On Fri, 08 Dec 2017 16:41:38 +0800 "Huang\, Ying" <ying.hu...@intel.com> wrote:
> > Why do we need srcu here? Is it enough with rcu like below? > > > > It might have a bug/room to be optimized about performance/naming. > > I just wanted to show my intention. > > Yes. rcu should work too. But if we use rcu, it may need to be called > several times to make sure the swap device under us doesn't go away, for > example, when checking si->max in __swp_swapcount() and > add_swap_count_continuation(). And I found we need rcu to protect swap > cache radix tree array too. So I think it may be better to use one > calling to srcu_read_lock/unlock() instead of multiple callings to > rcu_read_lock/unlock(). Or use stop_machine() ;) It's very crude but it sure is simple. Does anyone have a swapoff-intensive workload?
