延长filemap_sync函数的执行时间

willcream

在msync系统调用里，会调用到filemap_sync。
filemap_sync scans the Page Table entries corresponding to the linear address intervals included in the memory region. For each page found, it invokes flush_tlb_page( ) to flush the corresponding translation lookaside buffers, and marks the page as dirty.

1. int filemap_sync(struct vm_area_struct * vma, unsigned long address,
   
2.         size_t size, unsigned int flags)
   
3. {
   
4.         pgd_t * dir;
   
5.         unsigned long end = address + size;
   
6.         int error = 0;
   
7. 
   
8. 
   
9.         spin_lock(&vma->vm_mm->page_table_lock);
   
10. 
    
11.         dir = pgd_offset(vma->vm_mm, address);
    
12.         flush_cache_range(vma->vm_mm, end - size, end);
    
13.         if (address >= end)
    
14.                 BUG();
    
15.         do {
    
16.                 error |= filemap_sync_pmd_range(dir, address, end - address, vma, flags);
    
17.                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
    
18.                 dir++;
    
19.         } while (address && (address < end));
    
20.         flush_tlb_range(vma->vm_mm, end - size, end);
    
21. 
    
22.         spin_unlock(&vma->vm_mm->page_table_lock);
    
23. 
    
24.         return error;
    
25. }

复制代码

我现在想在用户空间代码中实现让这个filemap_sync函数执行得越久越好，请问有什么方法吗？