Messages in this thread | | | Date | Mon, 23 Apr 2018 10:51:27 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH tip/core/rcu 01/22] sched: Make non-production PREEMPT cond_resched() help Tasks RCU |
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On Sun, Apr 22, 2018 at 07:32:06PM -0700, Paul E. McKenney wrote: > In CONFIG_PREEMPT=y kernels, cond_resched() is a complete no-op, and > thus cannot help advance Tasks-RCU grace periods. However, such grace > periods are only an issue in non-production benchmarking runs of the > Linux kernel. This commit therefore makes cond_resched() invoke > rcu_note_voluntary_context_switch() for kernels implementing Tasks RCU > even in CONFIG_PREEMPT=y kernels.
I'm confused.. why is having this conditional on TRACEPOINT_BENCHMARK a sane idea?
> > Reported-by: Steven Rostedt <rostedt@goodmis.org> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > --- > include/linux/sched.h | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index b3d697f3b573..fe8f7178a22d 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1617,6 +1617,12 @@ static inline int test_tsk_need_resched(struct task_struct *tsk) > */ > #ifndef CONFIG_PREEMPT > extern int _cond_resched(void); > +#elif defined(CONFIG_TRACEPOINT_BENCHMARK) > +static inline int _cond_resched(void) > +{ > + rcu_note_voluntary_context_switch(current); > + return 0; > +} > #else > static inline int _cond_resched(void) { return 0; } > #endif > -- > 2.5.2 >
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