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=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 4515BC433FE for ; Mon, 7 Dec 2020 09:46:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B81C2220B for ; Mon, 7 Dec 2020 09:46:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726522AbgLGJq0 (ORCPT ); Mon, 7 Dec 2020 04:46:26 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45325 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726178AbgLGJqZ (ORCPT ); Mon, 7 Dec 2020 04:46:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607334299; h=from:from: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=60RwvP6MhS9NxqDxL1ryxBLqNxzb7ws7UJi6gMrnHrQ=; b=fiqXl+TRc47Ke8YwuQa/D7powEhBQZ5PmTw1xE1SSAlobiCBsdTaCNwRf6xp4az88TLrfI +G6+MnCmzyAR7ffHTgMRAOCSlCFzpuOM0w4rUvt8jFCsObEzXpYXfwLOl9Hdy6hvIX0Q1f d4qp8gId1vy8qxK7++cty6odc5rUzfA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-293-oYJsurXhOGCLnOykFcb0pQ-1; Mon, 07 Dec 2020 04:44:55 -0500 X-MC-Unique: oYJsurXhOGCLnOykFcb0pQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A8E80107ACE8; Mon, 7 Dec 2020 09:44:53 +0000 (UTC) Received: from [10.36.114.33] (ovpn-114-33.ams2.redhat.com [10.36.114.33]) by smtp.corp.redhat.com (Postfix) with ESMTP id 501F35C1A1; Mon, 7 Dec 2020 09:44:52 +0000 (UTC) Subject: Re: [PATCH v3] mm/page_alloc: speeding up the iteration of max_order To: Muchun Song , akpm@linux-foundation.org, vbabka@suse.cz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20201204155109.55451-1-songmuchun@bytedance.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <157411c6-90ad-e99d-b75e-002783f984b1@redhat.com> Date: Mon, 7 Dec 2020 10:44:51 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201204155109.55451-1-songmuchun@bytedance.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04.12.20 16:51, Muchun Song wrote: > When we free a page whose order is very close to MAX_ORDER and greater > than pageblock_order, it wastes some CPU cycles to increase max_order > to MAX_ORDER one by one and check the pageblock migratetype of that page > repeatedly especially when MAX_ORDER is much larger than pageblock_order. > > We also should not be checking migratetype of buddy when "order == > MAX_ORDER - 1" as the buddy pfn may be invalid, so adjust the condition. > With the new check, we don't need the max_order check anymore, so we > replace it. > > Also adjust max_order initialization so that it's lower by one than > previously, which makes the code hopefully more clear. > > Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks") > Signed-off-by: Muchun Song > Acked-by: Vlastimil Babka > --- > Changes in v3: > - Update commit log. > > Changes in v2: > - Rework the code suggested by Vlastimil. Thanks. > > mm/page_alloc.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index f91df593bf71..56e603eea1dd 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1002,7 +1002,7 @@ static inline void __free_one_page(struct page *page, > struct page *buddy; > bool to_tail; > > - max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1); > + max_order = min_t(unsigned int, MAX_ORDER - 1, pageblock_order); > > VM_BUG_ON(!zone_is_initialized(zone)); > VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page); > @@ -1015,7 +1015,7 @@ static inline void __free_one_page(struct page *page, > VM_BUG_ON_PAGE(bad_range(zone, page), page); > > continue_merging: > - while (order < max_order - 1) { > + while (order < max_order) { > if (compaction_capture(capc, page, order, migratetype)) { > __mod_zone_freepage_state(zone, -(1 << order), > migratetype); > @@ -1041,7 +1041,7 @@ static inline void __free_one_page(struct page *page, > pfn = combined_pfn; > order++; > } > - if (max_order < MAX_ORDER) { > + if (order < MAX_ORDER - 1) { > /* If we are here, it means order is >= pageblock_order. > * We want to prevent merge between freepages on isolate > * pageblock and normal pageblock. Without this, pageblock > @@ -1062,7 +1062,7 @@ static inline void __free_one_page(struct page *page, > is_migrate_isolate(buddy_mt))) > goto done_merging; > } > - max_order++; > + max_order = order + 1; > goto continue_merging; > } > > LGTM Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb