[PATCH 4/7] powerpc: Free up four 64K PTE bits in 64K backed HPTE pages

[Aneesh Kumar K.V]

On 10/24/2017 12:52 AM, Ram Pai wrote:
> On Thu, Sep 14, 2017 at 06:13:57PM +1000, Benjamin Herrenschmidt wrote:
>> On Fri, 2017-09-08 at 15:44 -0700, Ram Pai wrote:
>>> The second part of the PTE will hold
>>> (H_PAGE_F_SECOND|H_PAGE_F_GIX) at bit 60,61,62,63.
>>> NOTE: None of the bits in the secondary PTE were not used
>>> by 64k-HPTE backed PTE.
>>
>> Have you measured the performance impact of this ? The second part of
>> the PTE being in a different cache line there could be one...
> 
> hmm..missed responding to this comment.
> 
> I did a preliminay measurement running mmap bench in the selftest.
> Ran it multiple times. almost always the numbers were either equal-to
> or better-than without the patch-series.

mmap bench doesn't do any fault. It is just mmap/munmap in loop.

-aneesh