On Wed, Apr 19, 2017 at 06:02:45AM -0700, Paul E. McKenney wrote: > On Wed, Apr 19, 2017 at 01:28:45PM +0200, Peter Zijlstra wrote: > > > > So the thing Maz complained about is because KVM assumes > > synchronize_srcu() is 'free' when there is no srcu_read_lock() activity. > > This series 'breaks' that. > > > > I've not looked hard enough at the new SRCU to see if its possible to > > re-instate that feature. > > And with the fix I gave Maz, the parallelized version is near enough > to being free as well. It was just a stupid bug on my part: I forgot > to check for expedited when scheduling callbacks.
Right, although for the old SRCU it was true for !expedited as well. Just turns out the KVM memslots crud already uses synchronize_srcu_expedited(). <rant>without a friggin' comment; hate @expedited</rant>
