Re: [PATCH 00/12] Avoid synchronous TLB invalidation for intermediate page-table entries on arm64

From: Peter Zijlstra
Date: Fri Aug 31 2018 - 06:54:23 EST

On Fri, Aug 31, 2018 at 08:32:34PM +1000, Nicholas Piggin wrote:
> Oh gee, I suppose. powerpc hash is kind of interesting because it's
> crazy, Aneesh knows that code a lot better than I do. radix modulo
> some minor details of exact instructions is fairly like x86

The whole TLB broadcast vs explicit IPIs is a fairly big difference in
my book.

Anyway, have you guys tried the explicit IPI approach? Depending on how
IPIs are routed vs broadcasts it might save a little bus traffic. No
point in getting all CPUs to process the TLBI when there's only a hand
full that really need it.

OTOH, I suppose the broadcast thing has been optimized to death on the
hardware side, so who knows..