On Fri, Oct 26, 2018 at 02:11:48PM -0700, Joel Fernandes wrote:

My thinking is to take it slow and get the patch in in its current state,
since it improves x86. Then as a next step, look into why the arm64 tlb
flushes are that expensive and look into optimizing that. On arm64 I am
testing on a 4.9 kernel so I'm wondering there are any optimizations since
4.9 that can help speed it up there. After that, if all else fails about
speeding up arm64, then I look into developing the cleanest possible solution
where we can keep the lock held for longer and flush lesser.

We rewrote a good chunk of the arm64 TLB invalidation and core mmu_gather
code this merge window, so please do have another look at -rc1!

Will