share memory

[zhonglei]

hi:
  I want my driver to transfer 512byte data from kernel to user-space every 100us in the interrupt routine. Because the amount of data is  large, the copy_to_user(...) is too slow to fit the request.I tried to use sys_shmat in my driver to build a share memory,but the return of the function is a kernel virtual address which I can not use in the kernel interrupt routine directory! 
  What can I do? What function can I use to convert the kernel virtual address to kernel logic address? Or is there some other good way to handle this problem?
  Thanks a lot!
zhonglei