Messages in this thread | | | Date | Wed, 1 Jul 2015 06:41:44 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH RFC tip/core/rcu 2/5] rcu: Short-circuit normal GPs via expedited GPs |
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On Wed, Jul 01, 2015 at 12:05:21PM +0200, Peter Zijlstra wrote: > On Tue, Jun 30, 2015 at 02:48:27PM -0700, Paul E. McKenney wrote: > > rsp->gp_state = RCU_GP_WAIT_FQS; > > ret = wait_event_interruptible_timeout(rsp->gp_wq, > > + ((gf = READ_ONCE(rsp->gp_flags)) & > > + RCU_GP_FLAG_FQS) || > > + (!READ_ONCE(rnp->qsmask) && > > + !rcu_preempt_blocked_readers_cgp(rnp)) || > > + rcu_exp_gp_seq_done(rsp->exp_rsp, > > + rsp->gp_exp_snap), > > + j); > > rsp->gp_state = RCU_GP_DONE_FQS; > > How can the GP be done if we timed out or got interrupted?
If all the CPUs still blocking the grace period went idle, or in a NO_HZ_FULL kernel, entered nohz_full userspace execution. Or, if certain low-probability races happen, went offline.
Thanx, Paul
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