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SubjectRe: [PATCH 0/3] Use global pages with PTI
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On 02/15/2018 09:47 AM, Linus Torvalds wrote:
> On Thu, Feb 15, 2018 at 5:20 AM, Dave Hansen
> <dave.hansen@linux.intel.com> wrote:
>> During the switch over to PTI, we seem to have lost our ability to have
>> GLOBAL mappings.
...
> 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..

Same test as last time except I'm using all 4 cores on a Skylake desktop
instead of just 1. The test is this:

> https://github.com/antonblanchard/will-it-scale/blob/master/tests/lseek1.c

With PCIDs, lseek()s/second go up around 2% to 3% with the these patches
enabling the global bit (it's noisy). I measured it at 3% before, so
definitely the same ballpark. That was also before all of Andy's
trampoline stuff and the syscall fast path removal.

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