From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 19 Oct 2006 18:45:18 -0700 (PDT) From: Christoph Lameter Subject: Re: [RFC] virtual memmap for sparsemem [2/2] for ia64. In-Reply-To: <20061020103534.35a92813.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20061019172328.4bcb1551.kamezawa.hiroyu@jp.fujitsu.com> <20061020103534.35a92813.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: linux-ia64@vger.kernel.org, linux-mm@kvack.org List-ID: On Fri, 20 Oct 2006, KAMEZAWA Hiroyuki wrote: > Maximun phyisical address size of Itanium2 looks 50bits. Then, we need > sizeof (struct page) * (50 - PAGE_SHIFT) size of virtual address space. Right. That is 4TB which can be a portion of the 128TB VMALLOC space. Have you seen my patchset that does the calculation on linux-ia674? > > #ifdef CONFIG_PGTABLE_4 > #define PGDIR_SHIFT (PUD_SHIFT + (PTRS_PER_PTD_SHIFT)) > #else > #define PGDIR_SHIFT (PMD_SHIFT + (PTRS_PER_PTD_SHIFT)) > #endif > > Then, considering PAGE_SHIFT=14 case, > 4-level-page-table mapsize:(1 << (4 * PAGE_SHIFT - 9) -> (1 << 47) > 3-level-page-table mapsize:(1 << (3 * PAGE_SHIFT - 6) -> (1 << 36) You are missing one PAGE_SHIFT (the page that is referred to !) 3 level is 47. 4 level is 58. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org