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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-02-03 18:54:05 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-04-18 20:38:18 +0200 |
| commit | b8c78d3afc6aac1c722af3bec18959c6bd93231c (patch) | |
| tree | db484e9bace61147bdd18855c6e65511fb7802a3 /kernel | |
| parent | rcu: Place guard on rcu_all_qs() and rcu_note_context_switch() actions (diff) | |
| download | linux-b8c78d3afc6aac1c722af3bec18959c6bd93231c.tar.xz linux-b8c78d3afc6aac1c722af3bec18959c6bd93231c.zip | |
rcu: Default RCU_FANOUT_LEAF to 16 unless explicitly changed
If the RCU_EXPERT Kconfig option is not set (the default), then the
RCU_FANOUT_LEAF Kconfig option will not be defined, which will cause
the leaf-level rcu_node tree fanout to default to 32 on 32-bit systems
and 64 on 64-bit systems. This can result in excessive lock contention.
This commit therefore changes the computation of the leaf-level rcu_node
tree fanout so that the result will be 16 unless an explicit Kconfig or
kernel-boot setting says otherwise.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcu/tree.h | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index d2f276fc2edc..376c01e539c7 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -52,11 +52,7 @@ #ifdef CONFIG_RCU_FANOUT_LEAF #define RCU_FANOUT_LEAF CONFIG_RCU_FANOUT_LEAF #else /* #ifdef CONFIG_RCU_FANOUT_LEAF */ -# ifdef CONFIG_64BIT -# define RCU_FANOUT_LEAF 64 -# else -# define RCU_FANOUT_LEAF 32 -# endif +#define RCU_FANOUT_LEAF 16 #endif /* #else #ifdef CONFIG_RCU_FANOUT_LEAF */ #define RCU_FANOUT_1 (RCU_FANOUT_LEAF) |