遇到一个需求，需要在内核中统计mysql进程匿名页的访问热度。

配置系统环境

将透明大页关闭:
echo never > /sys/kernel/mm/transparent_hugepage/enabled

寻找mysql的task_struct

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struct task_struct *task = NULL;

//0:not found 1:found
int findMysql(void)
{
    int ret = 0;
    struct task_struct *proc;
    for_each_process(proc){
        if(!strcmp(proc->comm, "mysqld")){
            task = proc;
            ret = 1;
            break;
        }
    }
    return ret;
}

统计匿名页热度

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int tem;
struct page *page = NULL;
struct page_cgroup *pc;
struct vm_area_struct *vma;
unsigned long addr = 0;

for(vma = task->mm->mmap; vma != NULL; vma = vma->vm_next){
    for(addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE){
        page = follow_page(vma, addr, 0);
        if (page && PageAnon(page)){
            pc = lookup_page_cgroup(page);
            tem = page_referenced(page, 0, pc, &vm_flags) ? 1 : 0;
            sprintf(str_buf, "22222222:%ul:%d\n", page_to_pfn(page), tem);
            write_to_file((void *)str_buf, strlen(str_buf));
        }
    }
}