Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031101AbbDWW0W (ORCPT ); Thu, 23 Apr 2015 18:26:22 -0400 Received: from mga03.intel.com ([134.134.136.65]:48787 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030837AbbDWW0V convert rfc822-to-8bit (ORCPT ); Thu, 23 Apr 2015 18:26:21 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,634,1422950400"; d="scan'208";a="484885905" From: "Luck, Tony" To: Andrew Morton , Zhang Zhen CC: Linux MM , Linux Kernel Mailing List , "linux@arm.linux.org.uk" , "catalin.marinas@arm.com" , "james.hogan@imgtec.com" , "ralf@linux-mips.org" , "benh@kernel.crashing.org" , "schwidefsky@de.ibm.com" , "cmetcalf@ezchip.com" , "David Rientjes" , "James.Yang@freescale.com" , "aneesh.kumar@linux.vnet.ibm.com" Subject: RE: [PATCH] mm/hugetlb: reduce arch dependent code about huge_pmd_unshare Thread-Topic: [PATCH] mm/hugetlb: reduce arch dependent code about huge_pmd_unshare Thread-Index: AQHQdoW5aVsrUdm0hEu/x0E6Wa7NH51brSUA//+NrHA= Date: Thu, 23 Apr 2015 22:26:18 +0000 Message-ID: <3908561D78D1C84285E8C5FCA982C28F32A6478B@ORSMSX114.amr.corp.intel.com> References: <1428996566-86763-1-git-send-email-zhenzhang.zhang@huawei.com> <552CC328.9050402@huawei.com> <20150423151118.40c41fb1810f2aaa877163ae@linux-foundation.org> In-Reply-To: <20150423151118.40c41fb1810f2aaa877163ae@linux-foundation.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.22.254.138] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 705 Lines: 17 > Memory fails me. Why do some architectures (arm, arm64, x86_64) want > huge_pmd_[un]share() while other architectures (ia64, tile, mips, > powerpc, metag, sh, s390) do not? Potentially laziness/ignorance-of-feature? It looks like this feature started on x86_64 and then spread to arm*. Huge pages are weird on ia64 in that they have to be in a specific range of virtual addresses (region 4). But I don't see why that would prevent sharing pmd's. -Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/