On Tue, Feb 01, 2005 at 03:14:47PM -0800, Matthew Dillon wrote:
> :This is an optimisation for the intra-program switch if you want to call it so.
> :I would argue that the normal switch case is either user -> kernel or to
> :a different kernel thread.
>
> You pretty much always want to have just a single page table with a
> threaded program. The %cr3 optimization is a nice plus, but it isn't
> why the page table is being shared. The page table is being shared
> because trying to build a threaded program WITHOUT sharing the page
> table is extremely expensive. Every time you'd allocate memory or map
> something it would have to be replicated across N page tables.
> Performance would be destroyed.
But you can still share most parts of the page table, if you exploit
the two level approach.
Joerg
>
> -Matt