On Thu, Feb 15, 2018 at 5:20 AM, Dave Hansen <dave.han...@linux.intel.com> wrote: > > During the switch over to PTI, we seem to have lost our ability to have > GLOBAL mappings.
Oops. Odd, I have this distinct memory of somebody even _testing_ the global bit performance when I pointed out that we shouldn't just make the bit go away entirely. [ goes back and looks at archives ] Oh, that was in fact you who did that performance test. Heh. Anyway, back then you claimed a noticeable improvement on that will-it-scale test (although a bigger one when pcid wasn't available), so yes, if we lost the "global pages for the shared user/kernel mapping" bit we should definitely get this fixed. Did you perhaps re-run any benchmark numbers just to verify? Because it's always good to back up patches that should improve performance with actual numbers.. Linus