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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2AFEC61D9C for ; Wed, 22 Nov 2023 10:26:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 751866B05E1; Wed, 22 Nov 2023 05:26:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 701366B05E3; Wed, 22 Nov 2023 05:26:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 617226B05E4; Wed, 22 Nov 2023 05:26:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 51EF16B05E1 for ; Wed, 22 Nov 2023 05:26:37 -0500 (EST) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 1F17216083E for ; Wed, 22 Nov 2023 10:26:37 +0000 (UTC) X-FDA: 81485211234.15.66F0BF3 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf13.hostedemail.com (Postfix) with ESMTP id D5FA82002C for ; Wed, 22 Nov 2023 10:26:34 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=none; spf=pass (imf13.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1700648795; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yrXLFt5w2YBxERsGkGrWkxzrUydGO4NOofx/2occdOg=; b=bDE9GyaCgjhjvDHavuXJoGqMd+XCtvftO3Iz3EmSUlV1/KYf8b+9YdBFf0xcLhCzou/aYB am/deVkfuUeTmMntRRrEftof5+vAGekjeq3ENtgDeiEKQcyJYfP728pPV80E/SAdlaGW1l JdEXGB9h/Dh3t70nK0TLYews1R/Knzs= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=none; spf=pass (imf13.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1700648795; a=rsa-sha256; cv=none; b=TXHQgwofMveJvPut81zNjwNp3jWe6pogUwEfC2M1li5MSGvfXoD1weOzVAlDLJEMXaAC6j AeD0/BfUra/GKK6DIIcjlPEtBMTdu15ejUKUqk0VCdBRt1oHNxhWOt/u2e52mZe0RDkgwE f5vojTwmjEMgRfv1W7V2gun/JJupRpI= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 891551595; Wed, 22 Nov 2023 02:27:20 -0800 (PST) Received: from [10.57.71.201] (unknown [10.57.71.201]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4340D3F6C4; Wed, 22 Nov 2023 02:26:31 -0800 (PST) Message-ID: Date: Wed, 22 Nov 2023 10:26:29 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 3/4] mm/compaction: optimize >0 order folio compaction with free page split. Content-Language: en-GB To: Zi Yan , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: "Huang, Ying" , Andrew Morton , "Matthew Wilcox (Oracle)" , David Hildenbrand , "Yin, Fengwei" , Yu Zhao , Vlastimil Babka , "Kirill A . Shutemov" , Johannes Weiner , Baolin Wang , Kemeng Shi , Mel Gorman , Rohan Puri , Mcgrof Chamberlain , Adam Manzanares , "Vishal Moola (Oracle)" References: <20231113170157.280181-1-zi.yan@sent.com> <20231113170157.280181-4-zi.yan@sent.com> From: Ryan Roberts In-Reply-To: <20231113170157.280181-4-zi.yan@sent.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D5FA82002C X-Rspam-User: X-Stat-Signature: c3o4tswburqixg49myjfu43x15djqdr5 X-Rspamd-Server: rspam01 X-HE-Tag: 1700648794-396326 X-HE-Meta: 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 rGydk6jW QQ1g+StSWcJ1VnAdH3/Yy4Ai5pw8l1t847MPAPUGvAabE4OLKGUrKQe067MidmeQC5MNSb8H+8/tOnYTd2ZTXz7shteS3ixOdm8JICrs97hN6xRiyHaBmDMS2vw965IcEAwh1Mi4jhmjUb5chIlLpD4Ejy4Y42lYfuAZiUGXvwggsYZgHc+sRKwNlR+cmUVokfmeWeYcxetc7Nsi9KKj/kZthDbn9GPvqIUTteGhqb6pNEdYAPAzClUEK8Q== 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: List-Subscribe: List-Unsubscribe: On 13/11/2023 17:01, Zi Yan wrote: > From: Zi Yan > > During migration in a memory compaction, free pages are placed in an array > of page lists based on their order. But the desired free page order (i.e., > the order of a source page) might not be always present, thus leading to > migration failures. Split a high order free pages when source migration > page has a lower order to increase migration successful rate. > > Note: merging free pages when a migration fails and a lower order free > page is returned via compaction_free() is possible, but there is too much > work. Since the free pages are not buddy pages, it is hard to identify > these free pages using existing PFN-based page merging algorithm. > > Signed-off-by: Zi Yan > --- > mm/compaction.c | 40 +++++++++++++++++++++++++++++++++++++++- > 1 file changed, 39 insertions(+), 1 deletion(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index ec6b5cc7e907..9c083e6b399a 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1806,9 +1806,46 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) > struct compact_control *cc = (struct compact_control *)data; > struct folio *dst; > int order = folio_order(src); > + bool has_isolated_pages = false; > > +again: > if (!cc->freepages[order].nr_pages) { > - isolate_freepages(cc); > + int i; > + > + for (i = order + 1; i <= MAX_ORDER; i++) { > + if (cc->freepages[i].nr_pages) { > + struct page *freepage = > + list_first_entry(&cc->freepages[i].pages, > + struct page, lru); > + > + int start_order = i; > + unsigned long size = 1 << start_order; > + > + list_del(&freepage->lru); > + cc->freepages[i].nr_pages--; > + > + while (start_order > order) { > + start_order--; > + size >>= 1; > + > + list_add(&freepage[size].lru, > + &cc->freepages[start_order].pages); > + cc->freepages[start_order].nr_pages++; > + set_page_private(&freepage[size], start_order); > + } > + post_alloc_hook(freepage, order, __GFP_MOVABLE); > + if (order) > + prep_compound_page(freepage, order); > + dst = page_folio(freepage); > + goto done; Perhaps just do: dst = (struct folio *)freepage; goto done; then move done: up a couple of statements below, so that post_alloc_hook() and prep_compound_page() are always done below in common path? Although perhaps the cast is frowned upon, you're already making the assumption that page and folio are interchangable the way you call list_first_entry(). > + } > + } > + if (!has_isolated_pages) { > + isolate_freepages(cc); > + has_isolated_pages = true; > + goto again; > + } > + > if (!cc->freepages[order].nr_pages) > return NULL; > } > @@ -1819,6 +1856,7 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) > post_alloc_hook(&dst->page, order, __GFP_MOVABLE); > if (order) > prep_compound_page(&dst->page, order); > +done: > cc->nr_freepages -= 1 << order; > return page_rmappable_folio(&dst->page); > }