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spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728972AbeJFAhs (ORCPT ); Fri, 5 Oct 2018 20:37:48 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:47484 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727941AbeJFAhs (ORCPT ); Fri, 5 Oct 2018 20:37:48 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w95HSvEs119208; Fri, 5 Oct 2018 17:37:24 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=qu6+D26NE1pwSF+gUXBe/GMGkp8II/iqfZveB8Z213M=; b=Dtkq1nsB+AznWUv8HodlVMBlQHNDbJ7I1sj9Wst2JAngywrmw0FTjfOwxIVEpkEm659J FZRloJjNQp2cvC4dlBGos9z8XOZ7TVgUA4iwKCXF8otKaYnnL7eSz7nSJvZ0ukVsoGOf 3NjSdrXMo/bCnvfjCyDy2UgEMONQ8QjKXgWaAU01zzPUjLB8Vog6eOeoSo00aDHSrA+1 ZY3wv6NdVPY8yDlaKY5gsJFV6S86F8hDeAmzXingTxfUD3ijeYTt+7+ohi3jCNnzPjXA DtgVrDhFS8uV7T1buxKqrBcSCOn+fCBVVvWOFaWrOSuC5opFvaE3xeLiZwhwH7gaJEpD hg== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp2130.oracle.com with ESMTP id 2mt0tuc3m2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 05 Oct 2018 17:37:24 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w95HbN5D013482 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 5 Oct 2018 17:37:24 GMT Received: from abhmp0020.oracle.com (abhmp0020.oracle.com [141.146.116.26]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w95HbMCT031021; Fri, 5 Oct 2018 17:37:22 GMT Received: from [192.168.1.44] (/24.9.64.241) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 05 Oct 2018 17:37:21 +0000 Subject: Re: [mm PATCH 1/5] mm: Use mm_zero_struct_page from SPARC on all 64b architectures To: Alexander Duyck , linux-mm@kvack.org, akpm@linux-foundation.org Cc: pavel.tatashin@microsoft.com, mhocko@suse.com, dave.jiang@intel.com, linux-kernel@vger.kernel.org, willy@infradead.org, davem@davemloft.net, rppt@linux.vnet.ibm.com, vbabka@suse.cz, sparclinux@vger.kernel.org, dan.j.williams@intel.com, ldufour@linux.vnet.ibm.com, mgorman@techsingularity.net, mingo@kernel.org, kirill.shutemov@linux.intel.com References: <20181005151006.17473.83040.stgit@localhost.localdomain> <20181005151203.17473.25723.stgit@localhost.localdomain> From: Khalid Aziz Organization: Oracle Corp Message-ID: <64b4e8da-1d64-f2c1-bdbf-69dbb105e4ec@oracle.com> Date: Fri, 5 Oct 2018 11:37:17 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181005151203.17473.25723.stgit@localhost.localdomain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9037 signatures=668706 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1810050173 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/05/2018 09:12 AM, Alexander Duyck wrote: > This change makes it so that we use the same approach that was already in > use on Sparc on all the archtectures that support a 64b long. > > This is mostly motivated by the fact that 8 to 10 store/move instructions > are likely always going to be faster than having to call into a function > that is not specialized for handling page init. > > An added advantage to doing it this way is that the compiler can get away > with combining writes in the __init_single_page call. As a result the > memset call will be reduced to only about 4 write operations, or at least > that is what I am seeing with GCC 6.2 as the flags, LRU poitners, and > count/mapcount seem to be cancelling out at least 4 of the 8 assignments on > my system. > > Signed-off-by: Alexander Duyck > -- > arch/sparc/include/asm/pgtable_64.h | 30 ------------------------------ > include/linux/mm.h | 33 +++++++++++++++++++++++++++++++++ > 2 files changed, 33 insertions(+), 30 deletions(-) Looks good to me. Reviewed-by: Khalid Aziz -- Khalid > > diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h > index 1393a8ac596b..22500c3be7a9 100644 > --- a/arch/sparc/include/asm/pgtable_64.h > +++ b/arch/sparc/include/asm/pgtable_64.h > @@ -231,36 +231,6 @@ > extern struct page *mem_map_zero; > #define ZERO_PAGE(vaddr) (mem_map_zero) > > -/* This macro must be updated when the size of struct page grows above 80 > - * or reduces below 64. > - * The idea that compiler optimizes out switch() statement, and only > - * leaves clrx instructions > - */ > -#define mm_zero_struct_page(pp) do { \ > - unsigned long *_pp = (void *)(pp); \ > - \ > - /* Check that struct page is either 64, 72, or 80 bytes */ \ > - BUILD_BUG_ON(sizeof(struct page) & 7); \ > - BUILD_BUG_ON(sizeof(struct page) < 64); \ > - BUILD_BUG_ON(sizeof(struct page) > 80); \ > - \ > - switch (sizeof(struct page)) { \ > - case 80: \ > - _pp[9] = 0; /* fallthrough */ \ > - case 72: \ > - _pp[8] = 0; /* fallthrough */ \ > - default: \ > - _pp[7] = 0; \ > - _pp[6] = 0; \ > - _pp[5] = 0; \ > - _pp[4] = 0; \ > - _pp[3] = 0; \ > - _pp[2] = 0; \ > - _pp[1] = 0; \ > - _pp[0] = 0; \ > - } \ > -} while (0) > - > /* PFNs are real physical page numbers. However, mem_map only begins to record > * per-page information starting at pfn_base. This is to handle systems where > * the first physical page in the machine is at some huge physical address, > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 273d4dbd3883..a0440a6ef5cf 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -102,8 +102,41 @@ static inline void set_max_mapnr(unsigned long limit) { } > * zeroing by defining this macro in . > */ > #ifndef mm_zero_struct_page > +#if BITS_PER_LONG == 64 > +/* This function must be updated when the size of struct page grows above 80 > + * or reduces below 64. The idea that compiler optimizes out switch() > + * statement, and only leaves move/store instructions > + */ > +#define mm_zero_struct_page(pp) __mm_zero_struct_page(pp) > +static inline void __mm_zero_struct_page(struct page *page) > +{ > + unsigned long *_pp = (void *)page; > + > + /* Check that struct page is either 64, 72, or 80 bytes */ > + BUILD_BUG_ON(sizeof(struct page) & 7); > + BUILD_BUG_ON(sizeof(struct page) < 64); > + BUILD_BUG_ON(sizeof(struct page) > 80); > + > + switch (sizeof(struct page)) { > + case 80: > + _pp[9] = 0; /* fallthrough */ > + case 72: > + _pp[8] = 0; /* fallthrough */ > + default: > + _pp[7] = 0; > + _pp[6] = 0; > + _pp[5] = 0; > + _pp[4] = 0; > + _pp[3] = 0; > + _pp[2] = 0; > + _pp[1] = 0; > + _pp[0] = 0; > + } > +} > +#else > #define mm_zero_struct_page(pp) ((void)memset((pp), 0, sizeof(struct page))) > #endif > +#endif > > /* > * Default maximum number of active map areas, this limits the number of vmas >