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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 4C279C433C1 for ; Fri, 19 Mar 2021 18:18:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8DB096195F for ; Fri, 19 Mar 2021 18:18:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8DB096195F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1C7196B0073; Fri, 19 Mar 2021 14:18:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 176E26B0074; Fri, 19 Mar 2021 14:18:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F34EC8D0001; Fri, 19 Mar 2021 14:18:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0104.hostedemail.com [216.40.44.104]) by kanga.kvack.org (Postfix) with ESMTP id D1DA16B0073 for ; Fri, 19 Mar 2021 14:18:44 -0400 (EDT) Received: from smtpin31.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 80EC21821E9B4 for ; Fri, 19 Mar 2021 18:18:44 +0000 (UTC) X-FDA: 77937434568.31.24522CB Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf13.hostedemail.com (Postfix) with ESMTP id A2648E0003A9 for ; Fri, 19 Mar 2021 18:18:39 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 082F6AC23; Fri, 19 Mar 2021 18:18:33 +0000 (UTC) To: Mel Gorman , Andrew Morton Cc: Chuck Lever , Jesper Dangaard Brouer , Christoph Hellwig , Alexander Duyck , Matthew Wilcox , LKML , Linux-Net , Linux-MM , Linux-NFS References: <20210312154331.32229-1-mgorman@techsingularity.net> <20210312154331.32229-4-mgorman@techsingularity.net> From: Vlastimil Babka Subject: Re: [PATCH 3/7] mm/page_alloc: Add a bulk page allocator Message-ID: <7c520bbb-efd7-7cad-95df-610000832a67@suse.cz> Date: Fri, 19 Mar 2021 19:18:32 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210312154331.32229-4-mgorman@techsingularity.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: A2648E0003A9 X-Stat-Signature: 38h6ubwg54hn65czwogzqdsnruchkqkz Received-SPF: none (suse.cz>: No applicable sender policy available) receiver=imf13; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: none/none X-HE-Tag: 1616177919-4160 Content-Transfer-Encoding: quoted-printable 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 3/12/21 4:43 PM, Mel Gorman wrote: > This patch adds a new page allocator interface via alloc_pages_bulk, > and __alloc_pages_bulk_nodemask. A caller requests a number of pages > to be allocated and added to a list. They can be freed in bulk using > free_pages_bulk(). >=20 > The API is not guaranteed to return the requested number of pages and > may fail if the preferred allocation zone has limited free memory, the > cpuset changes during the allocation or page debugging decides to fail > an allocation. It's up to the caller to request more pages in batch > if necessary. >=20 > Note that this implementation is not very efficient and could be improv= ed > but it would require refactoring. The intent is to make it available ea= rly > to determine what semantics are required by different callers. Once the > full semantics are nailed down, it can be refactored. >=20 > Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka Although maybe premature, if it changes significantly due to the users' performance feedback, let's see :) Some nits below: ... > @@ -4963,6 +4978,107 @@ static inline bool prepare_alloc_pages(gfp_t gf= p, unsigned int order, > return true; > } > =20 > +/* > + * This is a batched version of the page allocator that attempts to > + * allocate nr_pages quickly from the preferred zone and add them to l= ist. > + * > + * Returns the number of pages allocated. > + */ > +int __alloc_pages_bulk(gfp_t gfp, int preferred_nid, > + nodemask_t *nodemask, int nr_pages, > + struct list_head *alloc_list) > +{ > + struct page *page; > + unsigned long flags; > + struct zone *zone; > + struct zoneref *z; > + struct per_cpu_pages *pcp; > + struct list_head *pcp_list; > + struct alloc_context ac; > + gfp_t alloc_gfp; > + unsigned int alloc_flags; > + int allocated =3D 0; > + > + if (WARN_ON_ONCE(nr_pages <=3D 0)) > + return 0; > + > + if (nr_pages =3D=3D 1) > + goto failed; > + > + /* May set ALLOC_NOFRAGMENT, fragmentation will return 1 page. */ > + if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, > + &alloc_gfp, &alloc_flags)) Unusual identation here. > + return 0; > + gfp =3D alloc_gfp; > + > + /* Find an allowed local zone that meets the high watermark. */ > + for_each_zone_zonelist_nodemask(zone, z, ac.zonelist, ac.highest_zone= idx, ac.nodemask) { > + unsigned long mark; > + > + if (cpusets_enabled() && (alloc_flags & ALLOC_CPUSET) && > + !__cpuset_zone_allowed(zone, gfp)) { > + continue; > + } > + > + if (nr_online_nodes > 1 && zone !=3D ac.preferred_zoneref->zone && > + zone_to_nid(zone) !=3D zone_to_nid(ac.preferred_zoneref->zone)) = { > + goto failed; > + } > + > + mark =3D wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_page= s; > + if (zone_watermark_fast(zone, 0, mark, > + zonelist_zone_idx(ac.preferred_zoneref), > + alloc_flags, gfp)) { > + break; > + } > + } > + if (!zone) > + return 0; Why not also "goto failed;" here?