From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 6A4916B005A for ; Fri, 14 Aug 2009 10:09:12 -0400 (EDT) Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e39.co.us.ibm.com (8.14.3/8.13.1) with ESMTP id n7EE4CgB022918 for ; Fri, 14 Aug 2009 08:04:12 -0600 Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id n7EE8wq5092774 for ; Fri, 14 Aug 2009 08:08:58 -0600 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n7EE8vHs001736 for ; Fri, 14 Aug 2009 08:08:57 -0600 From: Eric B Munson Subject: [PATCH 3/3] Add MAP_HUGETLB example V3 Date: Fri, 14 Aug 2009 15:08:49 +0100 Message-Id: In-Reply-To: References: In-Reply-To: References: Sender: owner-linux-mm@kvack.org To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: linux-man@vger.kernel.org, akpm@linux-foundation.org, mtk.manpages@gmail.com, Eric B Munson List-ID: This patch adds an example of how to use the MAP_HUGETLB flag to the vm documentation directory and a reference to the example in hugetlbpage.txt. Signed-off-by: Eric B Munson --- Changes from V2: Rebase to newest linux-2.6 tree Fix comment in example referencing MAP_LARGEPAGE Move example code to its own file Update hugetlbpage.txt with MAP_HUGETLB information and example reference Add map_hugetlb.c to 00-INDEX Changes from V1: Rebase to newest linux-2.6 tree Change MAP_LARGEPAGE to MAP_HUGETLB to match flag name in huge page shm Documentation/vm/00-INDEX | 2 + Documentation/vm/hugetlbpage.txt | 14 ++++--- Documentation/vm/map_hugetlb.c | 77 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 87 insertions(+), 6 deletions(-) create mode 100644 Documentation/vm/map_hugetlb.c diff --git a/Documentation/vm/00-INDEX b/Documentation/vm/00-INDEX index 2f77ced..aabd973 100644 --- a/Documentation/vm/00-INDEX +++ b/Documentation/vm/00-INDEX @@ -20,3 +20,5 @@ slabinfo.c - source code for a tool to get reports about slabs. slub.txt - a short users guide for SLUB. +map_hugetlb.c + - an example program that uses the MAP_HUGETLB mmap flag. diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt index ea8714f..6a8feab 100644 --- a/Documentation/vm/hugetlbpage.txt +++ b/Documentation/vm/hugetlbpage.txt @@ -146,12 +146,14 @@ Regular chown, chgrp, and chmod commands (with right permissions) could be used to change the file attributes on hugetlbfs. Also, it is important to note that no such mount command is required if the -applications are going to use only shmat/shmget system calls. Users who -wish to use hugetlb page via shared memory segment should be a member of -a supplementary group and system admin needs to configure that gid into -/proc/sys/vm/hugetlb_shm_group. It is possible for same or different -applications to use any combination of mmaps and shm* calls, though the -mount of filesystem will be required for using mmap calls. +applications are going to use only shmat/shmget system calls or mmap with +MAP_HUGETLB. Users who wish to use hugetlb page via shared memory segment +should be a member of a supplementary group and system admin needs to +configure that gid into /proc/sys/vm/hugetlb_shm_group. It is possible for +same or different applications to use any combination of mmaps and shm* +calls, though the mount of filesystem will be required for using mmap calls +without MAP_HUGETLB. For an example of how to use mmap with MAP_HUGETLB see +map_hugetlb.c. ******************************************************************* diff --git a/Documentation/vm/map_hugetlb.c b/Documentation/vm/map_hugetlb.c new file mode 100644 index 0000000..e2bdae3 --- /dev/null +++ b/Documentation/vm/map_hugetlb.c @@ -0,0 +1,77 @@ +/* + * Example of using hugepage memory in a user application using the mmap + * system call with MAP_HUGETLB flag. Before running this program make + * sure the administrator has allocated enough default sized huge pages + * to cover the 256 MB allocation. + * + * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. + * That means the addresses starting with 0x800000... will need to be + * specified. Specifying a fixed address is not required on ppc64, i386 + * or x86_64. + */ +#include +#include +#include +#include +#include + +#define LENGTH (256UL*1024*1024) +#define PROTECTION (PROT_READ | PROT_WRITE) + +#ifndef MAP_HUGETLB +#define MAP_HUGETLB 0x40 +#endif + +/* Only ia64 requires this */ +#ifdef __ia64__ +#define ADDR (void *)(0x8000000000000000UL) +#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED) +#else +#define ADDR (void *)(0x0UL) +#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) +#endif + +void check_bytes(char *addr) +{ + printf("First hex is %x\n", *((unsigned int *)addr)); +} + +void write_bytes(char *addr) +{ + unsigned long i; + + for (i = 0; i < LENGTH; i++) + *(addr + i) = (char)i; +} + +void read_bytes(char *addr) +{ + unsigned long i; + + check_bytes(addr); + for (i = 0; i < LENGTH; i++) + if (*(addr + i) != (char)i) { + printf("Mismatch at %lu\n", i); + break; + } +} + +int main(void) +{ + void *addr; + + addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, 0, 0); + if (addr == MAP_FAILED) { + perror("mmap"); + exit(1); + } + + printf("Returned address is %p\n", addr); + check_bytes(addr); + write_bytes(addr); + read_bytes(addr); + + munmap(addr, LENGTH); + + return 0; +} -- 1.6.3.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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