On Wed, Mar 29, 2023 at 11:35:36PM +0200, Frederic Weisbecker wrote: > On Wed, Mar 29, 2023 at 01:58:06PM -0700, Paul E. McKenney wrote: > > On Wed, Mar 29, 2023 at 06:02:03PM +0200, Frederic Weisbecker wrote: > > > Callbacks can only be queued as lazy on NOCB CPUs, therefore iterating > > > over the NOCB mask is enough for both counting and scanning. Just lock > > > the mostly uncontended barrier mutex on counting as well in order to > > > keep rcu_nocb_mask stable. > > > > > > Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx> > > > > Looks plausible. ;-) > > > > What are you doing to test this? For that matter, what should rcutorture > > be doing to test this? My guess is that the current callback flooding in > > rcu_torture_fwd_prog_cr() should do the trick, but figured I should ask. > > All I did was to trigger these shrinker callbacks through debugfs > (https://docs.kernel.org/admin-guide/mm/shrinker_debugfs.html) > > But rcutorture isn't testing it because: > > - No torture config has CONFIG_RCU_LAZY > - rcutorture doesn't do any lazy call_rcu() (always calls hurry for the > main RCU flavour). > > And I suspect rcutorture isn't ready for accepting the lazy delay, that would > require some special treatment. All fair points! And yes, any non-lazy callback would delazify everything, so as it is currently constituted, it would not be testing very much of the lazy-callback state space. Thanx, Paul
