srcu: Make Tree SRCU able to operate without snp_node array

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This commit makes Tree SRCU able to operate without an snp_node
array, that is, when the srcu_data structures' ->mynode pointers
are NULL.  This can result in high contention on the srcu_struct
structure's ->lock, but only when there are lots of call_srcu(),
synchronize_srcu(), and synchronize_srcu_expedited() calls.

Note that when there is no snp_node array, all SRCU callbacks use
CPU 0's callback queue.  This is optimal in the common case of low
update-side load because it removes the need to search each CPU
for the single callback that made the grace period happen.

Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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This commit is contained in:

Paul E. McKenney 2022-01-24 09:46:57 -08:00

parent 7b9e9b5856

commit 994f706872

2 changed files with 124 additions and 93 deletions

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14

include/linux/srcutree.h

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203

kernel/rcu/srcutree.c

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