Chinaunix首页 | 论坛 | 博客
  • 博客访问: 1247241
  • 博文数量: 261
  • 博客积分: 4196
  • 博客等级: 上校
  • 技术积分: 3410
  • 用 户 组: 普通用户
  • 注册时间: 2012-02-17 17:05
文章分类

全部博文(261)

文章存档

2018年(1)

2017年(22)

2016年(2)

2015年(8)

2014年(27)

2013年(40)

2012年(161)

分类: LINUX

2012-06-29 12:39:46

form:

Linux系统的宏HZ的值一般在体系相关的目录下,例如arch/arm/include/asm/param.h下,代码如下:
   
    /* -------------------------------------------------------------------- */
   
    /*
   
    * arch/arm/include/asm/param.h
   
    *
   
    * Copyright (C) 1995-1999 Russell King
   
    *
   
    * This program is free software; you can redistribute it and/or modify
   
    * it under the terms of the GNU General Public License version 2 as
   
    * published by the Free Software Foundation.
   
    */
   
    #ifndef __ASM_PARAM_H
   
    #define __ASM_PARAM_H
   
    #ifdef __KERNEL__
   
    # define HZ CONFIG_HZ /* Internal kernel timer frequency */
   
    # define USER_HZ 100 /* User interfaces are in "ticks" */
   
    # define CLOCKS_PER_SEC (USER_HZ) /* like times() */
   
    #else
   
    # define HZ 100
   
    #endif
   
    #define EXEC_PAGESIZE 4096
   
    #ifndef NOGROUP
   
    #define NOGROUP (-1)
   
    #endif
   
    /* max length of hostname */
   
    #define MAXHOSTNAMELEN 64
   
    #endif
   
    /* -------------------------------------------------------------------- */
   
    一般在make menuconfig下面会有100、250、300、1000的默认配置值,但是其实这些值包含在kernel/timeconst.pl中,这是一个perl脚本:
   
    /* -------------------------------------------------------------------- */
   
    #!/usr/bin/perl
   
    # -----------------------------------------------------------------------
   
    #
   
    # Copyright 2007-2008 rPath, Inc. - All Rights Reserved
   
    #
   
    # This file is part of the Linux kernel, and is made available under
   
    # the terms of the GNU General Public License version 2 or (at your
   
    # option) any later version; incorporated herein by reference.
   
    #
   
    # -----------------------------------------------------------------------
   
    #
   
    #
   
    # Usage: timeconst.pl HZ > timeconst.h
   
    #
   
    # Precomputed values for systems without Math::BigInt
   
    # Generated by:
   
    # timeconst.pl --can 24 32 48 64 100 122 128 200 250 256 300 512 1000 1024 1200
   
    %canned_values = (
   
    24 => [
   
    '0xa6aaaaab','0x2aaaaaa',26,
   
    125,3,
   
    '0xc49ba5e4','0x1fbe76c8b4',37,
   
    3,125,
   
    '0xa2c2aaab','0xaaaa',16,
   
    125000,3,
   
    '0xc9539b89','0x7fffbce4217d',47,
   
    3,125000,
   
    ], 32 => [
   
    '0xfa000000','0x6000000',27,
   
    125,4,
   
    '0x83126e98','0xfdf3b645a',36,
   
    4,125,
   
    '0xf4240000','0x0',17,
   
    31250,1,
   
    '0x8637bd06','0x3fff79c842fa',46,
   
    1,31250,
   
    ], 48 => [
   
    '0xa6aaaaab','0x6aaaaaa',27,
   
    125,6,
   
    '0xc49ba5e4','0xfdf3b645a',36,
   
    6,125,
   
    '0xa2c2aaab','0x15555',17,
   
    62500,3,
   
    '0xc9539b89','0x3fffbce4217d',46,
   
    3,62500,
   
    ], 64 => [
   
    '0xfa000000','0xe000000',28,
   
    125,8,
   
    '0x83126e98','0x7ef9db22d',35,
   
    8,125,
   
    '0xf4240000','0x0',18,
   
    15625,1,
   
    '0x8637bd06','0x1fff79c842fa',45,
   
    1,15625,
   
    ], 100 => [
   
    '0xa0000000','0x0',28,
   
    10,1,
   
    '0xcccccccd','0x733333333',35,
   
    1,10,
   
    '0x9c400000','0x0',18,
   
    10000,1,
   
    '0xd1b71759','0x1fff2e48e8a7',45,
   
    1,10000,
   
    ], 122 => [
   
    '0x8325c53f','0xfbcda3a',28,
   
    500,61,
   
    '0xf9db22d1','0x7fbe76c8b',35,
   
    61,500,
   
    '0x8012e2a0','0x3ef36',18,
   
    500000,61,
   
    '0xffda4053','0x1ffffbce4217',45,
   
    61,500000,
   
    ], 128 => [
   
    '0xfa000000','0x1e000000',29,
   
    125,16,
   
    '0x83126e98','0x3f7ced916',34,
   
    16,125,
   
    '0xf4240000','0x40000',19,
   
    15625,2,
   
    '0x8637bd06','0xfffbce4217d',44,
   
    2,15625,
   
    ], 200 => [
   
    '0xa0000000','0x0',29,
   
    5,1,
   
    '0xcccccccd','0x333333333',34,
   
    1,5,
   
    '0x9c400000','0x0',19,
   
    5000,1,
   
    '0xd1b71759','0xfff2e48e8a7',44,
   
    1,5000,
   
    ], 250 => [
   
    '0x80000000','0x0',29,
   
    4,1,
   
    '0x80000000','0x180000000',33,
   
    1,4,
   
    '0xfa000000','0x0',20,
   
    4000,1,
   
    '0x83126e98','0x7ff7ced9168',43,
   
    1,4000,
   
    ], 256 => [
   
    '0xfa000000','0x3e000000',30,

125,32,
   
    '0x83126e98','0x1fbe76c8b',33,
   
    32,125,
   
    '0xf4240000','0xc0000',20,
   
    15625,4,
   
    '0x8637bd06','0x7ffde7210be',43,
   
    4,15625,
   
    ], 300 => [
   
    '0xd5555556','0x2aaaaaaa',30,
   
    10,3,
   
    '0x9999999a','0x1cccccccc',33,
   
    3,10,
   
    '0xd0555556','0xaaaaa',20,
   
    10000,3,
   
    '0x9d495183','0x7ffcb923a29',43,
   
    3,10000,
   
    ], 512 => [
   
    '0xfa000000','0x7e000000',31,
   
    125,64,
   
    '0x83126e98','0xfdf3b645',32,
   
    64,125,
   
    '0xf4240000','0x1c0000',21,
   
    15625,8,
   
    '0x8637bd06','0x3ffef39085f',42,
   
    8,15625,
   
    ], 1000 => [
   
    '0x80000000','0x0',31,
   
    1,1,
   
    '0x80000000','0x0',31,
   
    1,1,
   
    '0xfa000000','0x0',22,
   
    1000,1,
   
    '0x83126e98','0x1ff7ced9168',41,
   
    1,1000,
   
    ], 1024 => [
   
    '0xfa000000','0xfe000000',32,
   
    125,128,
   
    '0x83126e98','0x7ef9db22',31,
   
    128,125,
   
    '0xf4240000','0x3c0000',22,
   
    15625,16,
   
    '0x8637bd06','0x1fff79c842f',41,
   
    16,15625,
   
    ], 1200 => [
   
    '0xd5555556','0xd5555555',32,
   
    5,6,
   
    '0x9999999a','0x66666666',31,
   
    6,5,
   
    '0xd0555556','0x2aaaaa',22,
   
    2500,3,
   
    '0x9d495183','0x1ffcb923a29',41,
   
    3,2500,
   
    ]
   
    );
   
    /* -------------------------------------------------------------------- */
   
    上面红色部分简绍了使用方法,有的时候,修改了HZ的值,可能要手动运行一下,例如,修改HZ=512,则可以在kernel目录下: timeconst.pl 512 > timeconst.h
   
    也就是说kernel目录下的timeconst.h是动态生成的
   
    /* -------------------------------------------------------------------- */
   
    /* Automatically generated by kernel/timeconst.pl */
   
    /* Conversion constants for HZ == 512 */
   
    #ifndef KERNEL_TIMECONST_H
   
    #define KERNEL_TIMECONST_H
   
    #include <linux/param.h>
   
    #include <linux/types.h>
   
    #if HZ != 512
   
    #error "kernel/timeconst.h has the wrong HZ value!"
   
    #endif
   
    #define HZ_TO_MSEC_MUL32 U64_C(0xfa000000)
   
    #define HZ_TO_MSEC_ADJ32 U64_C(0x7e000000)
   
    #define HZ_TO_MSEC_SHR32 31
   
    #define HZ_TO_MSEC_NUM U64_C(125)
   
    #define HZ_TO_MSEC_DEN U64_C(64)
   
    #define MSEC_TO_HZ_MUL32 U64_C(0x83126e98)
   
    #define MSEC_TO_HZ_ADJ32 U64_C(0xfdf3b645)
   
    #define MSEC_TO_HZ_SHR32 32
   
    #define MSEC_TO_HZ_NUM U64_C(64)
   
    #define MSEC_TO_HZ_DEN U64_C(125)
   
    #define HZ_TO_USEC_MUL32 U64_C(0xf4240000)
   
    #define HZ_TO_USEC_ADJ32 U64_C(0x1c0000)
   
    #define HZ_TO_USEC_SHR32 21
   
    #define HZ_TO_USEC_NUM U64_C(15625)
   
    #define HZ_TO_USEC_DEN U64_C(8)
   
    #define USEC_TO_HZ_MUL32 U64_C(0x8637bd06)
   
    #define USEC_TO_HZ_ADJ32 U64_C(0x3ffef39085f)
   
    #define USEC_TO_HZ_SHR32 42
   
    #define USEC_TO_HZ_NUM U64_C(8)
   
    #define USEC_TO_HZ_DEN U64_C(15625)
   
    #endif /* KERNEL_TIMECONST_H */
   
    /* -------------------------------------------------------------------- */
   
    因此,下次如果修改了HZ的值,而这个值是perl脚本支持的,但却报类似的错:
   
    In file included from kernel/time.c:45:
   
    kernel/timeconst.h:11:2: error: #error "kernel/timeconst.h has the wrong HZ value!"
   
    make[1]: *** [kernel/time.o] Error 1
   
    make: *** [kernel] Error 2
   
    make: *** Waiting for unfinished jobs…
   
    那就要手动执行以下这个perl脚本了。而对于这个HZ值与您的系统的性能关系,还需要仔细斟酌,我目前的项目也遇到了类似的问题,可能有关,继续研究。

出现问题时:在kernel目录下: ./timeconst.pl XX > timeconst.h来改变HZ的值,而这个值可能是:24 32 48 64 100 122 128 200 250 256 300 512 1000 1024 1200。一个个试,尝试到能成功编译为止。在kernel下 timeconst.h。是生成的,每次不同!

阅读(4425) | 评论(0) | 转发(1) |
给主人留下些什么吧!~~