Messages in this thread | | | Date | Thu, 5 May 2011 22:46:57 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH tip/core/rcu 05/86] rcu: move TREE_RCU from softirq to kthread |
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On Thu, May 05, 2011 at 05:31:35PM +0800, Yong Zhang wrote: > On Sun, May 1, 2011 at 9:20 PM, Paul E. McKenney > <paulmck@linux.vnet.ibm.com> wrote: > > From: Paul E. McKenney <paul.mckenney@linaro.org> > > > > If RCU priority boosting is to be meaningful, callback invocation must > > be boosted in addition to preempted RCU readers. Otherwise, in presence > > of CPU real-time threads, the grace period ends, but the callbacks don't > > get invoked. If the callbacks don't get invoked, the associated memory > > doesn't get freed, so the system is still subject to OOM. > > > > But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit > > moves the callback invocations to a kthread, which can be boosted easily. > > > > Also add comments and properly synchronized all accesses to > > rcu_cpu_kthread_task, as suggested by Lai Jiangshan. > > > > Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > --- > [snip] > > + * Drop to non-real-time priority and yield, but only after posting a > > + * timer that will cause us to regain our real-time priority if we > > + * remain preempted. Either way, we restore our real-time priority > > + * before returning. > > + */ > > +static void rcu_yield(int cpu) > > +{ > > + struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu); > > + struct sched_param sp; > > + struct timer_list yield_timer; > > + > > + setup_timer(&yield_timer, rcu_cpu_kthread_timer, (unsigned long)rdp); > > setup_timer_on_stack() should be used here :)
Good eyes!!! Fixed, will update the -rcu git tree.
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