Re: rcutorture: meaning of "End of test: RCU_HOTPLUG"

["Paul E. McKenney" <paulmck@linux.ibm.com>]

On Tue, Jan 22, 2019 at 11:40:53AM +0800, Su Yue wrote:
> Hi, guys
>   While running rcutorture tests with "onoff_interval", some tests
> failed and results show like:
> 
> =====================================================================
> [  316.354501] srcud-torture:--- End of test: RCU_HOTPLUG:
> nreaders=1 nfakewriters=4 stat_interval=60 verbose=2
> test_no_idle_hz=1 shuffle_interval=3 stutter=5 irqreader=1 fq\
> s_duration=0 fqs_holdoff=0 fqs_stutter=3 test_boost=1/0
> test_boost_interval=7 test_boost_duration=4 shutdown_secs=0
> stall_cpu=0 stall_cpu_holdoff=10 stall_cpu_irqsoff=0 n_ba\
> rrier_cbs=0 onoff_interval=3 onoff_holdoff=0
> ====================================================================
> 
> I am wondering that meaning of "RCU_HOTPLUG". Is it expected because
> cpu hotplug is enabled in the test? Or just represents another type of
> failure?

This says that at least one CPU hotplug operation failed, that is,
the CPU didn't actually come online or go offline as requested.  If you
are introducing CPU hotplug to an architecture, this usually indicates
that you have bugs in your CPU-hotplug code.  Or it nmight be that
RCU grace periods failed to progress -- though this would normally
also result in RCU CPU stall warnings.

There should be lines containing "ver:" in your console output.  What
does one of the later one of these say?

							Thanx, Paul