q203si4347142qke.253.2019.08.05.18.48.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Aug 2019 18:48:10 -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=D8oNjiVe; 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 x761jJ5f152854; Tue, 6 Aug 2019 01:48:06 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=corp-2018-07-02; bh=fr5eyPRRWPi1rDqCT8/skQQ0aW1iOdHkBGzG8QNDcy4=; b=D8oNjiVeBbBG2MWiIYLecowUjrtkG6Oal3VR7bQ6Tq4XmhC3HUSvX6hveVydUDg+uCSf fKsU20yt/rHoLw6ROp/IekRVGI4s/cWGUmKBSV7E8/r7r/O2wc1tbqncE7nR6+Yu66hj 1qJvG2d/5kbJSHgu3Un/N1D+KaOJXSGD1SzDh7SVXW6cfVCl6R6JAnJFoc4vKwwNQlqN s9Hb0KVzO9OZdGzBATWoa1/t84ZevYXdnjOvmoB7ZbtVUdiJTy5OA7qOqvWX8RaT+UkC 9v6Wrar1BRo08b+nRfu68R4Ga8X0BI0eFRjdsT+zcX2559xT3mapK8BHVejeI9Dkppus Ag== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by aserp2120.oracle.com with ESMTP id 2u527pjm9r-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 06 Aug 2019 01:48:06 +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 x761m4bW086383; Tue, 6 Aug 2019 01:48:05 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userp3020.oracle.com with ESMTP id 2u51kn4a0w-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 06 Aug 2019 01:48:05 +0000 Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x761ludm016081; Tue, 6 Aug 2019 01:47:56 GMT Received: from monkey.oracle.com (/71.63.128.209) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 05 Aug 2019 18:47:55 -0700 From: Mike Kravetz To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Hillf Danton , Vlastimil Babka , Michal Hocko , Mel Gorman , Johannes Weiner , Andrea Arcangeli , David Rientjes , Andrew Morton , Mike Kravetz Subject: [PATCH v2 2/4] mm, reclaim: cleanup should_continue_reclaim() Date: Mon, 5 Aug 2019 18:47:42 -0700 Message-Id: <20190806014744.15446-3-mike.kravetz@oracle.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190806014744.15446-1-mike.kravetz@oracle.com> References: <20190806014744.15446-1-mike.kravetz@oracle.com> MIME-Version: 1.0 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-1908060020 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=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-1908060019 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: X-Virus-Scanned: ClamAV using ClamSMTP From: Vlastimil Babka After commit "mm, reclaim: make should_continue_reclaim perform dryrun detection", closer look at the function shows, that nr_reclaimed == 0 means the function will always return false. And since non-zero nr_reclaimed implies non_zero nr_scanned, testing nr_scanned serves no purpose, and so does the testing for __GFP_RETRY_MAYFAIL. This patch thus cleans up the function to test only !nr_reclaimed upfront, and remove the __GFP_RETRY_MAYFAIL test and nr_scanned parameter completely. Comment is also updated, explaining that approximating "full LRU list has been scanned" with nr_scanned == 0 didn't really work. Signed-off-by: Vlastimil Babka Acked-by: Mike Kravetz Signed-off-by: Mike Kravetz --- Commit message reformatted to avoid line wrap. mm/vmscan.c | 43 ++++++++++++++----------------------------- 1 file changed, 14 insertions(+), 29 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index a386c5351592..227d10cd704b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2704,7 +2704,6 @@ static bool in_reclaim_compaction(struct scan_control *sc) */ static inline bool should_continue_reclaim(struct pglist_data *pgdat, unsigned long nr_reclaimed, - unsigned long nr_scanned, struct scan_control *sc) { unsigned long pages_for_compaction; @@ -2715,28 +2714,18 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, if (!in_reclaim_compaction(sc)) return false; - /* Consider stopping depending on scan and reclaim activity */ - if (sc->gfp_mask & __GFP_RETRY_MAYFAIL) { - /* - * For __GFP_RETRY_MAYFAIL allocations, stop reclaiming if the - * full LRU list has been scanned and we are still failing - * to reclaim pages. This full LRU scan is potentially - * expensive but a __GFP_RETRY_MAYFAIL caller really wants to succeed - */ - if (!nr_reclaimed && !nr_scanned) - return false; - } else { - /* - * For non-__GFP_RETRY_MAYFAIL allocations which can presumably - * fail without consequence, stop if we failed to reclaim - * any pages from the last SWAP_CLUSTER_MAX number of - * pages that were scanned. This will return to the - * caller faster at the risk reclaim/compaction and - * the resulting allocation attempt fails - */ - if (!nr_reclaimed) - return false; - } + /* + * Stop if we failed to reclaim any pages from the last SWAP_CLUSTER_MAX + * number of pages that were scanned. This will return to the caller + * with the risk reclaim/compaction and the resulting allocation attempt + * fails. In the past we have tried harder for __GFP_RETRY_MAYFAIL + * allocations through requiring that the full LRU list has been scanned + * first, by assuming that zero delta of sc->nr_scanned means full LRU + * scan, but that approximation was wrong, and there were corner cases + * where always a non-zero amount of pages were scanned. + */ + if (!nr_reclaimed) + return false; /* If compaction would go ahead or the allocation would succeed, stop */ for (z = 0; z <= sc->reclaim_idx; z++) { @@ -2763,11 +2752,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, if (get_nr_swap_pages() > 0) inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); - return inactive_lru_pages > pages_for_compaction && - /* - * avoid dryrun with plenty of inactive pages - */ - nr_scanned && nr_reclaimed; + return inactive_lru_pages > pages_for_compaction; } static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg) @@ -2936,7 +2921,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) wait_iff_congested(BLK_RW_ASYNC, HZ/10); } while (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, - sc->nr_scanned - nr_scanned, sc)); + sc)); /* * Kswapd gives up on balancing particular nodes after too