[RFC PATCH 0/7] powerpc/64s/radix TLB flush performance improvements

[Anshuman Khandual]

On 10/31/2017 12:14 PM, Nicholas Piggin wrote:
> Here's a random mix of performance improvements for radix TLB flushing
> code. The main aims are to reduce the amount of translation that gets
> invalidated, and to reduce global flushes where we can do local.
> 
> To that end, a parallel kernel compile benchmark using powerpc:tlbie
> tracepoint shows a reduction in tlbie instructions from about 290,000
> to 80,000, and a reduction in tlbiel instructions from 49,500,000 to
> 15,000,000. Looks great, but unfortunately does not translate to a
> statistically significant performance improvement! The needle on TLB
> misses does not move much, I suspect because a lot of the flushing is
> done a startup and shutdown, and because a significant cost of TLB
> flushing itself is in the barriers.

Does memory barrier initiate a single global invalidation with tlbie ?