rcu/nocb: Remove rcu_node structure from nocb list when de-offloaded

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The nocb_gp_wait() function iterates over all CPUs in its group,
including even those CPUs that have been de-offloaded.  This is of
course suboptimal, especially if none of the CPUs within the group are
currently offloaded.  This will become even more of a problem once a
nocb kthread is created for all possible CPUs.

Therefore use a standard double linked list to link all the offloaded
rcu_data structures and safely add or delete these structure as we
offload or de-offload them, respectively.

Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

...

This commit is contained in:

Frederic Weisbecker 2021-11-23 01:37:03 +01:00 • committed by Paul E. McKenney

parent 0598a4d442

commit 2ebc45c44c

2 changed files with 43 additions and 9 deletions

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7

kernel/rcu/tree.h

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45

kernel/rcu/tree_nocb.h

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