On Wed, 2018-07-11 at 13:17 -0700, Paul E. McKenney wrote: > As I understand it, they would like to have their guest run uninterrupted > for extended times. Because rcu_virt_note_context_switch() is a > point-in-time quiescent state, it cannot tell RCU about the extended > quiescent state. > > Should we replace the current calls to rcu_virt_note_context_switch() > with rcu_kvm_enter() and rcu_kvm_exit()? Would that be better > than the below architecture-by-architecture approach? Yes it would. I was already starting to mutter about needing the same for ARM and POWER. I'll do a v3 (incorporating your fixes too) in the morning. Thanks. Also... why in $DEITY's name was the existing rcu_virt_note_context_switch() not actually sufficient? If we had that there, why did we need an additional explicit calls to rcu_all_qs() in the KVM loop, or the more complex fixes to need_resched() which ultimately had the same effect, to avoid ten-second latencies?
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