linux_dev_学习笔记_动态内存实例

2012年3月25日  Sunday

 

1、内核版本号2.6.33.20

 

2、kmalloc() kfree() vmalloc() vfree() __get_free_pages()的应用方法举例

 

3、模块源文件basicmem.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>

#include <linux/slab.h>
#include <linux/vmalloc.h>

void kmalloc_test(void)
{
    char *buff;

    printk("kmalloc test\n");

    buff = kmalloc (1024,GFP_KERNEL);

    if(buff != NULL){
        sprintf(buff,"test memory\n");
        printk(buff);

        kfree(buff);
    }
    buff =kmalloc(32*PAGE_SIZE,GFP_KERNEL);
    if(buff !=NULL){
        printk("big memory ok\n");
        kfree(buff);
    }

}

void vmalloc_test(void)
{
    char *buff;
    printk("vmalloc test\n");

    buff=vmalloc(33*PAGE_SIZE);
    if(buff!=NULL){
        sprintf(buff,"vmalloc test ok\n");
        printk(buff);

        vfree(buff);
    }
}

void get_free_pages_test(void)
{
    char* buff;
    int order;

    printk("get_free_pages test\n");

    order=get_order(8192*10);
    buff=__get_free_pages(GFP_KERNEL,order);
    if(buff!=NULL){
        sprintf(buff,"__get_free_pages test ok[%d]\n",order);
        printk(buff);
        free_pages(buff,order);
    }
}

int memtest_init(void)
{

    printk ("module memory test\n");

    kmalloc_test();
    vmalloc_test();
    get_free_pages_test();
    return 0;

}

void memtest_exit(void)
{
    printk("module memory test end\n");
}

module_init(memtest_init);
module_exit(memtest_exit);

MODULE_LICENSE("Dual BSD_GPL");

 

4、Makefile

obj-m = basicmem.o

CURRENT_PATH := $(shell pwd)

LINUX_KERNEL := $(shell uname -r)

LINUX_KERNEL_PATH := /usr/src/linux-$(LINUX_KERNEL)

all:
    make -C $(LINUX_KERNEL_PATH) M=$(CURRENT_PATH) modules
clean:
    #make -C $(LINUX_KERNEL_PAHT) M=$(CURRENT_PATH) clean
    rm *.mod.*
    rm *.order
    rm *.o
    rm *.symvers

5、运行方法

~/malloc# make
~/malloc# insmod memtest.ko
~/malloc# dmesg

6、运行结果

[ 8913.072139] module memory test
[ 8913.072162] kmalloc test
[ 8913.072240] test memory
[ 8913.072288] big memory ok
[ 8913.072320] vmalloc test
[ 8913.072416] vmalloc test ok
[ 8913.072480] get_free_pages test
[ 8913.072515] __get_free_pages test ok[5]

7、移除模块

 

~/mempool# rmmod memtest.ko