Re: copy_from_user_page/copy_to_user_page fix

[Ralf Baechle <ralf@linux-mips.org>]

On Wed, Feb 09, 2005 at 10:52:56PM +0900, Atsushi Nemoto wrote:

> ralf> I'm going to apply this because it's a correct fix; the
> ralf> temporary mapping strategy as we've discussed for the dup_mmap
> ralf> problem would be preferable.
> 
> Thank you.  I agree that the temporary mapping will be more efficient
> though I chose a simple fix.  I suppose a performance requirement for
> ptrace() would be less than the dup_mmap (fork()).

People have come up with creative abuses for ptrace which actually make
it a performance critical path.  Especially UML should be mentioned in
this cathegory.  And we're talkign about a few thousand cycles differences
per ptrace invocation.

  Ralf