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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 49E6BC0650F for ; Mon, 5 Aug 2019 08:43:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23171217D9 for ; Mon, 5 Aug 2019 08:43:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727798AbfHEInB (ORCPT ); Mon, 5 Aug 2019 04:43:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:56926 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726454AbfHEInB (ORCPT ); Mon, 5 Aug 2019 04:43:01 -0400 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 D5442B61C; Mon, 5 Aug 2019 08:42:59 +0000 (UTC) Subject: Re: [PATCH 1/3] mm, reclaim: make should_continue_reclaim perform dryrun detection To: Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Hillf Danton , Michal Hocko , Mel Gorman , Johannes Weiner , Andrea Arcangeli , David Rientjes , Andrew Morton References: <20190802223930.30971-1-mike.kravetz@oracle.com> <20190802223930.30971-2-mike.kravetz@oracle.com> From: Vlastimil Babka Openpgp: preference=signencrypt Autocrypt: addr=vbabka@suse.cz; prefer-encrypt=mutual; keydata= mQINBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 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xVKRSg3I2m+DUTVqBy7Lixo73hnW69kSjtqCeamY/NSu6LNP+b0wAOKhwz9hBEwEHLp05+mj 5ZFJyfGsOiNUcMoO/17FO4EBxSDP3FDLllpuzlFD7SXkfJaMWYmXIlO0jLzdfwfcnDzBbPwO hBM8hvtsyq8lq8vJOxv6XD6xcTtj5Az8t2JjdUX6SF9hxJpwhBU0wrCoGDkWp4Bbv6jnF7zP Nzftr4l8RuJoywDIiJpdaNpSlXKpj/K6KrnyAI/joYc7 Message-ID: Date: Mon, 5 Aug 2019 10:42:59 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190802223930.30971-2-mike.kravetz@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/3/19 12:39 AM, Mike Kravetz wrote: > From: Hillf Danton > > Address the issue of should_continue_reclaim continuing true too often > for __GFP_RETRY_MAYFAIL attempts when !nr_reclaimed and nr_scanned. > This could happen during hugetlb page allocation causing stalls for > minutes or hours. > > We can stop reclaiming pages if compaction reports it can make a progress. > A code reshuffle is needed to do that. > And it has side-effects, however, > with allocation latencies in other cases but that would come at the cost > of potential premature reclaim which has consequences of itself. Based on Mel's longer explanation, can we clarify the wording here? e.g.: There might be side-effect for other high-order allocations that would potentially benefit from more reclaim before compaction for them to be faster and less likely to stall, but the consequences of premature/over-reclaim are considered worse. > We can also bail out of reclaiming pages if we know that there are not > enough inactive lru pages left to satisfy the costly allocation. > > We can give up reclaiming pages too if we see dryrun occur, with the > certainty of plenty of inactive pages. IOW with dryrun detected, we are > sure we have reclaimed as many pages as we could. > > Cc: Mike Kravetz > Cc: Mel Gorman > Cc: Michal Hocko > Cc: Vlastimil Babka > Cc: Johannes Weiner > Signed-off-by: Hillf Danton > Tested-by: Mike Kravetz > Acked-by: Mel Gorman Acked-by: Vlastimil Babka I will send some followup cleanup. There should be also Mike's SOB? > --- > mm/vmscan.c | 28 +++++++++++++++------------- > 1 file changed, 15 insertions(+), 13 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 47aa2158cfac..a386c5351592 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2738,18 +2738,6 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, > return false; > } > > - /* > - * If we have not reclaimed enough pages for compaction and the > - * inactive lists are large enough, continue reclaiming > - */ > - pages_for_compaction = compact_gap(sc->order); > - inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); > - if (get_nr_swap_pages() > 0) > - inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); > - if (sc->nr_reclaimed < pages_for_compaction && > - inactive_lru_pages > pages_for_compaction) > - return true; > - > /* If compaction would go ahead or the allocation would succeed, stop */ > for (z = 0; z <= sc->reclaim_idx; z++) { > struct zone *zone = &pgdat->node_zones[z]; > @@ -2765,7 +2753,21 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, > ; > } > } > - return true; > + > + /* > + * If we have not reclaimed enough pages for compaction and the > + * inactive lists are large enough, continue reclaiming > + */ > + pages_for_compaction = compact_gap(sc->order); > + inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); > + 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; > } > > static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg) >