Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751762AbdGZJun (ORCPT ); Wed, 26 Jul 2017 05:50:43 -0400 Received: from mx2.suse.de ([195.135.220.15]:42836 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751745AbdGZJum (ORCPT ); Wed, 26 Jul 2017 05:50:42 -0400 Date: Wed, 26 Jul 2017 11:50:38 +0200 From: Michal Hocko To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Matthew Wilcox , akpm@linux-foundation.org, ak@linux.intel.com, mtk.manpages@gmail.com, Davidlohr Bueso , khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, aarcange@redhat.com Subject: Re: [RFC PATCH 1/3] mm:hugetlb: Define system call hugetlb size encodings in single file Message-ID: <20170726095038.GD2981@dhcp22.suse.cz> References: <20170328175408.GD7838@bombadil.infradead.org> <1500330481-28476-1-git-send-email-mike.kravetz@oracle.com> <1500330481-28476-2-git-send-email-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1500330481-28476-2-git-send-email-mike.kravetz@oracle.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2516 Lines: 65 On Mon 17-07-17 15:27:59, Mike Kravetz wrote: > If hugetlb pages are requested in mmap or shmget system calls, a huge > page size other than default can be requested. This is accomplished by > encoding the log2 of the huge page size in the upper bits of the flag > argument. asm-generic and arch specific headers all define the same > values for these encodings. > > Put common definitions in a single header file. arch specific code can > still override if desired. > > Signed-off-by: Mike Kravetz with s@HUGETLB_FLAG_ENCODE__16GB@HUGETLB_FLAG_ENCODE_16GB@ Acked-by: Michal Hocko > --- > include/uapi/asm-generic/hugetlb_encode.h | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > create mode 100644 include/uapi/asm-generic/hugetlb_encode.h > > diff --git a/include/uapi/asm-generic/hugetlb_encode.h b/include/uapi/asm-generic/hugetlb_encode.h > new file mode 100644 > index 0000000..aa09fc0 > --- /dev/null > +++ b/include/uapi/asm-generic/hugetlb_encode.h > @@ -0,0 +1,30 @@ > +#ifndef _ASM_GENERIC_HUGETLB_ENCODE_H_ > +#define _ASM_GENERIC_HUGETLB_ENCODE_H_ > + > +/* > + * Several system calls take a flag to request "hugetlb" huge pages. > + * Without further specification, these system calls will use the > + * system's default huge page size. If a system supports multiple > + * huge page sizes, the desired huge page size can be specified in > + * bits [26:31] of the flag arguments. The value in these 6 bits > + * will encode the log2 of the huge page size. > + * > + * The following definitions are associated with this huge page size > + * encoding in flag arguments. System call specific header files > + * that use this encoding should include this file. They can then > + * provide definitions based on these with their own specific prefix. > + * for example #define MAP_HUGE_SHIFT HUGETLB_FLAG_ENCODE_SHIFT. > + */ > + > +#define HUGETLB_FLAG_ENCODE_SHIFT 26 > +#define HUGETLB_FLAG_ENCODE_MASK 0x3f > + > +#define HUGETLB_FLAG_ENCODE_512KB (19 << MAP_HUGE_SHIFT > +#define HUGETLB_FLAG_ENCODE_1MB (20 << MAP_HUGE_SHIFT) > +#define HUGETLB_FLAG_ENCODE_2MB (21 << MAP_HUGE_SHIFT) > +#define HUGETLB_FLAG_ENCODE_8MB (23 << MAP_HUGE_SHIFT) > +#define HUGETLB_FLAG_ENCODE_16MB (24 << MAP_HUGE_SHIFT) > +#define HUGETLB_FLAG_ENCODE_1GB (30 << MAP_HUGE_SHIFT) > +#define HUGETLB_FLAG_ENCODE__16GB (34 << MAP_HUGE_SHIFT) > + > +#endif /* _ASM_GENERIC_HUGETLB_ENCODE_H_ */ > -- > 2.7.5 > -- Michal Hocko SUSE Labs