rcu/nocb: Check for deferred nocb wakeups before nohz_full early exit

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In theory, a timer is used to defer wakeups of no-CBs grace-period
kthreads when the wakeup cannot be done safely directly from the
call_rcu().  In practice, the one-jiffy delay is not always consistent
with timely callback invocation under heavy call_rcu() loads.  Therefore,
there are a number of checks for a pending deferred wakeup, including
from the scheduling-clock interrupt.  Unfortunately, this check follows
the rcu_nohz_full_cpu() early exit, which renders it useless on such CPUs.

This commit therefore moves the check for the pending deferred no-CB
wakeup to precede the rcu_nohz_full_cpu() early exit.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

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Paul E. McKenney 2019-04-16 14:48:28 -07:00

parent c00045be32

commit 85f69b3212

1 changed files with 4 additions and 4 deletions

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kernel/rcu/tree.c

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