linux_dev_学习笔记_内存池实例

2012年3月25日  Sunday

 

1、内核版本号2.6.33.20

 

2、mempool相关函数的简单应用方法

 

3、模块源文件mempool.c

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

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

#define MIN_ELEMENT 4
#define TEST_ELEMENT 4

typedef struct{
    int number;
    char string[128];
}TMemElement;

int elementcount=0;

void *mempool_alloc_test(int gfp_mask,void *pool_data)
{
    TMemElement *data;
    printk("--->mempool_malloc_test\n");

    data=kmalloc(sizeof(TMemElement),gfp_mask);
    if(data!=NULL)data->number=elementcount++;
    return data;
}

void mempool_free_test(void *element,void *pool_data)
{
    printk("--->call mempool_free_test\n");
    if(element!=NULL)kfree(element);
}

int mempool_init(void)
{
    mempool_t *mp;
    TMemElement *element[TEST_ELEMENT];
    int lp;

    printk("Module MEMPOOL Test\n");

    memset(element,0,sizeof(element));

    printk("call mempool_create\n");
    mp=mempool_create(MIN_ELEMENT,
            mempool_alloc_test,
            mempool_free_test,
            NULL);

    printk("call mempool_allocate\n");
    for(lp=0;lp<TEST_ELEMENT;lp++){

        element[lp]=mempool_alloc(mp,GFP_KERNEL);
        if(element[lp]==NULL){
            printk("allocate fail\n");
        }else{
            sprintf(element[lp]->string,
                "allo data %d\n",
                element[lp]->number);
            printk(element[lp]->string);
        }
    }

    printk("mempool free\n");
    for(lp=0;lp<TEST_ELEMENT;lp++){
        if(element[lp]!=NULL)mempool_free(element[lp],mp);
    }

    printk("call mempool_destroy\n");
    mempool_destroy(mp);

    return 0;
}

void mempool_exit(void)
{
    printk("Module MEMPOOL Test End\n");
}

module_init(mempool_init);
module_exit(mempool_exit);
MODULE_LICENSE("Dual BSD/GPL");

4、Makefile

obj-m += mempool.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

~/mempool# make
~/mempool# insmod mempool.ko
~/mempool# dmesg

6、运行结果

[10373.987583] Module MEMPOOL Test
[10373.987609] call mempool_create
[10373.987709] --->mempool_malloc_test
[10373.989115] --->mempool_malloc_test
[10373.989172] --->mempool_malloc_test
[10373.989190] --->mempool_malloc_test
[10373.989229] call mempool_allocate
[10373.989247] --->mempool_malloc_test
[10373.989372] allo data 4
[10373.989385] --->mempool_malloc_test
[10373.989399] allo data 5
[10373.989401] --->mempool_malloc_test
[10373.989405] allo data 6
[10373.989406] --->mempool_malloc_test
[10373.989410] allo data 7
[10373.989423] mempool free
[10373.989447] --->call mempool_free_test
[10373.989477] --->call mempool_free_test
[10373.989480] --->call mempool_free_test
[10373.989481] --->call mempool_free_test
[10373.989493] call mempool_destroy
[10373.989529] --->call mempool_free_test
[10373.989540] --->call mempool_free_test
[10373.989542] --->call mempool_free_test
[10373.989544] --->call mempool_free_test

7、移除模块

~/mempool# rmmod mempool.ko