On Fri, Jul 08, 2016 at 04:49:01PM +0100, Will Deacon wrote:

On Fri, Jul 08, 2016 at 11:43:50AM -0400, Chris Metcalf wrote:

quoted

I am hopeful that this patch [1] can be picked up for the 4.8 merge window
in the arm64 tree.  As I mentioned in my last patch series that included
this patch [2], I'm hopeful that this version addresses the performance
issues that were seen with Mark's original patch.  This version tests the
TIF flags prior to calling out to the loop in C code.

I still need to get round to measuring that again. This might also
conflict with a late fix I just sent for 4.7.

FWIW, I've failed to measure any performance overhead from this change,
so it certainly looks better thsn Mark's original patch from that angle.

Will