From patchwork Tue Sep 1 02:50:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alex Shi X-Patchwork-Id: 11747257 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0990114E5 for ; Tue, 1 Sep 2020 02:50:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D5363207EA for ; Tue, 1 Sep 2020 02:50:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D5363207EA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A03346B005C; Mon, 31 Aug 2020 22:50:31 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 9B3146B005D; Mon, 31 Aug 2020 22:50:31 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8A3716B0062; Mon, 31 Aug 2020 22:50:31 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0151.hostedemail.com [216.40.44.151]) by kanga.kvack.org (Postfix) with ESMTP id 6F0B46B005C for ; Mon, 31 Aug 2020 22:50:31 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 2F5501DF7 for ; Tue, 1 Sep 2020 02:50:31 +0000 (UTC) X-FDA: 77212964262.25.cup23_610e3d727094 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id E50CC1804E3A8 for ; Tue, 1 Sep 2020 02:50:30 +0000 (UTC) X-Spam-Summary: 1,0,0,feba510af42fa1f9,d41d8cd98f00b204,alex.shi@linux.alibaba.com,,RULES_HIT:41:355:379:421:541:800:960:973:988:989:1260:1261:1345:1359:1431:1437:1534:1541:1711:1730:1747:1777:1792:2393:2559:2562:2693:2740:3138:3139:3140:3141:3142:3352:3865:3867:3868:3870:3871:3872:4321:4605:5007:6261:6630:8603:10004:11026:11232:11473:11658:11914:12043:12296:12297:12438:12555:12895:12986:13069:13161:13229:13311:13357:13846:14096:14181:14384:14394:14721:21060:21080:21222:21451:21627:30054,0,RBL:115.124.30.132:@linux.alibaba.com:.lbl8.mailshell.net-62.20.2.100 64.201.201.201;04yfpnb39bcutpotz7zjwk1iwhy5zocfhrcjuwtyzxy4kf1kiorbdmjqyxuw35p.r8raane3f4x6nfzkskwscnx1fdg7q516sqbt3km1y3m7ut3bbnxnurkyd181dw9.y-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:25,LUA_SUMMARY:none X-HE-Tag: cup23_610e3d727094 X-Filterd-Recvd-Size: 2957 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) by imf34.hostedemail.com (Postfix) with ESMTP for ; Tue, 1 Sep 2020 02:50:28 +0000 (UTC) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01419;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0U7Txrtg_1598928621; Received: from aliy80.localdomain(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0U7Txrtg_1598928621) by smtp.aliyun-inc.com(127.0.0.1); Tue, 01 Sep 2020 10:50:22 +0800 From: Alex Shi To: Anshuman Khandual , David Hildenbrand , Matthew Wilcox Cc: Andrew Morton , Mel Gorman , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 2/3] mm/pageblock: remove false sharing in pageblock_flags Date: Tue, 1 Sep 2020 10:50:11 +0800 Message-Id: <1598928612-68996-2-git-send-email-alex.shi@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1598928612-68996-1-git-send-email-alex.shi@linux.alibaba.com> References: <1598928612-68996-1-git-send-email-alex.shi@linux.alibaba.com> X-Rspamd-Queue-Id: E50CC1804E3A8 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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: Current pageblock_flags is only 4 bits, so it has to share a char size in cmpxchg when get set, the false sharing cause perf drop. If we incrase the bits up to 8, false sharing would gone in cmpxchg. and the only cost is half char per pageblock, which is half char per 128MB on x86, 4 chars in 1 GB. Signed-off-by: Alex Shi Cc: Andrew Morton Cc: Mel Gorman Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org --- include/linux/pageblock-flags.h | 2 +- mm/page_alloc.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h index d189441568eb..f785c9d6d68c 100644 --- a/include/linux/pageblock-flags.h +++ b/include/linux/pageblock-flags.h @@ -25,7 +25,7 @@ enum pageblock_bits { * Assume the bits will always align on a word. If this assumption * changes then get/set pageblock needs updating. */ - NR_PAGEBLOCK_BITS + NR_PAGEBLOCK_BITS = BITS_PER_BYTE }; #ifdef CONFIG_HUGETLB_PAGE diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 81e96d4d9c42..60342e764090 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -517,7 +517,7 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, unsigned long bitidx, byte_bitidx; unsigned char old_byte, byte; - BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); + BUILD_BUG_ON(NR_PAGEBLOCK_BITS != BITS_PER_BYTE); BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits)); bitmap = get_pageblock_bitmap(page, pfn);