rcuperf: Don't treat gp_exp mis-setting as a WARN

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0day found a boot warning triggered in rcu_perf_writer() on !SMP kernel:

	WARN_ON(rcu_gp_is_normal() && gp_exp);

, the root cause of which is trying to measure expedited grace
periods(by setting gp_exp to true by default) when all the grace periods
are normal(TINY RCU only has normal grace periods).

However, such a mis-setting would only result in failing to measure the
performance for a specific kind of grace periods, therefore using a
WARN_ON to check this is a little overkilling. We could handle this
inside rcuperf module via some error messages to tell users about the
mis-settings.

Therefore this patch removes the WARN_ON in rcu_perf_writer() and
handles those checkings in rcu_perf_init() with plain if() code.

Moreover, this patch changes the default value of gp_exp to 1) align
with rcutorture tests and 2) make the default setting work for all RCU
implementations by default.

Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Fixes: http://lkml.kernel.org/r/57411b10.mFvG0+AgcrMXGtcj%fengguang.wu@intel.com
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

...

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Boqun Feng 2016-05-25 09:25:33 +08:00 • committed by Paul E. McKenney

parent 5ef20f872d

commit af06d4f74a

1 changed files with 11 additions and 3 deletions

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kernel/rcu/rcuperf.c

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