Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933952AbcLIQkO (ORCPT ); Fri, 9 Dec 2016 11:40:14 -0500 Received: from mga04.intel.com ([192.55.52.120]:46543 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933294AbcLIQkM (ORCPT ); Fri, 9 Dec 2016 11:40:12 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,324,1477983600"; d="scan'208";a="38589539" Date: Fri, 9 Dec 2016 08:40:11 -0800 From: Andi Kleen To: "Kirill A. Shutemov" Cc: Ingo Molnar , "Kirill A. Shutemov" , Linus Torvalds , Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , Arnd Bergmann , "H. Peter Anvin" , Dave Hansen , Andy Lutomirski , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC, PATCHv1 00/28] 5-level paging Message-ID: <20161209164011.GL8388@tassilo.jf.intel.com> References: <20161208162150.148763-1-kirill.shutemov@linux.intel.com> <20161209050130.GC2595@gmail.com> <20161209103722.GE30380@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161209103722.GE30380@node.shutemov.name> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 544 Lines: 13 > On other hand, large virtual address space would put more pressure on > cache -- at least one more page table per process, if we make 56-bit VA > default. The top level page always has to be there unless you disable it at boot time (unless you go for a scheme where some processes share top level pages, and others do not, which would likely be very complicated) But even with that it is more than one: A typical set up has at least two extra 4K pages overhead, one for the bottom and one for the top mappings. Could easily be more. -Andi