Re: [PATCH 0/3] Use global pages with PTI

[Linus Torvalds]

On Thu, Feb 15, 2018 at 5:20 AM, Dave Hansen
<dave.hansen@xxxxxxxxxxxxxxx> 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