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=-20.2 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,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 999DCC433EF for ; Mon, 20 Sep 2021 17:34:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 83A196337D for ; Mon, 20 Sep 2021 17:34:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346453AbhITRfd (ORCPT ); Mon, 20 Sep 2021 13:35:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:36656 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346328AbhITRdK (ORCPT ); Mon, 20 Sep 2021 13:33:10 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2060A61AFE; Mon, 20 Sep 2021 17:05:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632157511; bh=eP7Li2TkgWouh3qvmuCojlEu/nzW8BXuiaLwkBemdrk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lL67lf1o5kHiKt1MLRlQlj1RHioSxlYb0eGZRQDNC0ZdOlt/hbqXrEOpJxsDOTMbx snF7DF0HjuTdyfthmITD+gd1AjZ/UrrDJgAjEBdUnhDpKjjKPoCr9dPRglnzcv68gV 0C7/aR0pd9OPGXtMMHwMaBOJRF4RT47h3WLMW8xY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Muchun Song , Vlastimil Babka , Oscar Salvador , David Hildenbrand , Andrew Morton , Linus Torvalds Subject: [PATCH 4.19 024/293] mm/page_alloc: speed up the iteration of max_order Date: Mon, 20 Sep 2021 18:39:46 +0200 Message-Id: <20210920163934.092672861@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210920163933.258815435@linuxfoundation.org> References: <20210920163933.258815435@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Muchun Song commit 7ad69832f37e3cea8557db6df7c793905f1135e8 upstream. 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. Link: https://lkml.kernel.org/r/20201204155109.55451-1-songmuchun@bytedance.com Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks") Signed-off-by: Muchun Song Acked-by: Vlastimil Babka Reviewed-by: Oscar Salvador Reviewed-by: David Hildenbrand Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -807,7 +807,7 @@ static inline void __free_one_page(struc struct page *buddy; unsigned int max_order; - 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); @@ -820,7 +820,7 @@ static inline void __free_one_page(struc VM_BUG_ON_PAGE(bad_range(zone, page), page); continue_merging: - while (order < max_order - 1) { + while (order < max_order) { buddy_pfn = __find_buddy_pfn(pfn, order); buddy = page + (buddy_pfn - pfn); @@ -844,7 +844,7 @@ continue_merging: 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 @@ -865,7 +865,7 @@ continue_merging: is_migrate_isolate(buddy_mt))) goto done_merging; } - max_order++; + max_order = order + 1; goto continue_merging; }