On Thu, 13 Jan 2005, Nick Piggin wrote:
Note that this was with my ptl removal patches. I can't see why Christoph's
would have _any_ extra overhead as they are, but it looks to me like they're
lacking in atomic ops. So I'd expect something similar for Christoph's when
they're properly atomic.
Pointer operations and word size operations are atomic. So this is mostly
okay.
The issue arises on architectures that have a large pte size than the
wordsize. This is only on i386 PAE mode and S/390. S/390 falls back to
the page table lock for these operations. PAE mode should do the same and
not use atomic ops if they cannot be made to work in a reasonable manner.