From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755144AbbH0OAK (ORCPT ); Thu, 27 Aug 2015 10:00:10 -0400 Received: from mga02.intel.com ([134.134.136.20]:19308 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755051AbbH0OAI (ORCPT ); Thu, 27 Aug 2015 10:00:08 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.17,422,1437462000"; d="scan'208";a="792019889" From: "Kirill A. Shutemov" To: Andrew Morton , Hugh Dickins Cc: Andrea Arcangeli , Dave Hansen , Vlastimil Babka , Johannes Weiner , Michal Hocko , David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" Subject: [PATCHv4 7/7] mm: use 'unsigned int' for compound_dtor/compound_order on 64BIT Date: Thu, 27 Aug 2015 16:59:21 +0300 Message-Id: <1440683961-32839-8-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1440683961-32839-1-git-send-email-kirill.shutemov@linux.intel.com> References: <1440683961-32839-1-git-send-email-kirill.shutemov@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 64 bit system we have enough space in struct page to encode compound_dtor and compound_order with unsigned int. On x86-64 it leads to slightly smaller code size due usesage of plain MOV instead of MOVZX (zero-extended move) or similar effect. allyesconfig: text data bss dec hex filename 159520446 48146736 72196096 279863278 10ae5fee vmlinux.pre 159520382 48146736 72196096 279863214 10ae5fae vmlinux.post On other architectures without native support of 16-bit data types the difference can be bigger. Signed-off-by: Kirill A. Shutemov --- include/linux/mm_types.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index ecaf3b1d0216..39b0db74ba5e 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -150,8 +150,13 @@ struct page { /* First tail page of compound page */ struct { unsigned long compound_head; /* If bit zero is set */ +#ifdef CONFIG_64BIT + unsigned int compound_dtor; + unsigned int compound_order; +#else unsigned short int compound_dtor; unsigned short int compound_order; +#endif }; #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS -- 2.5.0