Re: [PATCH 00/11] Use global pages with PTI

Thomas Gleixner
2018-03-30T20:32:52Z

On Fri, 30 Mar 2018, Dave Hansen wrote:

> On 03/30/2018 05:17 AM, Ingo Molnar wrote:
> > BTW., the expectation on !PCID Intel hardware would be for global pages to help
> > even more than the 0.6% and 1.7% you measured on PCID hardware: PCID already
> > _reduces_ the cost of TLB flushes - so if there's not even PCID then global pages
> > should help even more.
> >
> > In theory at least. Would still be nice to measure it.
>
> I did the lseek test on a modern, non-PCID system:
>
> No Global pages (baseline): 6077741 lseeks/sec
> 94 Global pages (this set): 8433111 lseeks/sec
> +2355370 lseeks/sec (+38.8%)

That's all kernel text, right? What's the result for the case where global
is only set for all user/kernel shared pages?

Thanks,

tglx