From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 5 Dec 2006 22:09:06 +0900 From: KAMEZAWA Hiroyuki Subject: [RFC][PATCH] vmemmap on sparsemem v2 [4/5] optimized pfn_valid Message-Id: <20061205220906.f1d24dfc.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20061205214517.5ad924f6.kamezawa.hiroyu@jp.fujitsu.com> References: <20061205214517.5ad924f6.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: linux-mm@kvack.org, clameter@engr.sgi.com, apw@shadowen.org List-ID: This implements pfn_valid() as ia64's vmem_map does. This eliminates access to mem_section[] array by usual ops. Because vmemmap on sparsemem is aligned. access check function can be easier than ia64's. Signed-Off-By: KAMEZAWA Hiruyoki include/linux/mmzone.h | 14 ++++++++++++++ mm/sparse.c | 23 +++++++++++++++++++++++ 2 files changed, 37 insertions(+) Index: devel-2.6.19-rc6-mm2/include/linux/mmzone.h =================================================================== --- devel-2.6.19-rc6-mm2.orig/include/linux/mmzone.h 2006-12-05 21:25:43.000000000 +0900 +++ devel-2.6.19-rc6-mm2/include/linux/mmzone.h 2006-12-05 21:45:21.000000000 +0900 @@ -752,12 +752,27 @@ return __nr_to_section(pfn_to_section_nr(pfn)); } +#if defined(SPARSEMEM_VMEM_MAP) && defined(CONFIG_USE_OPT_PFN_VALID) +/* + * Uses hardware assist instead of mem_section[] table walking. + * good for SPARSEMEM_EXTREME + * To use this, you may need arch support in page fault handler. + */ +static inline int pfn_valid(unsigned long pfn) +{ + struct page *pg = pfn_to_page(pfn); + return (VIRTUAL_MEM_MAP <= pg && + pg < (VIRUTAL_MEM_MAP + VIRTUAL_MEM_MAP_SIZE) && + check_valid_memmap(pg)); +} +#else static inline int pfn_valid(unsigned long pfn) { if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) return 0; return valid_section(__nr_to_section(pfn_to_section_nr(pfn))); } +#endif /* * These are _only_ used during initialisation, therefore they Index: devel-2.6.19-rc6-mm2/mm/sparse.c =================================================================== --- devel-2.6.19-rc6-mm2.orig/mm/sparse.c 2006-12-05 21:25:43.000000000 +0900 +++ devel-2.6.19-rc6-mm2/mm/sparse.c 2006-12-05 21:47:21.000000000 +0900 @@ -103,6 +103,22 @@ #ifdef CONFIG_SPARSEMEM_VMEMMAP +#ifdef CONFIG_USE_OPT_PFN_VALID + +/* check mem_map is valid or not by accessing it. + Because virtual mem_map/sparse mem is always alined, just __get_user() + check is necessary. + */ +int check_valid_memmap(struct page *pg) +{ + char byte; + if (__get_user(byte, (char __user*)pg) == 0) + return 1; + return 0; +} + +EXPORT_SYMBOL(check_valid_memmap); +#endif static void* __meminit pte_alloc_vmem_map(int node) { -- 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